Gunnar Hillert's Blog

DevNexus 2012 Early Bird Ends in 48 Hours!

2012-01-30T12:48:00.010-05:00

This is a friendly reminder that the Early Bird pricing for DevNexus 2012 ends in 48 hours on February 1 at 11:59pm. Therefore, please register for DevNexus at http://www.devnexus.com/ in order to secure your ticket for this wonderful conference at the low price of $185.

Date: March 21-22, 2012
Place: Cobb Galleria, Atlanta, GA
Cost: $185 (early bird price), $200 after February 1st.

DevNexus is the South-East's biggest conference for Java developers! We provide the best software professional development content at the lowest possible
price, bringing some of the world's best speakers & most interesting topics to Atlanta!

For 2012, we have an amazing line-up of speakers and sessions. Here is what you can expect:

2 days
6 tracks (2 more than last year!!)
48 sessions
3 keynote presentations
Food and beverages will be provided
Cocktail-hour with free sponsored drinks at the end of the first day
Raffles and give-aways (e.g. books)
Great networking opportunities
Ridiculously cost-effective value
DevNexus is organized by community volunteers (pro-bono) for the community!

Here is a list of topics that we will cover:

Core Java (Java 7+8, Joda-Time, Guava)
Mobile (PhoneGap, Android, Titanium Mobile)
HTML5
JavaScript (Node.js, jQuery)
Spring (Spring 3.1, Spring MVC 3.1, Spring Integration)
JBoss (Delta Spike, JBoss 7)
Cloud (Heroku, Cloud Foundry, Google App Engine)
Gradle
Groovy
Git
Scala
NoSQL (Neo4J, Cassandra)
Play Framework
EhCache
REST
Continuous deployment
Talks on Agile Methodologies and Architecture

The DevNexus website already contains 32 session abstracts which you can browse at:

http://www.devnexus.com/s/presentations

More presentation abstracts will be added shortly. We are also super-excited to offer 3 keynote presentations at DevNexus 2012. The opening keynote presenter will be Patrick Curran, Chair of the Java Community Process organization (JCP):

"Java User Groups and the Java Community Process: a winning combination"

Our second keynote presenter will be our very own Barry Hawkins, a veteran in our industry as speaker, developer, and agile coach and mentor.

"How We Got Here, And What To Do About It"

Please find more information about our keynote speakers, including keynote details, on our website at:

http://www.devnexus.com/s/speakers

This is THE conference you must not miss. Therefore, come join us for this incredible event.

Don't hesitate, sign up for DevNexus 2012 today at: http://www.devnexus.com

We would also like to thank our Sponsors that greatly help us to keep DevNexus so affordable:

Gold Sponsors:

Terracotta
IntercontinentalExchange (ICE)
JBoss
The Intersect Group

Silver Sponsors:

Apex Systems
Anteo Group

Lastly, please feel free to send this note to your present & past co-workers in the local software development community. Group discounts of 5 or more apply.

If you have any questions please contact us at:

info at ajug dot org
678-908-9067

See you all at DevNexus 2012!!!!

Sonar and Gradle Multi-Module Projects

2012-01-13T03:15:00.007-05:00

I love Sonar. It is a wonderful way to collect some metrics for your Java projects - hassle-free and wrapped in a sweet-looking UI. For Maven-based projects Sonar literally works out of the box. Just start up your Sonar instance (assuming you are using the default settings running on localhost) and then you simply fire it off using:

$ mvn sonar:sonar

A few moments later you should have the metrics available at:

http://localhost:9000/

Well, the past few days I was setting up a multi-module Gradle project for Sonar. Let me start by stating that Gradle is awesome. Having the ability to declare dependencies as one-liners and also being able to customize your scripts easily, yet having sensible defaults, is very nice. Kind of the best of both worlds.

Setting up Sonar for a multi module project, though, is unfortunately a bit more complicated, compared to what I am used to in the Maven world. It is not awfully complicated, but it took me a while to collect all the pieces of information.

Getting your Sonar plugin to just doing something is fairly simple. Just follow the basic steps outlined in the plugin documentation at:

http://gradle.org/docs/current/userguide/sonar_plugin.html

One differentiator between the Sonar Plugin for Gradle and Maven is, that the Gradle version does not automatically run code coverage analysis. This needs to be manually setup. This is where the official doc just vaguely refers to Cobertura.

First, I tried using Cobertura for code coverage, but I seemed to run into difficulties for my multi-module projects. The Cobertura Plugin is here:

https://github.com/valkolovos/gradle_cobertura/wiki

By chance I realized that the Sonar guys have a GitHub repository with samples on how to setup sonars for various build systems, including Gradle:

https://github.com/SonarSource/sonar-examples/

In their examples, they are using JaCoCo, which is not mentioned in the original Gradle docs and maybe I could have continued with Cobertura but it seemed that Sonar was preferring JaCoCo and thus I continued with that.

Some Gradle Sonar Plugin Limitations

The Gradle Sonar Plugin has an annoying limitation, where I can run it for the ROOT project OR for the sub-projects individually. See the following Gradle Jira ticket for details:

http://issues.gradle.org/browse/GRADLE-1813

Furthermore, I hit the minor issue that I cannot set the links in the Sonar dashboard. This seems to be related to the following Sonar Jira issue:

https://jira.codehaus.org/browse/SONAR-2749

The JaCoCo code coverage plugin is "slightly less" supported by the Gradle Sonar Plugin, e.g. the Gradle Plugin does not have an explicit setter for the JacocoReportPath and it assumes the "target" folder as the build directory by default. Therefore you must set explicitly:

props["sonar.jacoco.reportPath"]  = "${buildDirName}/jacoco.exec"

Lastly, I deviated a bit from the SonarSource Gradle example, and instead of System properties, I wanted to use Gradle properties to allow for users to provide non-default Sonar configuration settings (databasem url, jdbc parameters etc.). Well, while setting that up I ran into yet another Gradle Jira issue:

http://issues.gradle.org/browse/GRADLE-1826

But at the the end, I am happily able to run a multi-module Gradle project with Sonar and collecting Code Coverage statistics. Here is the relavant code from my build.gradle file:

apply plugin: 'sonar'

sonar {

    if (rootProject.hasProperty('sonarHostUrl')) {
        server.url = rootProject.sonarHostUrl
    }

    database {
        if (rootProject.hasProperty('sonarJdbcUrl')) {
            url = rootProject.sonarJdbcUrl
        }
        if (rootProject.hasProperty('sonarJdbcDriver')) {
            driverClassName = rootProject.sonarJdbcDriver
        }
        if (rootProject.hasProperty('sonarJdbcUsername')) {
            username = rootProject.sonarJdbcUsername
        }
        if (rootProject.hasProperty('sonarJdbcPassword')) {
            password = rootProject.sonarJdbcPassword
        }
    }

    project {
        dynamicAnalysis  = "reuseReports"
        withProjectProperties { props ->
            props["sonar.core.codeCoveragePlugin"] = "jacoco"
            props["sonar.jacoco.reportPath"]       = "${buildDirName}/jacoco.exec"
        }
    }

    println("Sonar parameters used: server.url='${server.url}'; database.url='${database.url}'; database.driverClassName='${database.driverClassName}'; database.username='${database.username}'")

}

subprojects { subproject ->

    ...

    // See http://www.gradle.org/docs/current/userguide/dependency_management.html#sub:configurations
    // and http://www.gradle.org/docs/current/dsl/org.gradle.api.artifacts.ConfigurationContainer.html
    configurations {
        jacoco //Configuration Group used by Sonar to provide Code Coverage using JaCoCo
    }

    // dependencies that are common across all java projects
    dependencies {
        ...
        jacoco group: "org.jacoco", name: "org.jacoco.agent", version: "0.5.3.201107060350", classifier: "runtime"
        ...
    }

    test {
        jvmArgs "-javaagent:${configurations.jacoco.asPath}=destfile=${buildDir}/jacoco.exec,includes=org.your.project.*"
    }
    ...
}

I hope this is useful information for all Gradle users out there.

Method Validation With Spring 3.1 and Hibernate Validator 4.2

2011-12-30T23:10:00.192-05:00

JSR 303 and Hibernate Validator have been some awesome additions to the Java ecosystem, giving you a standard way to validate your domain model across application layers. Combined with the annotations of the Java Persistence API (JPA) you have some very nice tools at your disposal to ensure that only valid data enters your database.

However, one piece of missing functionality was the ability to also validate method calls. For example, wouldn't it be nice if you could use normal JSR 303 annotations to safeguard business layer calls as well?

Of course you can enforce constraints programmatically, e.g. prevent the passing of Null parameters. Spring for instance provides the org.springframework.util.Assert class. However, it would be desirable, if constraints placed on input parameters as well as return values were part of the method contract.

Enter Hibernate Validator 4.2, which was released in June of 2011. It provides now method validation and Gunnar Morling, one of the committers, has an excellent write-up on this on his blog at:

http://musingsofaprogrammingaddict.blogspot.com/2011/01/method-validation-with-hibernate.html

Also, check out the Hibernate validator documentation regarding method validation. Gunnar Morling also provides some preliminary Spring support available at GitHub:

https://github.com/gunnarmorling/methodvalidation-integration

But the news for Spring aficionados is getting even better - Direct support for Method Validation With Hibernate Validator is now available in the lastest Spring 3.1 release that went GA just two weeks ago.

Specifically Spring 3.1 provides the following support in regards to method validation:

In order to get started, make sure that you are using Spring 3.1.0.RELEASE and that you have Hibernate Validator 4.2 in your classpath. That's all what you need to begin using JSR 303 annotations on the method level. For example, now you can annotate your methods using e.g.:

@Validated
public interface BusinessService {
    @NotNull String convertToUpperCase(@NotEmpty String input);
}

The @Validated Annotation indicates that the methods in the class are to be included for method validation. Keep in mind that you can specify your own annotation that will be enabling method level validation for the annotated class. Specify your own annotation by calling setValidatedAnnotationType on the MethodValidationPostProcessor.

However, placing the annotations themselves will not enforce the constraints 'automagically'. In fact Spring will be using AOP (Aspect Oriented Programming) Advices under the covers that delegate to Hibernate Validator. The easiest way to enable these advices is to declare a MethodValidationPostProcessor bean in your Spring application context as shown below.

 
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:context="http://www.springframework.org/schema/context"
 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
  http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

 <context:component-scan base-package="com.hillert.spring.validation" />

    <bean id="validator"
      class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean"/>
      
    <bean class="org.springframework.validation.beanvalidation.MethodValidationPostProcessor"/>
    
</beans>

For more details, I have published a small project over at GitHub that illustrates method level validation using Hibernate Validator:

https://github.com/ghillert/spring-hibernate-validator-sample

In order to get get started:

Clone the repository using $ git clone git://github.com/ghillert/spring-hibernate-validator-sample.git
$ cd spring-hibernate-validator-sample
Build the sample using Maven $ mvn clean package
Run it with$ mvn exec:java

The command-line based sample provides a simple String conversion service, that converts Strings to upper-case. You can insert those Strings from the command line. The Service layer will enforce the following constraints using method level Hibernate Validator annotations:

The input String must not be empty (not null and not an empty String)
The conversion service will never return null

In order to trigger validation exceptions you can enter some special strings:

Pressing just enter (no string entered) will cause an empty String parameter to be set
Submitting "null" (The String), will cause a null parameter to be set
When entering "returnnull", the underlying business method will return Null

The Main method will catch the occurring MethodConstraintViolationExceptions and print some details to the command prompt.

Lastly, the current method validator support via Spring is specifically targetting Hibernate Validator. However, there are standardization efforts underway as part of the Bean Validation 1.1 specification (JSR-349). In order to follow the progress, please follow also http://beanvalidation.org/.

Spring will provide support for JSR-349 as soon as the official standard has been ratified. In order to track inclusion into the Spring framework, please follow also Spring Framework Jira ticket SPR-8199 . As of today this feature should be available in the next Spring 3.2 release.

I hope this blog entry and the accompanying sample have showed you how easy it is to get started with method level validation using Spring and Hibernate Validator. Please let me know if you have further questions or run into issues.

Java Print Service Frustrations

2011-12-27T13:00:00.019-05:00

This is probably not the most exciting "toy" to play with for the holidays, but I wanted to explore some use-cases that involve printing through Java back-end services. Basically, in an enterprise environment you may run into requirements, where the documents you receive or generate also are required to be printed out for whatever reasons. In all honesty, I never had to deal with Java's print Apis and thus started from scratch.

It turns out, that there are 2 approaches (reminds me of the multitude of Date implementations...). One approach dates back to the 1990s and is called the Java 2 Print API and is tied more to User Interfaces (UI) triggering the printing process. With Java 1.4, the Java Print Service API (JPS) was introduced (JSR 6) which serves as a super-set of the the Java 2 Print Api.

The JPS Api is certainly workable but I ran into some serious trouble. For my initial use-case, I may receive simple text documents, e.g. XML that I want to send to a definable printer as plain text.

I was unable to get that to work on my Mac using Mac OS X 10.6.8. However, on my Windows JVM it worked flawlessly and my text files were printed out without any complaints. On my Mac, though, my little Java test application finishes without any errors but my printer queue states:

Error: pstopdffilter/pstocupsraster failed with err number -31000

Googling did not help much either. There seemed to be some anecdotal evidence that other people might have had trouble with text printing as well but I was unable to uncover definite answers (Many of the information is years old). The question I have is whether this is an issue with:

My Printer, which is a Brother HL-4070CDW
The Mac JVM (Mine is: build 1.6.0_29-b11-402-10M3527)
CUPS
something else

If any of the readers has encountered similar issues or is able to shed some more light into this issue, please let me know (THANKS!).

While searching for explanations, I stumbled across the following thread on stackoverflow.com: http://stackoverflow.com/questions/1655297/print-to-specific-printer-ipp-uri-in-java. There they mentioned the following CUPS specific libraries:

CUPS4J (http://www.cups4j.org/)
jipsi (http://sourceforge.net/projects/jipsi/)

Jipsi aparently changed names and moved to Google code:

JSPI (http://code.google.com/p/jspi)

As I need a generic solution that works not only on Mac using CUPS but also on Windows I have not experimented with any of the libraries above. Nevertheless I wanted to mention them.

I have also tried various other DocFlavors and settings but to no avail. What is interesting, though, is that the printing of PDF files works fine. Printing image files such as PNG or JPG fails as well.

Here is the trivial application that I am using:

import java.io.FileInputStream;
import java.io.FileNotFoundException;

import javax.print.Doc;
import javax.print.DocFlavor;
import javax.print.DocPrintJob;
import javax.print.PrintException;
import javax.print.PrintService;
import javax.print.PrintServiceLookup;
import javax.print.SimpleDoc;
import javax.print.attribute.HashPrintRequestAttributeSet;
import javax.print.attribute.PrintRequestAttributeSet;
import javax.print.attribute.standard.Copies;
import javax.print.attribute.standard.Sides;

public class PrintPS {

  public static void main(String args[]) throws FileNotFoundException, PrintException {
    FileInputStream textStream = new FileInputStream(args[0]); 
    DocFlavor myFormat = DocFlavor.INPUT_STREAM.AUTOSENSE;
    Doc myDoc = new SimpleDoc(textStream, myFormat, null); 
  
    PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet(); 
  
    aset.add(new Copies(1)); 
    aset.add(Sides.ONE_SIDED); 
  
    PrintService printService = PrintServiceLookup.lookupDefaultPrintService();
  
    System.out.println("Printing to default printer: " + printService.getName());
  
    DocPrintJob job = printService.createPrintJob(); 
    job.print(myDoc, aset); 

  }
}

Furthermore, I looked at the follwing Java-based Text editors to see how they accomplish printing (Which works fine on my Mac as well):

RTEXT (http://rtext.fifesoft.com)
jEdit (http://www.jedit.org)

RTEXT uses the DocFlavor: DocFlavor.SERVICE_FORMATTED.PRINTABLE which in turn uses a component that implements the java.awt.print.Printable Interface.

I guess, as a next step I have two options...go down into the trenches of Java2D or have some fun generating PDF files...And all I wanted was to print some simple text that works across Operating Systems.

DevNexus 2012 - Registration is Open

2011-12-07T20:43:00.001-05:00

The Atlanta Java Users Group is delighted to announce that registration for DevNexus 2012 is now open. In order to reserve your ticket, please go to:

http://www.devnexus.com/

DevNexus 2012 will be held on Wednesday, March 21st and Thursday, March 22nd at the Cobb Galleria Centre in Atlanta, GA. We already confirmed many amazing presenters covering a wide array of crucial technology topics.

In addition to providing great content for Java developers, DevNexus is a very valuable networking opportunity. This event attracts Java/JVM talent from diverse backgrounds, be it large corporations, consulting organizations or independent technology connoisseurs. You will have an opportunity to discover what other development teams are using as their favorite tools and practices.

Why should you attend DevNexus 2012:

Best Value: $185 Early Bird price (until Feb 1) for two full days of technology immersion and comaraderie.
Ask questions to world-class experts and fellow developers
Learn how to move your applications into the cloud (covering Cloud Foundry, Heroku, Google App Engine, OpenShift)
Learn Agile Best Practices & Tools
Learn more about core Java topics as well as other languages on the JVM
Learn more about building rich (mobile) web-application applications, e.g. using HTML5
Hear about the latest developments from JBoss and SpringSource

We have already lined-up some impressive speakers, with many more to be announced in the upcoming weeks:

Tim Berglund - Covering NoSQL topics
Patrick Curran - Chairman of the JCP, keynote speaker
Hans Dockter - Founder of Gradle
Ben Evans - Covering various core Java topics including Java 8
Mark Fisher - Spring Integration Lead, covering Enterprise Integration Patterns (EIP) and Cloud Foundry
Barry Hawkins - Covering Agile Methodologies
Josh Long - Spring Developer Advocate
Pratik Patel - Mobile/Web, Java
Rossen Stoyanchev - Spring MVC Lead
James Ward - Covering Heroku and Play framework

Fore more details on speakers please visit:

http://www.devnexus.com/s/speakers

We also would like to thank our sponsors for their support in making DevNexus a success:

Gold Sponsors

Silver Sponsor

Anteo Group

We hope to see you all at DevNexus, and please register for this incredibly valuable event at:

http://www.devnexus.com/

Cloud Foundry for Spring Developers - Slides

2011-12-01T01:21:00.000-05:00

Yesterday, I presented "Cloud Foundry for Spring Developers", at the Atlanta Spring User Group. I finally got around to upload the presentation slides to Slideshare:

http://www.slideshare.net/hillert/cloud-foundry-for-spring-developers

I would like to thank everyone for coming to the presentation! Cloud Foundry rocks!

Cloud Foundry for Spring Developers

2011-11-29T11:00:00.000-05:00

I will be presenting at the Atlanta Spring User Group tonight (Nov 29, 2011) at 6:30pm. For more details, including directions, please visit:

http://www.meetup.com/AtlantaSpring/

Title: Cloud Foundry for Spring Developers

Session abstract:

This session provides an overview of how to build and deploy Spring-based applications to the Cloud Foundry platform.
The session will cover application configuration parameters, binding services to your application, deployment options using using STS, the vmc command tool, as well as the new Apache Maven plugin for Cloud Foundry. Gunnar will demonstrate how to deploy applications to both micro and public Cloud Foundry and will also show how debugging works with Cloud Foundry and how you can inspect services remotely using Caldecott.

Gunnar will also show various options to keep your War-files deployable to both Cloud Foundry and stand-alone Servlet Containers using Auto-Reconfiguration, the Cloud namespace, and Spring 3.1 profiles.

Lastly, he will give a high-level overview how you can use Cloud Foundry together with Spring Integration in order to create scalable Spring applications.

DevNexus 2012 - Call For Papers Now Open

2011-11-02T09:40:00.000-04:00

The DevNexus™ 2012 developer conference is taking place March 21-22. We are delighted to announce the Call for Papers is now open. We are looking forward to receiving your amazing proposals covering one of the following topics:

Java and JVM Languages
Cloud
NoSQL
Web (incl. Mobile Development, HTML5, JavaScript)
Methodologies and Tools

We do not encourage overt marketing pitches. Sessions are 75 minutes long and we encourage breakout sessions, work-shops and case studies. Please include the following information:

Name
Job Title
Email
Twiter id
Company
Presentation Title
Audience Level (General, Beginner, Intermediate, Advanced)
Presentation Abstract
Your Bio

Please submit your proposals as soon as possible to info at ajug.org. The Call for Papers closes January 15, 2012.

The planning committee will carefully review your proposals, and you will get a confirmation whether your talks are selected or not for the DevNexus™ conference.

For more information, please visit: http://www.devnexus.com/

Maven and Cloud Foundry - The plugin is here!

2011-09-22T16:54:00.003-04:00

It has been an amazing time so far for me working at SpringSource for the past couple of months and today I have finally published my first blog post for the official SpringSource blog. The blog post also marks the Milestone 1 (M1) release of the Cloud Foundry Maven Plugin which will make it much easier for Maven users to deploy their applications to Cloud Foundry.

Thus, checkout the blog post, use the plugin and follow the project over at GitHub. Please provide plenty of feedback - it is highly appreciated!

OSCON 2011 - Mission Accomplished

2011-07-29T02:35:00.000-04:00

OSCON 2011 - Mission Accomplished and a week of amazing learning and networking is finally coming to an end. I had flown in not only for OSCON Java but also for the Community Leadership Summit, that took place last Saturday and Sunday (but Sunday, I attended the JVM languages day instead, which was wonderful as well).

I was super-impressed with the variety of people from all over the planet, not only the US but also Europe and the Americas. E.g. if you saw somebody wrapped in a flag…that was Bruno Souza, the man that has put Brazil on the map for Java developers. Furthermore, all the cool open-source companies that you could ever think of were present as well. Just an awesome level of energy there.

Also, I was able to connect with a ton of VMware/SpringSource folks at the event that I hadn’t met personally before, yet. Just to give you an idea of how awesome the open-source community is: On Tuesday we went out for some great food at McMenamins Kennedy School. It is housed in an old school with everything left intact/restored (incl. the showers in the rest rooms). That place has 5 bars, restaurant and excellent outdoor seating.

Anyway, our group included Dan Allen from JBoss (member of the Seam, Weld and Arquillian projects), Peter Neubauer from Neo4J (Founder, good chance for me to speak some German ;-), William Rowe from SpringSource (Apache Foundation Vice President, HTTP Server), David Blevins from IBM (Co-founder of Geronimo and OpenEJB), Mark Johnson from SpringSource (President of NEJUG), Bruce Snyder from SpringSource (ActiveMQ comitter), Josh Long from SpringSource (Developer advocate and author), Steve Mayzak from SpringSource (Author). Seriously, to me, this was like being backstage! Thanks for having the chance to meet you all!

Back to OSCON here are the sessions I was able to attend:

Monday

Theory of Caching (Greg Luck)
Java Puzzlers – Scraping the Bottom of the Barrel (Josh Bloch, Bob Lee)
The Ghost in the VM: A Reference to References (Bob Lee)

Tuesday

Everything You Wanted to Know about Open Source that Nobody Told You (Jeff Genender)
Managing Thousands of Cloud Instances with Java (Patrick Lightbody)
ActiveMQ in Action – Common Problems and Solutions (Bruce Snyder)
The Evolution of Java: Past, Present, and Future (Josh Bloch)
From Ruby on Rails to Java: The Gory Details (Steve Jenson)
A Giant Hop Forward with Spring Roo (Steve Mayzak and Josh Long

Priority Channels in Spring Integration

2011-07-21T23:15:00.000-04:00

As somebody was asking about a Priority Channel example for Spring Integration in the forums today, I went ahead and created a simple example. You can grab the source code over at GitHub:

https://github.com/ghillert/spring-integration-examples/tree/master/priority-channel-example

For some additional information check out the related forum entry:

http://forum.springsource.org/showthread.php?112368-PriorityQueue-example-needed

HTML5 WebSockets for JVM Developers

2011-07-04T10:45:00.004-04:00

Anything related around HTML5 seems to be a hot button topic these days and lucky for me that I got an opportunity to take a deep dive into WebSockets. Thus, I will use this blog to post my findings over the next few days and I will present some simple code examples as well.

Anyway, WebSockets allow Servers to basically "push" data back to subscribed Browser clients in an effective manner instead of using workarounds such as long-polling. The WebSockets API is being standardized by the W3C (http://dev.w3.org/html5/websockets/) and the actual protocol is being defined by the Hypertext-Bidirectional (HyBi) working group (Part of IETF) - http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-09.

For further reading and to learn more about WebSockets in general, please also check out the following resources:

It turns out, though, that the only browsers, that support WebSockets out of the box right now, are Safari and Chrome. Wait - Firefox is not supported? Well, Firefox does support WebSockets but it is disabled by default due to security issues with the implemented draft version of the WebSocket protocol (Firefox 4+5). You can find more information about this here:

Nonetheless, if you're interested, you can re-activate WebSockets in Firefox 4 and 5 quite easily. Take a look at the following link for more information on how to do this:

http://techdows.com/2010/12/turn-on-websockets-in-firefox-4.html

Firefox 6 is supposed to bring back websockets support, albeit using a newer draft of the websocket protocol (hybi-07), which is not backwards compatible.

What about Web Servers?

Okay, so WebSockets look cool, yet with limited browser support. Furthermore, different webservers have varying stages of support for asynchronous messaging, with Jetty and Glassfish being the best options currently a provide native websocket support. It looks like Resin also has direct websocket support. See also:

http://java.dzone.com/articles/creating-websocket-chat

Tomcat 7 currently does not support WebSockets, yet. Check out the following issue tracker entry to learn more about the current state of affairs in Tomcat 7:

https://issues.apache.org/bugzilla/show_bug.cgi?id=51181

What's next?

So, essentially what we want is some kind of framework that supports "graceful degradation": when available a suitable framework shall use websockets, but if not available, the framework should fall back to more traditional push work-arounds such as long-polling.

On the server-side, I am running Java, and therefore, I need a respective implementation on that platform. Choices, though, seem to be rather limited and I came up with the following list of options:

Atmosphere (http://atmosphere.java.net/)
Socket.IO (http://socket.io/) - Orginally for Node.JS there are Java implementations available
jWebSocket (http://jwebsocket.org/)
Stomp Websocket for HornetQ and ActiveMQ (http://jmesnil.net/stomp-websocket/doc/)

Just for reference, there seems to be quite some activity going on outside of Java:

My choice for now

Socket.IO looks like it has quite some traction but the default implementation is for Node.JS. There are Java implementations available but they did not seem to have much traction. jWebSocket actually looks promising but its licensing (LGPL) is too restrictive to me (My choice needs to be Apache license compatible ;-).

Out of the list above, I chose Atmosphere (http://atmosphere.java.net/). Atmosphere has pretty much all the features you would like to have incl. detecting server-side capabilities and using the best possible approach transparently. Atmosphere comes with a jQuery plugin that abstracts away the implementation details (same Api for using long-polling vs. websockets)

While Atmosphere comes with quite a few examples, they are interestingly mostly for JAX-RS and there are no examples for Spring MVC. Also, the documentations is rather limited but luckily you get very swift and helpful responses from Atmosphere mailing list.

In my next posting, I will provide a little example integrating Spring MVC and Atmosphere. So stay tuned.

Nevertheless, if you have other WebSocket recommendations and/or thoughts, please leave comments!

PS:

A funny thing, I just realized that Burr Sutter, a friend of mine and fellow AJUG board member wrote down his WebSockets research experiences as well. It is a small world. Go check it out at:

http://burrsutter.blogspot.com/2011/02/html5-websockets-adventure.html

Testing Email Notifications with Apache James 3.0

2011-05-24T01:30:00.004-04:00

On windows machines I have been using Mailster for testing email notifications. Unfortunately, I had issues with Mailster in the past running on non-Windows machines. Thus, on Mac I have been using a local Postfix instance, which forwarded email to dedicated (real) mailboxes. But, it involved a bit of customization and ultimately I had to "know" to which mailboxes I wanted to send notifications to.

However, ideally I don't really care about email addresses. Instead I typically want to verify that the format and layout of the generated emails are good, be it text emails ort Html emails. Ultimately, it would be nice, if for testing, all notification sent ended up in ONE mailbox for development testing purposes.

Enter Apache James. Not long ago I came across this wonderful blog posting below about using Apache James 2.x in order to test application email notifications:

http://livingtao.blogspot.com/2007/05/testing-application-generated-emails.html

IT is amazing to see that this is pretty much the only dedicated blog posting on the internet regarding a seemingly very common issue. You would think that almost every serious enterprise application has to sent out email notifications, and be it solely for the "forgot password" feature. What is so fantastic about using Apache James, is that it allows you to test Email notifications, while sitting on a plane with no internet in sight. Just run everything locally.

Anyway, the steps illustrated in the blog above also work nicely for James 3.0 (currently milestone 2). What is pretty cool about Apache James is that it is now Spring-based :-)

Here are the simple steps to get things set up for Apache James 3.0:

Download Apache James 3.0
Unzip the downloaded archive
Edit mailetcontainer.xml in directory /conf/
Search for "<processor name="transport">"
Replace the entire element that starts with "<mailet match="All" class="RemoteDelivery">" with: "<mailet match="All" class="Forward"> <forwardto>test@localhost</forwardto></mailet>"
Startup Apache James 3.0 using sudo /bin/run.sh (Sudo is needed for local permissions)
Connect via Telnet to Apache James using: telnet localhost 4555 (User: root password: root)
Type: adduser test test <return>
Setup Thunderbird (or your favority email application)

I hope this gives you enough starting points for setting up email notification testing. Please leave comments if you see areas I can improve upon. Onward...

Spring 3.1 Bean Definition Profiles - Use Case

2011-04-30T11:10:00.002-04:00

As I am diving deeper into VMware's Cloud Foundry, I decided to make the DevNexus conference web-application fit for Cloud Foundry. However, instead of creating an explicit version of the application for Cloud Foundry, my goal is to have one War file that can be deployed without modifications to either CloudFoundry or a stand-alone servlet container.

Here one new Spring 3.1 feature comes in handy: Bean definition profiles. Bean definition profiles allow you to conditionally load Spring beans. There are some great resources already out there on how to use Bean definition profile, and thus I won't go into the details here:

How am I using Bean Definition Profiles for the DevNexus web-application?

Personally, I like to develop web applications that can run in a wide variety of environments with as little configuration as necessary. For my use-case, I want to create a single war file that can be deployed to the cloud, but which can also be deployed into your locally running Tomcat, Jetty, etc.

Furthermore, I believe that bean definition profiles can also be very useful for demo/integration testing purposes. For web applications, I like the concept of "application home directories". They contain configuration files (e.g. DB connectivity parameters), data files such as for Hibernate Search etc.) and the web application will reference the home directory either through a system property, environment variable or looks in a default directory in your user directory. But what if the home directory does not exist?

If the home directory does not exist, then the application runs in demo mode (or embedded mode), which means, the application use an embedded database for persistence and to also loads a set of seed+demo data at application startup-up.

Summarizing, I can think of the following Web application "modes" aka profiles:

Embedded mode (Integration testing and Demo mode)
Cloud Foundry mode (e.g. reference the MySql service, don't use file-system properties)
Stand-alone deployment mode (Uses home directory)

Thus, I can create a dedicated Bean definition profile in my Spring application context for each mode. Here is an example I have:

 <beans profile="default">
        <bean id="propertyConfigurer"
            class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
            <property name="searchSystemEnvironment" value="true" />
            <property name="locations">
                <list>
                    <value>file:${TING_HOME}/ting.properties</value>
                </list>
            </property>
        </bean>
        <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
            destroy-method="close">
            <property name="driverClassName" value="${database.jdbc.driverClassName}" />
            <property name="url" value="${database.jdbc.url}" />
            <property name="username" value="${database.jdbc.username}" />
            <property name="password" value="${database.jdbc.password}" />
            <property name="maxActive" value="100" />
            <property name="maxIdle" value="30" />
            <property name="maxWait" value="1000" />
            <property name="poolPreparedStatements" value="true" />
            <property name="defaultAutoCommit" value="true" />
        </bean>
        <bean id="entityManagerFactory"
            class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
            <property name="dataSource" ref="dataSource" />
            <property name="jpaVendorAdapter" ref="hibernateJpaVendorAdapter" />
            <property name="persistenceUnitName" value="base" />
            <property name="jpaProperties">
                <props>
                    <prop key="hibernate.dialect">${database.hibernate.dialect}</prop>
                    <prop key="hibernate.query.substitutions">true '1', false '0'</prop>
                    <prop key="hibernate.generate_statistics">true</prop>
                    <prop key="hibernate.cache.use_second_level_cache">true</prop>
                    <prop key="hibernate.cache.use_query_cache">true</prop>
                    <prop key="hibernate.cache.region.factory_class">net.sf.ehcache.hibernate.EhCacheRegionFactory</prop>
                    <prop key="hibernate.show_sql">${database.hibernate.show_sql}</prop>
                    <prop key="hibernate.format_sql">true</prop>
                </props>
            </property>
        </bean>
    </beans>
    <beans profile="cloud">
        <cloud:data-source id="devnexus-db"/>
        <bean id="entityManagerFactory"
            class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
            <property name="dataSource" ref="devnexus-db" />
            <property name="jpaVendorAdapter" ref="hibernateJpaVendorAdapter" />
            <property name="persistenceUnitName" value="base" />
            <property name="jpaProperties">
                <props>
                    <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
                    <prop key="hibernate.query.substitutions">true '1', false '0'</prop>
                    <prop key="hibernate.generate_statistics">true</prop>
                    <prop key="hibernate.cache.use_second_level_cache">true</prop>
                    <prop key="hibernate.cache.use_query_cache">true</prop>
                    <prop key="hibernate.cache.region.factory_class">net.sf.ehcache.hibernate.EhCacheRegionFactory</prop>
                    <prop key="hibernate.show_sql">false</prop>
                    <prop key="hibernate.format_sql">true</prop>
                    <prop key="hibernate.hbm2ddl.auto">create-drop</prop>
                </props>
            </property>
        </bean>
    </beans>
    <beans profile="embedded">
        <jdbc:embedded-database type="H2" id="dataSource"/>
        <bean id="entityManagerFactory"
            class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
            <property name="dataSource" ref="dataSource" />
            <property name="jpaVendorAdapter" ref="hibernateJpaVendorAdapter" />
            <property name="persistenceUnitName" value="base" />
            <property name="jpaProperties">
                <props>
                    <prop key="hibernate.dialect">org.hibernate.dialect.HSQLDialect</prop>
                    <prop key="hibernate.query.substitutions">true '1', false '0'</prop>
                    <prop key="hibernate.generate_statistics">true</prop>
                    <prop key="hibernate.cache.use_second_level_cache">true</prop>
                    <prop key="hibernate.cache.use_query_cache">true</prop>
                    <prop key="hibernate.cache.region.factory_class">net.sf.ehcache.hibernate.EhCacheRegionFactory</prop>
                    <prop key="hibernate.show_sql">false</prop>
                    <prop key="hibernate.format_sql">false</prop>
                </props>
            </property>
        </bean>
    </beans>

What about integration testing?

As of writing this blog posting the latest Spring 3.1 release is: 3.1.0.M1 and there is no explicit support for selecting profiles in your test declaratively. There is, though, the following new feature request Jira:

https://jira.springsource.org/browse/SPR-7960 - "TestContext framework should support declarative configuration of bean definition profiles"

This feature is scheduled for Spring 3.1 M2, but in the meantime, I use a static block which does the trick:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(
        locations={
          "classpath:spring/applicationContext-core-data.xml",
          "classpath:spring/mainApplicationContext.xml"
                 })
public abstract class BaseDaoIntegrationTest {
 
static {
  System.setProperty("spring.profiles.active", "embedded");
 }
 
    protected @PersistenceContext(unitName="base") EntityManager entityManager;

}

Over the next few days I hope to deploy an updated DevNexus application to Cloud Foundry, so stay tuned for updates.

First explorations into SpringSource's CloudFoundry

2011-04-14T14:40:00.006-04:00

I received my credentials last night for SpringSource's CloudFoundry and I am now in the process of going through the examples. Next, I plan to make some of my applications (home-projects) work on the cloud. The general documentation so far seems to be a still a bit scattered. Therefore, below I summarize all the documentation and resources I have used so far to immerse myself into the services provided by the CloudFoundry. Hopefully it provides a good starting point for you as well.

Background information

There are quite a few examples posted on GitHub, that are a tremendous help in getting started:

https://github.com/SpringSource/cloudfoundry-samples/

Deploy Applications to the cloud from within Eclipse (STS)

http://blog.springsource.com/2011/04/13/using-cloud-foundry-from-sts/

Deploy Applications to the cloud using the command line tool vmc

http://cloudfoundry.zendesk.com/entries/20012337-getting-started-guide-command-line-vmc-users

Spring Roo Support

http://www.springsource.org/roo/guide?w=base-cloud-foundry

Groovy/Grails

http://blog.springsource.com/2011/04/12/one-step-deployment-with-grails-and-cloud-foundry/

Further reading
Mark Fisher published a great general article covering both, the vmc command line tool and Eclipse:

http://blog.springsource.com/2011/04/12/cloud-foundry-for-spring-developers/

Make also sure you hit the forums:

http://cloudfoundry.zendesk.com/forums

And when you really want to look under the hood, take a look at the source code for CloudFoundry at:

http://cloudfoundry.org/

It seems like that when checking out CloudFoundry, it is also a great opportunity to familiarize yourself with Spring 3.1 (see this Spring blog post detailing some of the new features). While I think it is not strictly required it provides functionality that is quite useful for cloud deployment scenarios such as:

Bean definition profiles (Useful to cover both, local and cloud deployment)
Spring's new Environment abstraction

More details on that in my next blog post. Back to the cloud...

Spring Integration - Camellos Continued

2011-04-04T01:08:00.003-04:00

We had a great DevNexus conference this year and we were extremely blessed, that the project leads of both, Apache Camel (Claus Ibsen) and Spring Integration (Mark Fisher), spoke at the conference. In my opinion both frameworks are probably the best integration frameworks on the JVM!

Back in late 2009 I had written a blog post, where I presented some results from my Apache Camel learning experience. Now in 2011 it is time to do the same for Spring Integration. I am in the process of creating a few examples for Spring Integration that I create while learning it. So my hope is to create a little series of blog posts covering Spring Integration and Enterprise Integration Patterns (EIP) in general.

Nevertheless, don't forget to check out the wonderful examples that are provided via the Spring Integration Git repo at: http://git.springsource.org/spring-integration/samples/. It contains a sophisticated list of examples and is the best place to get started.

Well, let's get started - The source code for my example is available via GitHub, and will be successively expanded with additional examples in the coming weeks:

https://github.com/ghillert/camellos-spring-integratio
git://github.com/ghillert/camellos-spring-integration.git

For right now the implemented core Spring Integration functionality in Camellos si is the following:

A user drops a file in a local directory (/camellos-si/data/inbox/), that is continuously polled by Spring Integration.
The file is picked up by Spring Integration and converted to a byte array with the original file being deleted.
The resulting byte array is sent to an in-memory channel.
A custom transformer will pick up the data array and compress the data using a ZipOutputStream
The resulting byte array is yet again being sent to another channel.
Finally an Outbound Channel Adapter will grab the data from the channel and send it via Ftp to an embedded Ftp server (stored under: /camellos-si/data/ftp/).

In order to try it out - just download camellos-si-distribution-1.0.zip from the downloads section at https://github.com/ghillert/camellos-spring-integration. Unzip it and start the application by executing:

java -jar camellos-si.jar

That's it. Spring Integration should boot up and you can drop files you want to zip up into '/camellos-si/data/inbox/'.

* * *

Some interesting additional features covered by my example:

Maven Shade Plugin (http://maven.apache.org/plugins/maven-shade-plugin/)

The Maven Shade Plugin can be a nice simplifier in stand-alone deployment scenarios. Let's say you have a project with multiple jar dependencies, then you can use this plugin to merge all jar dependencies into one single jar. You can also configure the Maven Shade Plugin so that it generates the Main-Class property in META-INF/MANIFEST.MF and consequently, you can deliver a single jar (No class-path hell) and execute the application like my simple example:

java -jar camellos-si.jar

Maven Assembly Plugin (http://maven.apache.org/plugins/maven-assembly-plugin/)

The Maven Assembly plugin helps with creating distributable packages. For instance for my example I need not only the compiled jar file but I also need a few directories in the right place, e.g. Apache FtpServer requires the users.properties file to be an actual file (having it as a class path resource embedded in your jar won't work).

Basically, you can use the Maven Assembly Plugin to move things around and to mold your resulting distributable package (a Zip file in my case).

Embedded Ftp Server using Apache FtpServer (http://mina.apache.org/ftpserver/)

Something I always find intriguing with Spring is the simple embedability of additional services such as running ActiveMQ embedded in your Spring context by just adding a single line of Xml, or in this case embedding Apache FtpServer. I know it is a blurry line where you start building your own application server but mentally I still find it easier to do it in Spring than using an app server, particularly when you only want to do it for testing, showcasing etc. and move on to use external ActiveMQ, Ftp Server instances for production etc.

I hope this example has been enlightening for your own Spring Integration discoveries - stay tuned for more.

DevNexus 2011 - Tools to Get Stuff Delivered

2011-03-08T07:56:00.001-05:00

Dear fellow developers,

DevNexus 2011 is only 2 weeks away (March 21-22) and if you haven't registered, yet, please seize the moment and register athttp://www.devnexus.com/. Please hurry as registration is closing in one week.
Already, we are pleased to note that we surpassed the number of attendees compared to last year's conference. A big THANK YOU to all of you that registered so far!!

We will be having several raffles:an iPod Nano provided by JBoss, a Flash Builder 4 Premium license provided by Adobe and we will raffle a selection of books. Zero Turnaround is giving to every attendee a JRebel + Enterprise Add-on licenses (for 4 months).

And that is not all! We will have a cocktail hour on March 21st, which is an awesome opportunity to network, talk to speakers and enjoy free drinks.

DevNexus 2011 is your chance to learn about the latest trends in mobile application development, UI frameworks, NoSQL, core Java technologies and the latest from JBoss, Springsource and much more.

This year we also have a focus on Tools and Best Practices that make you more productive as a developer which encompasses an exciting set of sessions such as:

Git Foundations and Advanced Git Tricks
http://www.devnexus.com/s/presentations#1119
http://www.devnexus.com/s/presentations#1120

Gradle
http://www.devnexus.com/s/presentations#1115

Arquillian
http://www.devnexus.com/s/presentations#1152

Selenium RC
http://www.devnexus.com/s/presentations#1158

There are many more sessions to choose from - a total of 35 sessions (incl. 3 keynotes) across 4 parallel tracks. Our schedule is now finalized - Take a look at: http://www.devnexus.com/s/schedule

We would also like to thank our sponsors, who help us tremendously by off-setting much of the substantial costs associated with this event:

Gold Sponsors

Terracotta
The Intersect Group
Automated Logic Corporation

Silver Sponsors

Blackberry
Anteo Group
4t Networks
ICE
JBoss

Cocktail Hour Sponsor

MATRIX

Please join us for this amazing event and register at: http://www.devnexus.com/

Thank you all and we will be delighted to see you in 2 weeks!

Cheers,

Gunnar

Advanced Java, JRuby, Spring, Google, JBoss and DevNexus 2011

2011-03-03T01:24:00.001-05:00

DevNexus 2011 - March 21st & 22nd (www.devnexus.com) - Registration will be closing soon.

Several large teams have already registered and this is the best event to have your team attend - the injection of new technologies, techniques and ideas from some of the world's best technologists as well has having other professional software developers to mingle with. We will soon hit max capacity for the event so please complete your registrations today.

The DevNexus organizing committee looks for the best speakers and hottest topics in the software development industry and this year we have had a tremendous response from notable presenters. The following are just a few of the DevNexus speakers:

Jevgeni Kabanov - the founder and CTO of ZeroTurnaround (JRebel) will be addressing JVM memory management and classloading - these are excellent sessions for your most hardcore Java coders
Dick Wall - of the JavaPosse will dive into functional languages and overall best practices for software practitioners
Bob McWhirter - the prolific founder of open source solutions such as Codehaus.org, Drools and Groovy will address Ruby/JRuby on his new project TorqueBox - the power of Ruby raised to the power of JBoss
Claus Ibsen - the project lead for Camel and co-auther of the "Camel in Action" book will focus on enterprise integration
Mark Fisher - the project lead for Spring Integration will address AMQP and the "Cloudy Future of Integration"
Hans Dockter - the founder and project lead for Gradle will focus on automated build systems

And many more notable speakers discussing great topics...http://www.devnexus.com/s/speakers

Hadoop
Git
Scala
Arquillian
Flex
jQuery
Sproutcore
Selenium
Gradle
Apache Camel
Spring Integration, Mobile, Social
JBoss
TorqueBox
Apache Shiro
GWT
Google App Engine
NoSQL
The Future of Java
...

If you wish to subscribe to future Atlanta Java Users Group Announcements, please visit
http://www.ajug.org/confluence/display/AJUG/MailingLists

We look forward to seeing you at future AJUG Events and DevNexus 2011.

Sincerely,
Burr
770-714-3292

DevNexus 2011 - Craft Rich (Mobile) Internet Applications

2011-02-22T13:41:00.000-05:00

Dear fellow developers,

DevNexus 2011, the south-east's premiere developer conference is only a few weeks away and will take place March 21-22 in Atlanta, GA - Come join us and learn the techniques and technologies that will boost your corporate projects and personal skills to the next stage of excellence.

We are currently living in an age of massive changes that are transforming our industry. No longer is it acceptable to release static web applications as we did back in the Struts 1.x days. Our customers demand more - rich, interactive and responsive applications that also need to be available across multiple devices - not only desktops but also smart phones and tablets. It is becoming the new reality - Prepare yourself!

DevNexus will help you discover the possibilities and techniques to master this exciting world of Rich Internet Applications (RIA). And thus, we dedicated an entire track to cover:

GWT - David Chandler from Google will show you the latest developments around GWT 2.1
PhoneGap - Josh Marinacci from HP/Palm will show you how to develop mobile web applications using GWT and PhoneGap
jQuery - Learn from Pratik Patel how you can use jQuery 1.5 to built great UIs and how it helps you to loose the fear of JavaScript. Also learn how jQuery Mobile can help you createHTML5 based cross-device compatible mobile web applications. (The mobile web version of DevNexus.com is powered by jQuery Mobile - http://www.devnexus.com/s/index?site_preference=mobile)
SproutCore - Did you know that both Apple's MobileMe and iWork.com are powered by SproutCore? Yehuda Katz will show you the possibilities that this exciting JavaScript framework offers.
Flex - James Ward covers the new features in the upcoming Flex 4.5 release that will allow you to develop mobile applications across multiple devices (Android, RIM's Playbook, iPhone)
Spring Mobile - Need to serve mobile and desktop content from the same domain and or even the same Urls? Come and listen to Roy Clarkson's and Keith Donald's presentation on Spring Mobile
Spring Social - SpringSource co-founder Keith Donald will show you how to add "social features" to your applications using a common Api to integrate Twitter, Facebook and LinkedIn

Furthermore, we will have a keynote by Yehuda Katz, member of the jQuery and Ruby on Rails core team. Yehuda will show us how to build web applications in a multi-device world covering among other things HTML5.

This is an incredible line-up of sessions covering (mobile) web application development. What is even better - This is just one track. There are 3 more tracks covering core Java topics, NoSQL and many more crucial topics.

Take a look at our schedule at: http://www.devnexus.com/s/schedule

This is AJUG's biggest DevNexus event ever!

Don't hesitate, take the plunge and please register at http://www.devnexus.com/

Spring Mobile M3 - Site Preference

2011-02-07T00:30:00.080-05:00

A few weeks ago I started playing with Spring Mobile. For my app I want to use existing Spring MVC controllers to render different views depending on whether the client is a mobile device or a classic browser.

For that purpose Spring Mobile is really a very helpful asset (See my last Spring Mobile related blog post for more details).Back then I investigated a feature that allows you to manage a user's site preference. For example, the normal use case is that a user with a mobile device only sees the mobile version of your website.

Wouldn't it be desirable, though, to allow the user to switch to the full version of the website as well? While hopefully not a regular use-case, your site's visitor may be for instance interested in some additional content that is unavailable in the mobile version. A good example for me is Wikipedia. For normal use, the mobile web version of Wikipedia is certainly quite functional. However, I am also bi-lingual (plus aspiring to learn Spanish), so I often use Wikipedia to look up articles, let's say in German, but then I want to switch over to the Spanish version of the same article in order to find certain translations. Because I can't do the language switch in the mobile web version, I at least have the option to change back to the full Wikipedia version and switch the article's language there.

Well, Spring Mobile has a feature for site preference but unfortunately that feature (when I checked in the M2 release) had some limitations. It only worked with the SiteSwitcherHandlerInterceptor. This interceptor assumes you want to redirect the user to a dedicated mobile sub-domain that is hosting your application's mobile version.

In my simple use-case, however, I want to keep the mobile and non-mobile content on one domain (same urls) but let mobile users change to the full version of the website and stay on that full version for the duration of their session (or set via cookie for the duration of multiple visits).

Unfortunately, the "site preference" feature back then was somewhat embedded in the M2 release and you could not use it stand-alone easily. Well, I headed over to the Spring forums and posted my issue there and within 3 days, Keith had implemented and commited improvements for my requirements (I was truly impressed with the feedback!)

Well, only a month later, I finally found the time to look at the latest changes regarding the site preference feature. This has coincided also with the Spring Mobile M3 release 1 day later, which contains all the latest features.

Checking out and building Spring Mobile

But in case you want to anyway, you can check out and build the Spring Mobile project easily yourself using Git and Gradle. You will find the sources here: http://git.springsource.org/spring-mobile

Just FYI, I was unable to check out the Spring Mobile project using Eclipse's EGit. It looks like Egit does not support (??) Git submodules, a feature used by Spring Mobile. However, checking out the project from the command line using worked well:

git clone --recursive git://git.springsource.org/spring-mobile/spring-mobile.git

Building project using Gradle is trivial. Under the spring-mobile directory execute either ./gradlew build or gradlew.bat. You don''t even have to have Gradle installed locally - it downloads Gradle for you. I am Maven fan but that was impressive!! I really owe it to myself to look at Gradle more closely very soon.

Spring Mobile M3 Changes regarding Site Preference

Anyway, the changes regarding the site preference feature in the M3 release are satisfying my needs perfectly. The site-preference functionality has been refactored out into its own feature and Spring Mobile now provides the following separate features:

Device Resolution
Site Preference Management
Site Switching

The documentation has also been updated and is reflecting the feature changes and is quite helpful in that regard. Here is the configuration necessary to configure site-preference for my use-case:

I updated my Maven dependencies to:

     <dependency>
         <groupId>org.springframework.mobile</groupId>
         <artifactId>spring-mobile-device</artifactId>
         <version>1.0.0.M3</version>
     </dependency>

I updated my spring web context xml file:

  <mvc:interceptors>
       <bean class="org.springframework.mobile.device.DeviceResolverHandlerInterceptor" />
       <bean class="org.springframework.mobile.device.site.SitePreferenceHandlerInterceptor" />
  </mvc:interceptors>

In order to dependency inject:

org.springframework.mobile.device.site.SitePreference
org.springframework.mobile.device.Device

into your Spring MVC controllers, you need to add custom argument resolvers:

<bean class="org.springframework.mobile.device.DeviceWebArgumentResolver" />

<bean class="org.springframework.mobile.device.site.SitePreferenceWebArgumentResolver" />

See Chapter 2.4.4 of the Spring Mobile documentation for details. An interesting observation: If you're using the site preference feature, you probably only need to inject: org.springframework.mobile.device.site.SitePreference
into your controllers. For example if users don't explicitly set the site preference through the request parameter ('currentSitePreference'), SitePreference will fall back to what Device would tell you.

I like the documentation change that instead of using a CustomWebArgumentResolverInstaller, the documentation now configures the resolvers directly in the context, which makes things easier to understand. I am impressed that with the M3 release the documentation looks very good.

Oh and in case you wondered how it works in practice - Check out http://www.devnexus.com/

It is admittedly (volunteer-) work in progress but I think the site preference feature is working nicely for my project now. Next, I need to beef up my jQuery Mobile skills to mobile-web-enable the entire site.

Marshal Json data using Jackson in Spring MVC with Jaxb Annotations

2011-01-25T01:15:00.015-05:00

The title is quite a mouthful but let me explain...For the DevNexus.com website I want to provide the website's data not only via XML but also via JSON in order to provide maximum flexibility for other consuming services. E.g. Pratik Patel pinged me the other day that he intends building an IPad client and Charlie Collins is planning to update his DevNexus Android client, which he originally created for the 2010 conference (The pressure is on gentleman ;-).

The DevNexus website is based on Spring MVC 3.0 and provides RESTful Urls that render Html views of the data (Targeting traditional browser clients as well as mobile client using Spring Mobile and jQuery Mobile).

Thus, I configured Restful endpoints as described in my last blog post. The easiest way to marshal JSON in Spring MVC is via the Jackson Java JSON-processor. Spring has a few documentation pointers regarding that. Theoretically, the setup is fairly simple and in its simplest forms means to just put the Jackson jar file onto your class path and adding mvc:annotation-driven to your Spring Xml Context file (See Chapter 15.12.1 of the Spring documentation). No sweat.

To get started more specifically with Jackson, here are some blog entries that I came accross while diving deeper into it:

While the tutorials may make you think that serializing JSON is happening defacto automatically, it turned out, that I had to fine-tune my domain model for Jackson. My domain model objects have bi-directional relationships and and I was getting a ton of errors of type:

java.lang.StackOverflowError - org.codehaus.jackson.map.JsonMappingException: Infinite recursion (StackOverflowError)

You can configure Jackson's marshalling behavior by annotating your domain model objects. However, those annotations are Jackson specific and I already was annotating my obejects with Jaxb annotations for the Xml marshalling of data.

Well - cool beans - , it turns out, Jackson can indeed use Jaxb annotations to renders Json data (added with version 1.1 of Jackson).

But how do I configure Jackson? How do I make it work in my Spring environment? I came across 2 blogs, that combined, provided the necessary solution.

The first example I found here, which provides a really nice example.

Furthermore, I not only wanted to configure Jackson to use Jaxb annotations, but I also needed to make it work for my Spring environment. For that Kyrill Alyoshin has some good information on his blog (
He also details how to make Jackson work better with Hibernate, which sounds interesting and I may return to his blog entry more specifically for that.).

Basically the best way to integrate Jackson and Spring is to create a custom ObjectMapper class that enables Jaxb support and which can then be injected into Spring's MappingJacksonJsonView.

Here are the things that were needed to get things going for my project -

First, add the following Maven Dependencies (jackson-xc provides the additional Jaxb support):

<!-- Jackson JSON Mapper -->
 <dependency>
     <groupId>org.codehaus.jackson</groupId>
     <artifactId>jackson-core-lgpl</artifactId>
     <version>1.6.4</version>
 </dependency>
 <dependency>
     <groupId>org.codehaus.jackson</groupId>
     <artifactId>jackson-mapper-lgpl</artifactId>
     <version>1.6.4</version>
 </dependency>
 <dependency>
     <groupId>org.codehaus.jackson</groupId>
     <artifactId>jackson-xc</artifactId>
     <version>1.6.4</version>
 </dependency>

The custom ObjectMapper:

import org.codehaus.jackson.map.AnnotationIntrospector;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.xc.JaxbAnnotationIntrospector;

public class JaxbJacksonObjectMapper extends ObjectMapper {

 public JaxbJacksonObjectMapper() {
  final AnnotationIntrospector introspector
      = new JaxbAnnotationIntrospector();
  super.getDeserializationConfig()
       .setAnnotationIntrospector(introspector);
  super.getSerializationConfig()
       .setAnnotationIntrospector(introspector);
    }

}

The SpringContext configuration that wires everything together:

    <bean class="org.springframework.web.servlet.view
        .ContentNegotiatingViewResolver">
        <property name="order" value="1" />
        <property name="ignoreAcceptHeader" value="true" />
        <property name="mediaTypes">
            <map>
                <entry key="xml"  value="application/xml"/>
                <entry key="json" value="application/json"/>
            </map>
        </property>
        <property name="defaultViews">
            <list>
                <bean class="org.springframework.web.servlet.view
          .xml.MarshallingView">
                    <property name="marshaller" 
                      ref="jaxbMarshaller"/>
                </bean>
                <bean
                    class="org.springframework.web
.servlet.view.json.MappingJacksonJsonView">
                    <property name="objectMapper"
 ref="jaxbJacksonObjectMapper"/>
                </bean>

            </list>
        </property>
    </bean>

REST with Spring - ContentNegotiatingViewResolver vs. HttpMessageConverter+ResponseBody Annotation

2011-01-21T00:10:00.002-05:00

Disclaimer: This blog posting reflects experiences while learning to implement RESTful services. Thus, certain elements of my blog posting may turn our to be not correct. Therefore, if you encounter errors, please let me know and I will post corrections as soon as possible. Please proceed with caution...

As I posted in my previous blog "Making DevNexus.com more Restful", I am in the process of making more of the data from DevNexus.com consumable by other services, by exposing JSon and XML based endpoints. The website/application is implemented using Spring MVC 3.0 in the view layer using Spring's REST support.

Here are a few good reads that I came across that provide some helpful information:

As it turns out, there are 2 ways of implementing REST endpoints:

use a ContentNegotiatingViewResolver
use HttpMessageConverters in combination with the @ResponseBody annotation

Using a ContentNegotiatingViewResolver

When you use a ContentNegotiatingViewResolver your web controllers return ModelAndViews or view names and the ContentNegotiatingViewResolver will, based on various criteria, choose the right data representation strategy.

The highest priority hereby has the file extension which is used if available in the request. Next, the ViewResolver will look for a (definable) request parameter that identifies the view. If that does not help, the ViewResolver uses the Java Activation Framework to determine the Content-Type. If all fails, use the the HTTP Accept header. Of course the steps can be individually disabled.

A key takeaway though is, that your controllers will return a single ModelAndView/Viewname that will resolve into a specific view such as:

org.springframework.web.servlet.view.json.MappingJacksonJsonView

org.springframework.web.servlet.view.xml.MarshallingView

org.springframework.web.servlet.view.documentClass.AbstractPdfView

```
etc...
```

However, this may feel a little unnatural for certain data representations such as XML (using Jaxb annotations) or Json (using Jackson), where a dedicated view may not be necessary. Luckily, you can configure the ContentNegotiatingViewResolver to use default views which kind of solves the issue.

Using HttpMessageConverters

This is where HttpMessageConverters potentially could help. Whenever you use the @ResponseBody annotation you will be using a HttpMessageConverter (See also the Spring reference documentation, chapter "15.3.2.5 Mapping the request body with the @RequestBody annotation" and "18.3.2 HTTP Message Conversion").

What this means is, that instead of returning a ModelAndView or view name, you will actually return data, e.g. a Collection of Objects.

If you use the Spring Context <mvc:annotation-driven/> then support for XML and JSON marshalling is activated by default, provided the respective class libraries (Jaxb and/or Jackson) are present in your class-path (See the Spring documentation for details at chapter "15.12.1 mvc:annotation-driven")

Here is the interesting problem, if you use <mvc:annotation-driven/> you can set additional conversion services but you cannot set additional HttpMessageConverters. Consequently, if you want to do that then you have to use explicit bean declarations and remove the <mvc:annotation-driven/> tag from your context. This was something not too well covered in article [6] http://www.ibm.com/developerworks/web/library/wa-restful/

Ultimately, I am using the following bean declaration instead of the <mvc:annotation-driven/> tag:

     <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
        <property name="webBindingInitializer">
            <bean class="org.springframework.web.bind.support.ConfigurableWebBindingInitializer">
                <property name="conversionService" ref="conversionService"/>
                <property name="validator" ref="validator"/>
            </bean>
        </property>
       <property name="messageConverters">
           <list>
               <ref bean="jsonConverter" />
               <ref bean="marshallingConverter" />
               <ref bean="atomConverter" />
           </list>
       </property>
    </bean>

My choice

This was a bit tricky. Both approaches are somewhat overlapping and I wish the documentation would give you better guidance on which approach to use under which cicumstances. Certainly the ContentNegotiatingViewResolver option seems to be the better documented solution. On the other side, you don't need to configure explicit views when using HttpMessageConverters and the ResponseBody annotation and therefore, that setup looks a bit more streamlined.

One issue I was running into was, that for my application I can return both pure data views (Json, XML) and also Html/Jsp responses. Somehow I was not able to configure my controller easily+cleanly, to respond to the same Url with multiple controller methods (one using @ResponseBody and the other returning a JSP view)

Secondly, I wanted to also support file extensions to use the correct view or converter. As it turns out though, HttpMessageConverters don't support that - Although there was an example somewhere for using request parameters. But that approach would require me creating additional custom classes...

Anyway, I went ahead chose the ContentNegotiatingViewResolver approach to implement my Restful services.

Further issues

Once I made my decision, everything seemed to go smoothly. I got my services implemented quickly and they worked perfectly in Firefox. Here is an example of the intended Url structure:

http://www.devnexus.com/s/speakers
http://www.devnexus.com/s/speakers.html
http://www.devnexus.com/s/speakers.xml
http://www.devnexus.com/s/speakers.json

With that I thought to have covered all bases: Support file extensions, but also allow clients to connect to http://www.devnexus.com/s/speakers and retrieve all data representations using the respective Http Accept header.

I deployed the app into production, but then the next day at the monthly Atlanta Users Group meeting - people informed me that the DevNexus site were down. That was odd, as I had accessed the site just minutes prior to the meeting.

Well, as it turned out, Google Chrome, Safari and Internet Explorer transmit a wild mixture of Http Accept headers. Consequently, when users accessed http://www.devnexus.com/s/index then the server would try to return an Xml view because Chrome and Safari requested Xml data rather than Html data.

For more details on Accept headers, please see the following fascinating:

http://www.gethifi.com/blog/browser-rest-http-accept-headers

What also threw me off, was that quite a few sources, incl. the Spring documentation imply that using the Http Accept header might be a actually a viable way of determining the correct view to return to clients.

To illustrate the chaos -Here is an interesting posting from the webkit mailing list:

https://lists.webkit.org/pipermail/webkit-dev/2010-January/011188.html

Ultimately, I got my servlet context configured in a way I think works best for me, though. The extension-less Url will always return Html now and for other data representations the file extension is mandatory. I also configured the ContentNegotiatingViewResolver to ignore Http Accept header by setting:

<property name="ignoreAcceptHeader" value="true" />

Many thanks to this blog posting by Rick Herrick. Thus, now my servlet-context.xml file contains:

    <bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="order" value="1" />
        <property name="ignoreAcceptHeader" value="true" />
        <property name="mediaTypes">
            <map>
                <entry key="xml"  value="application/xml"/>
                <entry key="json" value="application/json"/>
            </map>
        </property>
        <property name="defaultViews">
            <list>
                <bean class="org.springframework.web.servlet.view.xml.MarshallingView">
                    <property name="marshaller" ref="jaxbMarshaller"/>
                </bean>
                <bean
                    class="org.springframework.web.servlet.view.json.MappingJacksonJsonView">
                    <property name="objectMapper" ref="jaxbJacksonObjectMapper"/>
                </bean>
            </list>
        </property>
    </bean>

    <bean class="org.springframework.web.servlet.view.BeanNameViewResolver">
        <property name="order" value="2"/>
    </bean>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
        <property name="order"  value="3"/>
    </bean>

That was a rather long day to get things working as intended but a good learning experience nonetheless. There is certainly something intriguing about having clean Urls.

Review Starfish Reef Resort, Bocas del Toro, Panama

2011-01-19T22:49:00.000-05:00

Ourfamily of four stayed at Starfish Reef for three and a half weeks atthe end of 2010. We have two small children, ages two and threemonths. There were several things about our stay that were verynice, such as:

Our hosts, Jack and Kelly made dinner for us twice
Jack and Kelly called water taxis for us whenever we asked
A few times Jack drove us in his water taxi to places we requested(for a fee), and soon after we first arrived he took several hours toshow us around Almirante and help us with our shopping there
Jack picked us up in his mule (a small ATV) the last few days of ourtrip. For the first three weeks of our stay it was unavailable
The snorkeling on Starfish Reef was very nice, and we saw an octopus,a manta ray, and lots of small fish
Jack and Kelly installed a safety latch on the outside door of theroom our two year old slept in
Jack and Kelly recommended a lovely hotel in Panama City for our staythere, as well as a local tour guide who was knowledgeable andhelpful

However,we would not recommend Starfish Reef for several reasons, including:

-Shepherd Island, where Starfish Reef is located, has a terriblechitra (sand fly or no-see-ums)problem. However, Starfish Reef only offers mosquito nets forsleeping. Importantly, chitras are much smaller than mosquitoes, sothe nets do not provide much if any coverage from chitras. Jack andKelly do recommend using smoke coils to keep the chitras away (whichwe bought at our expense). These smoke coils do work well, however,it is a very heavy smell and not something we were pleased to usearound our children, much less ourselves. Wewere very irritated that readily available finer chitra-repellingnetting wasn't used for the beds. And no netting was provided forour son's crib initially, we had to ask for it.

-Internet is very important to us, since my wife has her own business,and I work in the IT field. We specifically asked aboutinternet coverage when deciding where we would stay in Bocas delToro. Jack and Kelly informed us that their internet is in all ofthe houses. However, we had hardly any internet coverage for thefirst week we were guests at Starfish Reef. Gunnar repeatedly spokewith Jack about it, and Jack finally had it fixed approximately oneweek into our vacation. However, even then, it was not throughoutour house. It was only available in certain parts of the house,excluding the living room and most of the main bedroom. And evenonce it was fixed, it still had almost daily outages.

-Jack and Kelly charge $6 for each load of laundry. Since weoriginally were going to stay with them for five weeks (more on thatbelow), and since we have two small children, we were doing personallaundry twice a week. One garnet was ruined in each of our firstseveral loads of laundry. We ended up losing five garments - fourpieces of clothes and a crib sheet that we had for over two years,and which was now far too small to fit the pack and play. We did notdo the laundry, it was done for us. After a new shirt given to ourdaughter was ruined (it had a hole in it that three pencils would fitthrough), we approached Jack about it. He said that he was awarethat the washing machine had some problems, and he showed us thefilthy shirt he was wearing as further proof of this. This boggledour minds. If he knew that his washing machine was not workingproperly and was in fact ruining clothes, why did he not previouslytell us? And how could he charge us for this service?! And Jackactually suggested that we place a patch on our daughter's shirt tocover up the hole! When we told Kelly about our ruined items, shetold us that we should not have brought nice clothes with us onvacation! When we told her that t-shirts and baby onesies are not"nice clothes", she had no response. And when we showedher a t-shirt of Gunnar's that had a large stain on it after theywashing it, she said that it looked like it was worn already. Yes,Kelly actually said this to paying guests.

-Jack and Kelly provided us with written information which stated"Taxi Service: Bocas Marine Tours $8pp each way to Almirante orBocas to and from Shepherd Island (minimum 2 persons or $16) until 6pm. Night taxi service with Fabian." They neglected to tell usthat Bocas Marine Taxi (BMT) may refuse to go to Shepherd Island ininclement weather. We learned this the hard way. One afternoon wearrived at the taxi port at 5:45pm expecting to make the 6pm taxi. Instead, we were told that the last water taxi had left around 4pmdue to the inclement weather. We ended up paying $60.00 for aprivate taxi to take us back to Starfish Reef. The same trip withthe water taxi service would have been $16.00 for all of us. Jackand Kelly had no response when we told them of this incident. Whenwe were leaving Starfish Reef, Jack repeatedly said that they couldnot be expected to tell us about all of the issues we may haveencountered while were were their guests. However, common sensedicates that they would have told us if the taxi service did nottransport during inclement weather.

-Shepherd Island is about a 20 minute boat ride from Bocas del Toro ingood weather. As stated above, Starfish Reef has, or had, a dealwith BMT to transport its guests. This worked fine in good, andrelatively good, weather. However, when the weather was poor, BMTdid not want to come out to Starfish Reef. On at least twooccasions, BMT said that it was not sure that it would be able tocome out to pick us up. It did come out, but not at the stated timesand much earlier than expected. We kept the taxi service waitingthese two times because it arrived 10-15 minutes early. Thereafter,beginning on December 15^th,BMT refused to pick us up. Jack and Kelly told us that the servicetold them that it was because we kept them waiting (which Jackexplicitly told us he knew was not fair), and when we personallyasked BMT, we were told that it was because of the inclement weatherand the dangers it posed. Notably, BMT makes several trips duringthe day between Bocas del Toro and Almirante. Both locations provideit with several passengers. Going to Starfish Reef in bad weather,for two paying customers, likely was not worth the time, gas andpotential danger. Regardless, the sudden lack of taxi service was asevere problem for us since it was our means of transportation. Whenthis happened, Jack offered to bring us to Almirante to pick up BMTthere. However, this would have increased our trip times by morethan double, since Almirante was a 15-20 minute ride in Jack's boat,and we would then have to wait for the water taxi. So, a 20 minutetrip would become a 45-50 minute trip, each way.

-We repeatedly had to remind Jack that our house needed weeklycleaning, and had to specifically ask that our linens be washedweekly. These are service that Jack and Kelly previously told uswere included.

-Several of the steps leading to and from the dock to the houses arewashed out. Since it is a fairly steep walk, and since we werewalking it almost daily with two small children, we were disappointedthat the steps were in such deteriorated and potentially dangerouscondition.

-The written information provided to us by Jack and Kelly on the daywe arrived states that they charge $10.00 per couple to go to RanaAzul, a restaurant about twenty minutes by boat. We were insteadcharged $16.00 per couple. We only learned that we were to have beencharged $10.00 after we re-read the paperwork several days into ourstay. If there was a rate change, we should have been informed ofthis prior to taking the trips.

-Jack invited us to join him for Thanksgiving dinner at Rana Azul. Immediately before the dinner was an at sea funeral for a friend andneighbor of his who recently passed away. Jack was going directlyfrom the funeral to Rana Azul. Jack asked us several times if wewould like to join him for both events. We had nothing else plannedfor the day, and since it was Thanksgiving, we agreed. After thedinner, Jack then asked us for $16.00 as our fare to Rana Azul (whichshould have been $10.00). Not once previously did he mention thatthere would be a charge. This annoyed us since he had severalopportunities to tell us that he would charge us, AND because it wasclear that he was going to the funeral and dinner afterwards with orwithout us. It certainly made us feel that we were being nicked anddimed by Starfish Reef.

-Jack and Kelly offer several excursions, with rates ranging from$20.00 to $550.00. We asked that they take us on the chocolate tourat Green Acres Farm no fewer than five or six times before theyscheduled a visit for us. Notably, this is their cheapest excursion.

-The website states that the property has "a working greenrainforest and Cacao plantation". This led us tobelieve that the property contained a cacao plantation. It does not. It has cacao trees, but no working cacao (or chocolate) plantation.

-The two-way radio between our house and Jack and Kelly's house oftendid not work because, as Jack and Kelly said, their radio "needednew batteries." We would then communicate by yelling to eachother from the porches of our houses.

Weoriginally planned to stay at Starfish Reef for five weeks, and weprepaid for five weeks. We decided to leave Starfish Reef five daysearly, on December 20^th,because we were very disappointed with our lodgings and the property,and because we were spending so much time there due to the very rainyweather. If the weather was better and we were out of the house andoff the island more, many of the problems stated above would not havebothered us as much. We asked for a refund for those five days, andwere told that we would not get one because, as Jack said, "singlyor collectively", the issues we raised did not qualify for arefund. We were shocked by this response in light of all of theproblems we had during our stay.

Weended up leaving five days earlier than that because, on December15^th,both BMT stopped coming to Starfish Reef (as per the above), andbecause there was no water in our house. Jack had installed a newvalve on the water pump on December 14^th. The water was leaking for several hours after Jack's installation. We were gone that afternoon, and when we returned in the earlyevening and heard running water, we tried reaching Jack and Kelly totell them that we thought there was a problem. We tried them on thetwo-way radio beginning at approximately 6pm. No one answered. Wetried off and on until 11pm, but there was no answer. We also yelledfor them from our balcony, to no avail. The next morning we wokethem up at 6:30am by yelling at them from our balcony. When we toldthem that we had been trying to reach them all evening and into thenight, Jack said that he turns off the two-way radio at night(meaning that we have no means of communicating with our hosts atnight). When we told him that we tried reaching him in the earlyevening, he had no response. He later repeatedly asked us if we usedup all of the water. We told him that we did not, that we were gonethat afternoon, and that we heard the pump running for several hoursand kept trying to inform him of it. It was evident to us that theproblem likely stemmed from the work Jack did on the pump earlierthat day, but he sought to blame us instead.

Twocomments in closing. What bothered us the most was that Jack andKelly did not accept responsibility for obvious problems at StarfishReef - their laundry machine not working properly, their internet notworking and/or not working throughout the entire house, the waterpump, etc. They never once said "We're sorry, how can we makethis up to you?" We travel quite a bit and usually do not haveany complaints. Here, we were faced with many problems at StarfishReef that made our stay far less enjoyable, and when we raised theseissues, Jack and Kelly's response was always to deflect it back ontous.

Secondly,we would not recommend this property for a family or for anyonestaying for more than a week. However, if the internet is notimportant to you, you are not doing a laundry, chitras don't botheryou much, and BMT is traveling again to Starfish Reef, etc., you mayenjoy this property. There is a lot of beauty there and the housesare spacious and modern. If you are looking to get away for a fewdays to a week and aren't bothered by what we wrote above, this maybe the place for you. But for us, it was clearly far less than wewere led to believe we would find. We were over-promised, and werevery disappointed to find a dilapidated property, with hosts who donot take responsibility for problems on their property.

AlysaFreeman and Gunnar Hillert, January 2011.

Making DevNexus.com more Restful

2011-01-18T01:00:00.029-05:00

A few people had ask me, whether I can make the data of DevNexus.com consumable for other clients (e.g. Android or iPhone). Sure, no sweat - As I expose the URL in a somewhat RESTful fashion already, I thought exposing a variety of different data representations is not hard but it turned out to be a bit more tricky than I thought but I will blog about that in the next 1-2 days or so.

Under the covers I am using Spring MVC 3.0 that provides the Rest infrastructure, Jackson for the Json marshalling and Jaxb for marshalling the XML data.

First of all, here is what I have accomplished: The page that returns a list of presentations and the page that returns a list of speakers, will both return the data in either XML or JSON as well. Bear in mind this is still a fairly rough cut and the data representation may still change quite a bit.

Anyway, these are the exposed endpoints so far:

http://www.devnexus.com/s/presentations
Returns any of the other following 3 data representations depending of the Accept Http header. (However, a defined file extension always wins over the Accept header.)

http://www.devnexus.com/s/presentations.html
http://www.devnexus.com/s/presentations.xml
http://www.devnexus.com/s/presentations.json

http://www.devnexus.com/s/speakers
Returns any of the other following 3 data representations depending of the Accept Http header. (However, a defined file extension always wins over the Accept header.)

http://www.devnexus.com/s/speakers.html
http://www.devnexus.com/s/speakers.xml
http://www.devnexus.com/s/speakers.json

As Accept headers the following values are acceptable and handled right now:

application/xml
application/json
text/html

For testing the Firefox plugin "Rest Client" works really well: https://addons.mozilla.org/en-US/firefox/addon/restclient/

As mentioned above, I will blog about the technical details and encountered issues in the next couple of days. Also, if you try to consume the data and run into issues and or have suggestions - ping me and add a comment!

Spring Mobile, jQuery Mobile and SiteMesh

2011-01-04T01:01:00.001-05:00

I just realized that I haven't published a blog entry in a while. Time just flies by. Anyway, I am in the midst with several other volunteers to prepare for the Atlanta-based DevNexus developer conference which will take place March 21-22.

For this year's conference I reworked the conference website application using Spring (MVC) 3.0, JPA 2.0 etc. In addition to standard clients, I started looking into supporting mobile clients as well.

My requirement was to provide a decent looking mobile interface in a reasonable amount of time (heck, it is all done during my spare-time afterall). Plus, I wanted to support multiple mobile devices at once. Out of that reason I ruled out a native client implementation (at least for now).

Another option, would have been to look at other development frameworks such as PhoneGap and Appcelerator, something I may still have to do down the road.

As I have been using jQuery quite a bit, I started exploring it using either jQTouch or jQuery Mobile. I opted into looking at jQuery Mobile as it is the official jQuery sanctioned project.

As it turns out, you can easily create create some nice looking UIs using jQuery Mobile. As an example, just point, your mobile browser, e.g. Android to http://www.devnexus.com/. This is pretty impressive considering that I have been using an Alpha 2 version with just standard theming and functionality.

I still have to work on the detail pages, but the main landing page looks fairly nice out of the box using minimal amounts of code.

On the server-side, I am using Spring Mobile, which currently is available as a M2 release. What Spring Mobile allows you to do is to detect from within your Spring MVC controllers, whether the incoming request originates from a mobile device or not.

If you need to detect specific device capabilities, you can even use a WurflDeviceResolver, but for my use case I simply need to know whether a mobile device request is coming in or not. If so, forward to a mobile version of the respective controller's jsp page.

One, question I had to solve was how to make everything work with SiteMesh, which I use for templating purposes. As I use the same Urls for mobile and standard clients (No site-switching), I ended up needing to create a custom SiteMesh DecoratorMapper extending AbstractDecoratorMapper.

public class SpringMobileParameterDecoratorMapper extends AbstractDecoratorMapper {
    private String decoratorName = null;

    public void init(Config config, Properties properties, DecoratorMapper parent) throws InstantiationException {
        super.init(config, properties, parent);
        decoratorName = properties.getProperty("decorator.name", "mobile");
    }

    public Decorator getDecorator(final HttpServletRequest request, final Page page) {

        final Device device = DeviceResolverHandlerInterceptor.getCurrentDevice(request);

        if (device != null && device.isMobile()) {
         return getNamedDecorator(request, decoratorName);
        } else {
         return super.getDecorator(request, page);
        }

    }
}

It may not be the bestapproach to have a hard dependency onto Spring Mobile in my SiteMesh DecoratorMapper...but it works nicely so far.

Google, Oracle and JUGs

2010-08-18T08:00:00.001-04:00

One might think that developing software (web-applications in my case) is a pretty involved endeavor. It is a constant learning experience: from understanding the business domain of your customers for each and every project, to figuring out which frameworks to choose (How many web-frameworks to we have?), all the way to understanding the broader IT landscape.

Thus, in a nutshell life as a developer is busy...and then Oracle sues Google, adding just a tad more complexity to the mix (Things were also much easier back when it was all about Microsoft versus he rest of the world :-). Additionally, as the leader of the Atlanta Java Users Group, I wonder what kind of implication this development will have for our community of Java developers.

Following the various information sources, there is certainly no black-and-white battle going one, albeit Google seems to be certainly in a more favorable position among developers. A good source for gauging the mood within the Java community is to follow the mailing list of the global JUG community. Sentiments there have been ranging from surprise to shock.

Bruno Souza, THE Java advocate in Brazil (he also spoke at AJUG in Atlanta in May 2007) made probably the most balanced statements regarding the just started litigation process between Oracle and Google. Thus, from a technical/legal perspective you may very well argue in either direction, in favor of Google or in favor of Oracle.

However, I am concerned about the impact this may have in regards to our community and the leading edge open-source developers, that may again increasingly look elsewhere (Remember the wave of developers that left for Ruby on Rails a few years back?).

I will cautiously follow the developments over the next couple of months and I hope that the negative impact to our community can be minimized. I mean, there is certainly the hope that Oracle and Google come to a quick agreement and maybe make Android an official part of the Java platform (too overly optimistic?)

Here are some pointers for further information:

InfoQ had a short article summarizing the latest developments: http://www.infoq.com/news/2010/08/oracle_sues_google

Javalobby has an insightful article regarding Oracle's open-source activities, e.g. essentially shutting down OpenSolaris: http://java.dzone.com/articles/oracle-and-open-source-list

JavaWorld takes it even a step further and ask whether SpringSource should be worried as well: http://www.javaworld.com/community/?q=node/4919

Many high-ranking Java advocates left Oracle in recent months, and Java inventor James Gosling is becoming increasingly outspoken. His blog provides some interesting insights:

http://nighthacks.com/roller/jag/entry/the_shit_finally_hits_the
http://nighthacks.com/roller/jag/entry/quite_the_firestorm
http://nighthacks.com/roller/jag/entry/cynical_chuckles

(Interestingly, looks like too many people were trying to read read James Gosling's blog on 2010-08-16 because his blog was not accessible for a good portion of the day)

The following link points to an official statement by Oracle regarding its patent policy in 1994. Things seemed to have changed since then, unfortunately:

http://www.bustpatents.com/articles/oracle.htm

Function based indexes in Oracle

2010-08-11T10:50:00.000-04:00

If you ever have to query tables in Oracle containing million of records using "is null" in the where clause, then you will notice that your normal indexes won't kick in. They work as prescribed for "is not null", though.

Using a function-based index you can work around that issue. Take a look at the following article which might be quite helpful if you run into the issue:http://www.dba-oracle.com/oracle_tips_null_idx.htm

Using Hibernate's SchemaExport Feature from within a Spring/JPA Context

2010-05-06T02:00:00.000-04:00

My Spring-based application uses the Java Persistence Api (JPA) with Hibernate as persistence provider. As business requirement, I have the need to generate the SQL schema from my JPA annotated classes at application startup (As a disclaimer: I used the Maven Hibernate3 plugin in the past and there is also an Ant task provided by Hibernate, however in my case I needed a programmatic approach to have some more flexibility). Anyway, A logic choice for this would be Hibernate's SchemaExport class.

The problem is that Hibernate's SchemaExport class requires a org.hibernate.cfg.Configuration class to be passed in. Configuring this within Spring based applications is sparsely documented (Furthermore, the Configuration class is not easy to get hold off) but nevertheless there are some good pointers on how to get the Configuration object, when using straight Hibernate e.g:

http://forum.springsource.org/archive/index.php/t-65818.html

Unfortunately, I am a bit on the cutting edge and I configured my persistence using

org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean and
org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter

How do you make that work? The best, albeit limited, information I found (as usual) on Stackoverflow:

http://stackoverflow.com/questions/297438/auto-generate-data-schema-from-jpa-annotated-entity-classes

That discussion pointed to the following blog post:

http://jandrewthompson.blogspot.com/2009/10/how-to-generate-ddl-scripts-from.html

That was pretty much it. The blog post gave me some ideas about where to look next for answers (the Hibernate and Spring source code ;-), but the example just felt a bit heavy for my use-case. Everything was already configurred using Spring/JPA in my environment. Why shouldn't I be able to reuse my existing infrastructure to use the SchemaExport class?

The solution

After some more searching, I think I found a workable example:

In my class I inject the LocalContainerEntityManagerFactoryBean:

@Autowired LocalContainerEntityManagerFactoryBean fb;

Then I use the following code to setup SchemaExport:

org.hibernate.ejb.Ejb3Configuration cfg = new org.hibernate.ejb.Ejb3Configuration();
org.hibernate.ejb.Ejb3Configuration configured =

                 cfg.configure(fb.getPersistenceUnitInfo(), fb.getJpaPropertyMap()); org.hibernate.tool.hbm2ddl.SchemaExport schemaExport =

new org.hibernate.tool.hbm2ddl.SchemaExport(configured.getHibernateConfiguration());

And then do whatever you need to, such as printing the SQL Schema DDL to the console:

schemaExport.create(true, false);

Not that bad after all. If you have similar needs, hopefully the Google gods are with you and this blog posting showed up in your search results. See you next time.

Martin Fowler in Atlanta - DSLs, Agile, CI

2010-04-29T10:57:00.001-04:00

I went to Martin Fowler's talk last night night at the Crowne Plaza Hotel next to Perimeter Mall. Martin Fowler is the Chief Scientist at ThoughtWorks and it has been a great experience to finally hear him speak personally. He have three mini presentations:

His first talk was about domain specific languages (DSL) covering all the different variation of DSLs - external DSLs (XML, custom language) and internal DSLs (e.g Ruby). Martin Fowler also had a slide about Language Workbenches - I saw an article on his website covering that subject, which I need to look at in the next few days.

An interesting point I thought he raised was, to focus on making codified business concerns "readable" through DSLs rather than making the DSL available to business people to write rules, business logic etc. as this would be so much harder to achieve.

In his second presentation segment, Martin Fowler answered questions, that were submitted by the audience prior to his presentation, which covered various aspect of agile software development. He mentioned that the British newspaper The Guardian, is releasing software changes into production every 2 weeks.

The way to achieve this is through total test automation. He mentions that at Thoughtworks manual QA is reduced to exploratory testing and that any test plans etc. are part of the automated build process (More details about this at the end of this blog post)

A popular question these days also seems to be whether Java has peaked and whether also languages shall be considered. Martin Fowler, stated that "Java stalled" but it is not going away. However, he also pointed to the fact, that you should consider more productive languages (especially for new projects). He mentioned an internal and informal Thoughtworks survey in which developers on average attested a 0.5-2.5x increase in productivety when using alternative languages (Ruby, Groovy, Scala, Clojure etc.). Martin Fowler himself expressed his preference for Ruby.

His last talk was about continuous integration and continuous delivery. He talked a bit about different approaches regarding managing your source code in your respective source repository (e.g. Subversion). Specifically he talked about having feature branches versus just a single trunk (for the most part). It was interesting to hear him talk about that as at work we recently had that same discussion and we finally settled on having just a single trunk for all our regular development efforts. He said feature branches are just too painful when doing merges.

Moving on, he suggested to commit your code at least once a day, preferably even more often.

He then talked about continuous delivery, meaning to continuously push code into production in a controlled fashion. He mentioned a Suisse Insurances company that would deploy code into production once a day. As far as I remember he said that at Thoughtworks they typically deploy into production every two weeks to once a month.

In order to achieve that you must have really good automated testing at which point Martin Fowler talked about having a "build pipeline" which consists of the following phases:

Commit Stage - Build project run tests (unit-tests), execution shouldn't take longer than 10 minutes. Deploy artifacts to artifacts repository
Acceptance Stage - Deploy the application, run smoke tests, run acceptance tests. This stage may take much longer (e.g. 1-2 hours)
Performance Stage - Run Performance Tests - This may take a very long time
Deployment Stage - Deploy the application into production - It is important to be able to deploy by just pressing one button. However, have a rollback option

Then he talked a little bit about Cruise, Thoughtwork's product to help implement that kind of continuous delivery. There is also a book coming out from Addison Wesley called Continuous Delivery.

That basically conclded his talk - there was one further question from the audience that caught my attention. Chris Curtin (CTO of Silverpop) asked him about the Devops movement. Personally I was unaware of that term. In my understanding, this fairly new concept brings developers and operation teams closer together.

Martin Fowler found that concept to be a very positive thing saying that if a production issue was caused by a developer, he should carry the pager for that and fix it. I have to learn more about the Devops movement - here is an interesting blog entry that seems to summarize it quite well: http://www.jedi.be/blog/2010/02/12/what-is-this-devops-thing-anyway/.

A great evening - learned a lot.

Java Posse Roundup 2010 - Summary

2010-03-23T02:22:00.001-04:00

I am sitting in the plane right now returning back to Atlanta from Denver, Colorado. It has been an incredible week. As you may have seen my Twitter tweets, I spent last week at the Java Posse Roundup in Crested Butte, Colorado. It was simply amazing. Some of the brightest minds in our industry were there and the conference setting was very cozy with around 40 attendees. It was a very diverse crowd with attendees from all parts of the US (incl. 4 people from Atlanta and 1 from Nashville) as well as quite a few folks from Europe (UK, Denmark, Norway) as well as Israel.

James Ward was there (Flex Evangelist for Adobe), Bruce Eckel (Author of "Thinking in Java"), ???? Joe Darcy (Lead at Oracle for Project “Coin” [JDK7]), Bill Pugh (Findbugs) and many more.

Here are the sessions I attended at the Roundup:

Tuesday

NoSQL Databases
Apple and HTML 5 versus Flash (What Does the Future hold) and UI Framework experiences GWT vs Flex vs ?

Wednesday

Measurable ≠ Meaningful (Business)
Architecture standardisation
JavaFX - What else do we want?

Thursday

Alternative Views of SW Development (Convention over configuration, static vs. dynamic, Rockstar dependencies)
When companies transition from awesome to sucky corporate environments
Project Coin, JDK7, Language Evolution

Friday

Source Control Systems (Server based (SVN) vs. Distributed VCS (Git, Mercurial)
When the wheels come off agile
Share your IDE/Editor tips and tricks

On Tuesday and Wednesday, there were Lightning Talks. Every attendee could sign up for 5 minute mini-presentations on any topic (technical, personal, informational you name it). This was really cool. Did you ever attend an IT conference where you could see fire eating? Bill Pugh did it!!!

On Thursday, I did a lightning talk on YSlow and JAWR which I think went pretty well (considering that I only prepared for it 1 hour in the afternoon that same day).
Thursday night, the 300th episode of the JavaPosse was recorded. It has been a lot of fun. The podcast episode was released on Friday!

This was my first JavaPosse Roundup conference. I am sure that I will return next year. It was an incredible learning experience and a ton of fun! A massive THANK YOU to Dick Wall, Tor Norbye, Carl Quinn, Joe Nuxoll and Bruce Eckel for organizing this amazing experience!

DevNexus Day One

2010-03-09T00:37:00.000-05:00

Alright, this is just a super quick update on day one of our DevNexus conference. Day 1 went very smoothly with no major hick-ups. We have around 340 attendees (Incl. sponsors, speakers etc.), which constitutes a 40% growth compared to last year!!! Thanks to all that attended!

I attended the following sessions:

"Better Software with Java and Flex" (James Ward)
"Next Generation Development Infrastructure: Maven, M2Eclipse, Nexus & Hudson" (Jason van Zyl)
"Google App Engine: Cloud vs Cluster" (Toby Reyelts)
"The 90-Day Startup with Google AppEngine: A Case Study" (David Chandler)
"Effective Java" (Venkat Subramaniam)
"Smithing in the 21st Century" (Neal Ford)

The day finished off with a cocktail hour and I met some nice folks from The Home Depot and I spent the rest of the eventing chatting with the hard core of the crowd which involved mostly speakers such as Toby Reyelts, Charlie Collins, Barry Hawkins, James Ward, Pratik Patel and Greg Luck. After dropping Greg off at his hotel, I finally made it home right around midnight.

This has been a very good day. Time to get some sleep. See you all tomorrow at day 2!

DevNexus has its own Android App

2010-03-01T08:40:00.000-05:00

Pretty cool - Charlie Collins created the first Android phone app for the DevNexus conference. Check it out at: http://code.google.com/p/and-conference/. Thanks Charlie!

Also, in case you haven't registered for DevNexus, yet. Please sign-up because registration is closing March 3rd.

Atlanta DevNexus 2010 Conference - Status

2010-02-02T00:18:00.000-05:00

We at AJUG are humming along preparing for DevNexus (March 8-9, 2010). Today we got confirmation that Jason van Zyl from Sonatype is speaking at our event. He is the founder of Apache Maven and Sonatype. I added his bio and abstract to the website tonight. Thus, check out our presentation line-up for details.

Also, we got our very own Twitter account (Many thanks to Barry Hawkins for organizing this!!). Over the next few day I will add it to the DevNexus website and we will post noteworthy updates through that channel.

Thus, start following us at: http://twitter.com/devnexus/

Plaxo OpenID Recipe

2010-01-30T15:54:00.000-05:00

Plaxo was probably one of the first main sites where I saw OpenID support for your user credentials. But only today did I notice that they also have a really nice write-up of of their OpenID implementation, which could serve you as a guide/recipe for implementing your own OpenID supporting user registration process.

Check it out at: http://www.plaxo.com/api/openid_recipe

Automating User Registrations with OpenID and Spring Security 3.0 - Part 3

2010-01-27T00:15:00.014-05:00

Preparing heavily for DevNexus 2010, I did not have as much time as I hoped for in order to continue my series on using OpenID with the new SpringSecurity 3.0 (See Part 2 for details) Thus, today I would just like to cut and paste some of the code from my little 'home-POC'. In the coming weeks I still hope to incorporate it properly into jRecruiter.

Here is the JSP snippet for the OpenID login form:

<div id="openid-registration">
  <form name='oidf' action='/jrecruiter-web/j_spring_openid_security_check' method='POST'>
    <fieldset id="openIdLoginSection">
          <legend>Login with OpenID Identity</legend>
          <div class="required">
            <label for="openid_identifier">Identity</label>
            <s:textfield id="openid_identifier" name="openid_identifier" required="true" maxlength="80" tabindex="1" size="30"/>
          </div>
          <div class="submit">
            <input type="submit" value="Login"/>
          </div>
    </fieldset>
  </form>               
</div>

Here is the relevant piece of my Spring context file:

<security:http  auto-config="true" access-decision-manager-ref="accessDecisionManager" >
  <security:intercept-url pattern="/s/admin/**" access="ADMIN"                        requires-channel="https"/>
  <security:intercept-url pattern="/**"         access="IS_AUTHENTICATED_ANONYMOUSLY" requires-channel="any" />

  <security:form-login login-page="/login.html" default-target-url="/admin/index.html"
                       authentication-failure-url="/login.html?status=error" />
  <security:logout logout-url="/logout.html" invalidate-session="true" logout-success-url="/show.jobs.html"/>
  <security:session-management>
     <security:concurrency-control max-sessions="1" error-if-maximum-exceeded="false"/>
  </security:session-management>
  <security:custom-filter ref="openIDFilter"                   position="OPENID_FILTER" />
</security:http>

<bean id="openIDFilter" class="org.jrecruiter.web.security.RegistrationAwareOpenIDAuthenticationFilter">
  <property name="authenticationManager" ref="authenticationManager"/>
  <property name="consumer" ref="attributeAwareOpenIDConsumer"/>
  <property name="authenticationSuccessHandler"        ref="openIDFilterSuccess"/>
  <property name="authenticationFailureHandler"        ref="openIDFilterFailure"/>
  <property name="registrationTargetUrlRequestHandler" ref="openIDFilterRedirectToRegistration"/>
</bean>

<bean id="openIDFilterRedirectToRegistration" class="org.jrecruiter.web.security.RegistrationTargetUrlRequestHandler">
  <property name="defaultTargetUrl" value="/registration/signup.html"/>
</bean>
<bean id="openIDFilterSuccess" class="org.springframework.security.web.authentication.SimpleUrlAuthenticationSuccessHandler">
  <property name="defaultTargetUrl" value="/admin/index.html"/>
</bean>
 
<bean id="openIDFilterFailure" class="org.springframework.security.web.authentication.SimpleUrlAuthenticationFailureHandler">
  <property name="defaultFailureUrl" value="/login.html?status=error"/>
</bean>

<bean id="attributeAwareOpenIDProvider" class="org.jrecruiter.web.security.AttributeAwareOpenIDProvider" scope="prototype">
  <constructor-arg ref="userService"/>
</bean>

<bean id="attributeAwareOpenIDConsumer" class="org.jrecruiter.web.security.AttributeAwareOpenIDConsumer"/>

I did some customization:

public class AttributeAwareOpenIDConsumer extends OpenID4JavaConsumer {
  public AttributeAwareOpenIDConsumer() throws ConsumerException {
         super(Arrays.asList(UsedOpenIdAttribute.FIRST_NAME.getOpenIdAttribute(), 
                                     UsedOpenIdAttribute.LAST_NAME.getOpenIdAttribute(), 
                                     UsedOpenIdAttribute.EMAIL.getOpenIdAttribute(),
                                     UsedOpenIdAttribute.AX_FIRST_NAME.getOpenIdAttribute(),
                                     UsedOpenIdAttribute.AX_LAST_NAME.getOpenIdAttribute(),
                                     UsedOpenIdAttribute.NAME_PERSON.getOpenIdAttribute()));
  }
}

I also created a custom class AttributeAwareOpenIDProvider which extends org.springframework.security.openid.OpenIDAuthenticationProvider. It overrides public Authentication authenticate(Authentication authentication) Thus, I can hook into the actual authentication process and inject my own logic.

For example, if the OpenID authentication succeeds it does not necessarily mean that your account exists, yet. Therefore, if OpenID authentication succeeds (if (status == OpenIDAuthenticationStatus.SUCCESS)), I try loading the user from my application's database (userDetailsService). If then a UsernameNotFoundException is thrown I collect a series of OpenID attributes from the org.springframework.security.openid.OpenIDAuthenticationToken. Once finished, I am throwing a custom AuthenticationSucessButMissingRegistrationException. I use it to redirect to the registration page and pre-populate the registration form with some of the collected OpenID attributes.

I hope this gives you some ideas of how you can integrate OpenID into your SpringSecurity infrastructure. I am myself still in the early learning phase regarding OpenID and I still need to figure out how to best manage multiple authentication realms within my application. But that may be a reason for another blog post.

Remote Profiling of JBoss using VisualVM

2010-01-22T23:38:00.002-05:00

I ran into an issue while trying to setup profiling (using VisualVM) of a remote JBoss server instance. It turns out that the default steps I have found on the internet, assume that your target server (Where JBoss is running on) is accessible via the hostname not only by IP address. Well, just in case you live in an environment where you can access your server via IP but not via hostname, this blog post may hopefully save you an hour googling the solution. In order to setup remote profiling I did:

To my run.conf file (JBoss/bin) I added:

JAVA_OPTS="$JAVA_OPTS -Xdebug -Xrunjdwp:transport=dt_socket,address=8787,server=y,suspend=n"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.port=6789"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.ssl=false"
JAVA_OPTS="$JAVA_OPTS -Dcom.sun.management.jmxremote.authenticate=false"
JAVA_OPTS="$JAVA_OPTS -Djava.rmi.server.hostname=IP_ADDRESS_OF_MY_JBOSS"

Particularly, the last line was very important. Without it I was able to telnet to port 6789, thinking everything is cool, however I was unable to connect to it via VisualVM. This missing line caused a few frustrations.

Anyway, once these lines were added, you need to configure jstatd. I created a policy file (I called it tools.policy) for the JVM containing:

grant {
permission java.security.AllPermission;
};

Then, I would be able to start up jstatd:

jstatd -p 1099 -J-Djava.security.policy=tools.policy

And finally, I was able to startup JBoss and connect to my server from VisualVM.

Registration Opens for DevNexus 2010

2010-01-14T00:48:00.000-05:00

Here is an annoucement that I would like to get out regarding the Atlanta Java Users Group's (AJUG) professional developer conference:

The DevNexus conference will be held in Atlanta March 8–9, 2010 and registration is now open. DevNexus covers a wide range of the most exciting topics related to the Java™ platform.

This year, our sophisticated line-up of speakers covers dynamic programming languages such as Scala and Groovy, as well as Rich Internet Applications (RIA) such as Adobe Flex and Google Web Toolkit (GWT). Furthermore, we have a dedicated track on Google technologies, which not only covers GWT but also Google App Engine and Google Wave. Additionally, DevNexus has sessions covering popular open source projects such as Spring, Maven and HtmlUnit, as well as presentations on software architecture, agile software development methodologies and much more!

Please join us for this exceptional event.

The organizers of DevNexus are focused on making sure the conference provides the best possible educational value by offering attendees a special early bird rate of $150 if they register between now and February 16. Regular admission for the two-day conference is $185, a group discount is also available. The ticket price includes the two-day conference pass as well as meals.

This is the second DevNexus event, which is the continuation of the annual AJUG developer conferences that started in 2004.

For further information: http://www.devnexus.com/

DevNexus 2010 Conference Updates

2010-01-12T00:20:00.002-05:00

I have spent a few late nights lately, to get the preparations for the Atlanta DevNexus conference into the final stage. The line-up of speakers is getting fuller by the day. I am personally really excited that James Ward (Adobe), Keith Donald (SpringSource) and Lex Spoon (Google) are presenting and we have many, many more presenters covering a ton of material.

I will try my best to update the website (http://www.devnexus.com) with the current list of speakers and presentations, soon.

Which also reminds me to finalize our press-release to announce the conference...I hope to get all that done within the next 2 days. Thus, watch http://www.devnexus.com/ for updates. And please sign-up!
For that price, you won't get a better educational value (...brought to you by your friendly Atlanta Java Users Group)

Automating User Registrations with OpenID and Spring Security 3.0 - Part 2

2010-01-01T14:10:00.032-05:00

This is the continuation of part 1. See also part 3.

Spring Security provides support for OpenID out of the box. It is fairly easy to setup basic OpenID authentication. It even can automatically generate the respective login forms for you. But for my use case I wanted something more elaborate. Here is a basic flow of my "Spring Security OpenID integration solution" (early working draft):

Step 1: User starts the login process using OpenID.
Note that the 'OpenID' between providers varies quite a bit.

Google uses a generic login String that is the same for every user (http://www.google.com/accounts/o8/id)
MyOpenID has a unique URI identifier for each user (e.g. http://mysupercoolusernmae.myopenid.com/)

Step 2: After pressing the Login button, Spring Security processes the request and using openid4java under the hood, you are redirected to the login page of your OpenID provider in this case Google.

Step 3: In step 2 you authenticated successfully (with Google in this case), but you don't have a valid account with jRecruiter itself, yet: In this instance, grab all the useful information that is available through the OpenID account/profile and then forward (Redirect) to the registration page. There pre-fill the form with the grabbed information (E.g. email, first name, last name etc.)

Of course I need to add some more sophistication around my user registration process. Nevertheless, I hope the general flow is clear. While OpenID is a fairly widely adopted standard, there seems to be a bit of fluctuation in regards to what data sets providers will allow you to fetch, as well as how to fetch them (e.g. different name-spaces). Thus, it looks like in order to automated an OpenID-supported registration process, you need to be aware (code for) specific providers. I need to explore that area a bit more.

In my next posting I will finally provide some source code. If find some time, take a look and play around with openid4java. The OSS project provides various examples, and the 'simple-openid' example is really helpful for understanding the actual openID registration process. Stay tuned.

Automating User Registrations with OpenID and Spring Security 3.0 - Part 1

2009-12-27T17:48:00.004-05:00

Having a few days of vacation is nice. Besides spending some precious time with my family, it also gave me some time to work on jRecruiter. I upgraded Spring Security to the final 3.0.0 version, which was released just a few days ago.

The upgrade process was relatively painless, though it is not a simple Jar drop-in as the packages of many of the classes changed. But it was fairly straight-forward.

The biggest hassle, was upgrading Jasypt as the latest released version is not playing nice with Spring Security 3.0, yet. But the code is already committed to Jasypt's source code repository, and with minor modifications, I was able to compile a custom version.

But while I was looking through the changes of Spring Security 3, I started reading a little bit more about its support for OpenID.Which then let to the question, whether there is a good use case for OpenID in my home project.

Places where I saw the use of OpenID are:

Here is actually a pretty good blog post regarding OpenID:

http://www.codinghorror.com/blog/archives/001121.html

Security Concerns

Then of course, there are also a few security concerns regarding allowing for OpenID authentication:

If that's not enough:

http://stackoverflow.com/questions/tagged?tagnames=openid&sort=votes&pagesize=50

Thus, while I probably wouldn't use OpenID for a banking application, I feel it is a nice fit for my home project, it is used by local recruiters to post job postings. Up to this point every account holder had to provide her own username (email) and a password.

None of the information stored by jRecruiter is extremely sensitive and thus, OpenID might actually help improve the user experience of people posting jobs through the system. Over the past few years I saw a common issue that account holder are unable to remember their password, or even their username (which made me to change over to more of a email-based username approach). Ultimately, there were quite a few duplicate registrations in the past.

An interesting question though is, is it advisable to restrict access to a limited amount of OpenID providers? (Such as myOpenID, Google or Yahoo)

Use Case

Well, this is were things are getting interesting, OpenID does not only define the notion of pure authentication but it can also gives you access to various pieces of your OpenID profile (e.g. first name, last name, email address etc.). This feature seems to vary, though, between providers (Have to see how that works out)

Thus, for jRecruiter I envision the following use case. When a user starts the login process:

she or he has a choice of either loggin in the traditional way using a username/password combination or
by selecting the OpenID route.
If the user logs in via OpenID and the authentication succeeds, but the user account within jRecruiter does not exists, yet, then the potential user is redirected to the registration pages and the fields of the registration form shall be pre-populated (as much as possible) using inforamtion from the user's OpenID profile.

In my next blog installment I would like to give you some insights of how I created a first draft implementation using Spring Security 3.0. Keep in mind that this is an ongoing (learning) process...Thus, if you see issues, let me know.

Continue with part 2.

Warbler and JRuby on Netbeans

2009-12-08T08:35:00.001-05:00

Have been brushing up my Rails skills last night. I installed the latest Netbeans version (NetBeans IDE 6.8 Release Candidate 2)

Everything looked great but during project setup, I selected the option to use Warbler ('Add Rake Targets to Support App Server Deployment (.war)'). As it turns out, setting up Warbler during project setup just 'breaks'. I have been using the "Built-in JRuby 1.4.0". It seems to be a path issue on my Mac running Snow Leopard (there were some indications on the web).

Ultimately, I was able to solve that issue by installing a dedicated JRuby version that had a nice shorter path.

Before:

"/Applications/NetBeans/NetBeans 6.8 RC2.app/Contents/Resources/NetBeans/ruby2/jruby-1.4.0/bin/jruby" -S gem unpack warbler
rake aborted!
Command failed with status (127): ["/Applications/NetBeans/NetBeans 6.8 RC2.a...]
/Applications/NetBeans/NetBeans 6.8 RC2.app/Contents/Resources/NetBeans/ruby2/jruby-1.4.0/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:995:in `sh'
(See full trace by running task with --trace)

After:

/Users/hillert/_APPS/jruby-1.4.0/bin/jruby -S gem unpack warbler

Unpacked gem: '/Users/hillert/NetBeansProjects/DX2010/vendor/plugins/warbler-0.9.14'

I haven been running into a few other issues to finally get a simple Rails deployment working on my Tomcat instance, but that is a new blog post to come...

Great Time at the Scala Meeting

2009-12-04T00:00:00.002-05:00

I had a great time at the Scala meeting here in Atlanta, tonight. This was the first time for the Scala group to meet in a central location (Same place as the AJUG meetings) and the group was able to double their attendance to almost 20 attendees.

For me it was also very nice to meet Lex Spoon, co-author of 'the book' on Scala 'Programming in Scala'. Also, this is a small world - As a Java Posse fan, it was interesting to realize that John Weathers, the organizer for the Scala Meetup Group and Dick Wall worked together in Atlanta. Besides being a big advocate for Java, Dick is also very involved with the Scala scene in the Bay Area.

Anyway, seeing the potential of Scala combined with the talent we are having here in Atlanta, there is a great bright future for the Scala community, and with it the larger JVM community. These are exciting times!

Scala Meetup in Atlanta (3 Dec 2009)

2009-11-25T00:01:00.000-05:00

Just updated the AJUG website. recognizing that various JVM languages are gaining popularity, we will be starting to sponsor the Atlanta Scala Meetup (With meeting space). The next meeting is on December 3rd, 2009 at the usual AJUG location (Holiday Inn Select)

For more details, please visit: http://www.ajug.org/ and http://www.meetup.com/atlanta-scala/.

¡Viva La JVM!

Oracle, Flex and MOS - a sign for Java FX?

2009-11-20T08:30:00.040-05:00

Ok, while we are still waiting for the Oracla/Sun purchase to go through, there is also lots of speculating about what might happen with Sun's technology portfolio moving forward.

Since the world is moving towards richer UI interfaces for the browser, I am always in the struggle to assess which technology stacks are most appropriate to learn (GWT, Flex, plain HTML + your choice of JavaScript library such as JQuery, YUI etc.). Thus, particularly as a Java developer I am of course interested in the outlook of JavaFX - I certainly "wish" it be successful, but it still seems to be lacking in various areas (Component libraries, JVM modularization, 'community'). Furthermore, there has not been any Oracles/Sun statements about the future of JavaFX as far as I know (Please comment if I am wrong)

There was a higher-level article in InfoWorld yesterday discussing the future of Sun's technologies:
http://www.infoworld.com/d/developer-world/java-what-does-its-future-hold-978

Oracles involvmen into Flex

This brings me to the main trigger point that caused me to this blog entry. A few days back, I read a news article at Heise Online, a large German IT news portal, stating that Oracle has some major issues while switching over to their new support system 'My Oracle Support' (MOS):

http://www.heise.de/ix/meldung/Oracles-neues-Support-Portal-aergert-Kunden-856450.html

You can read more the issues here:

The more interesting fact, though, is that their entire new support system is implemented in Adobe Flex. Unfortunately, I was unable to find more technical details via Google, but that is a fairly substantial deployment.

I found another interesting little piece of information on stackoverflow:

http://stackoverflow.com/questions/1601444/flex-oracle-open-world-2009

According to James Ward (Flex evangelist at Adobe), Oracle showed more Flex-based applications this year at Oracle OpenWorld 2009 including: My Oracle Support, Social CRM, Siebel Gadgets and Enterprise Manager.

Can you draw any conclusions out of this regarding the future of JavaFX? Probably (hopefully) not, but it shows that Oracle has already made a significant investment into Adobe Flex.

Adobe Flex and JavaFX in Atlanta

To give you some idea of how the market looks like here in Atlanta, Ga:

At the last meeting of the Atlanta Java Users Group (November 2009), Burr Sutter our group's president asked the group (80+ attendees) whether they use Adobe Flex and a considerable amount of hands went up (I guess at least 1/3). Nobody in the rooms did anything with JavaFX...

* * * *

PS: On a more frustrating side-note: While writing this blog post I visited http://www.javafx.com/ and my browsers froze (FF on Mac), causing me to re-type a good portion of my blog entry (Sigh).

Geeking out with Adobe Flex

2009-11-08T23:13:00.001-05:00

Just some quick notes...I had some extra time this weekend and watched several excellent online presentations mostly about Adobe Flex. Adobe is doing a really good job of making their conference presentations freely available.

I worked my way through the following Adobe Max 2009 presentations:

Also, in the past I must have seriously overlooked Adobe TV. Seems to be a pretty neat educational resource. There I watched: Using the Flex Charting Components

Lastly, I ended the weekend by watching Data Visualization and Dashboards by Thomas Gonzales (from 360|Flex Conference). By the way you should also seriously check out his blog: http://www.twgonzalez.com/blog/. There is some good stuff there.

In his presentation, Thomas showed some need examples. This one causes some serious drooling: http://www.brightpointinc.com/flexdemos/googlefinance.html

And just in case you need a gauge on your dashboards: http://www.twgonzalez.com/blog/?p=34 Oh, yeah.

Rich Charting Options for your RIA/Webapps

2009-11-07T22:30:00.038-05:00

I started revisiting my charting solution in jRecruiter. For this fairly basic Java web application, I have been using JFreeChart to provide basic charts (E.g. to illustrate the number of posted jobs over time).

While JFreeChart works great, and it pretty much provides all the charting features you may ever want, it has one disadvantage: It is static. Compared to all the interactive goodness that is possible with RIAs such as Flex, JFreeChart lacks the sugary icing on the top (Mouse overs, AJAX interaction, dynamic drill-down etc.). Therefore, I was investigating my options to add some richness.

Additionally, at work, I am using Google Web Toolkit (GWT) and thus wanted to get an overview about the charting capabilities I have using GWT. One of the options there is gchart. It looks okay, alas not great. What's worse, the project owner abandoned his project; see: http://code.google.com/p/gchart/.

Another option is flot which comes along as a jQuery plugin and uses the HTML canvas tag to do charting. There is a also a GWT wrapper for flot available called gflot.

The most interesting alternative for GWT, I came across is ofcgwt. It uses Open Flash Chart 2 under the hood and looks pretty good. You could argue that if you use Flash-based charting for your GWT app, why not just implement the entire app in Flex ;-).

On the pure Flash/Flex side, there are first of all the charting components that come with Flexbuilder. In contrast to the open-sourced Flex SDK, the charting components are not free, though.

While, I was googling for some other options, I saw Axiis - Simply beautiful! Yet, another option is IBM ILOG Elixir, which is free for free sites. They have a very nice compilation of examples: http://www.ilog.com/products/ilogelixir/demos/.

On a low level, you also may want to look at Degrafa (Even if it is just for the gorgeous examples). You can find one interesting charting example at this blog: Nike+ graph using Degrafa/Flex 3.

Lastly, if you don't mind spending some money, you may also look at FusionCharts. At one of my prior engagements we used used in very successfully in a Struts2-based web application. Fusion Charts also comes along in a flavor for Flex - see the samples. There is also a Google Code hosted GWT wrapper available.

This, concludes my little 30k-feet overview/list of 'Rich' charting options. If I missed a good one, please leave a comment!

NFJS Conference Atlanta 2010 - Day 3

2009-10-25T23:40:00.000-04:00

The last day is over. It's been a great conference. Without a doubt, JVM language alternatives dominated the conference sessions. Since I won a book on Scala yesterday, I will checkout that language out next :-)

Today, I attended two sessions by Ken Sipe: "Architecture and Scaling" and "So you want to be an Architect". I particularly enjoyed the latter one, as Ken gave a very pragmatic overview of his view on what the qualifications of an architect ought to be. I had to smile when somebody from the audience asked Ken how as an architect you can possibly keep up with the constant technical innovations and the sheer breath of required knowledge and Ken responded that he doesn't watch any TV. Well, I catch myself weekly listening to the Java Posse, SE Engineering Radio, Parleys.com etc. while doing the dishes, cleaning up etc. And with planning for AJUG meetings, the next Devnexus conference etc. there is not much time left for TV either (Although I still leave some space for my weekly dose of Southpark ;-)

I guess you really have to like what you're doing in order to fulfill the requirements of an Architect.

During the Birds of Feather (BOF) session I asked the panelists on their opinion about Python, which was never even mentioned at the conference but which at the same time is heavily used in computer science teaching at colleges in Georgia. Their opinion was, that it's white-space issue is just too much of a limiting factor for using it in HTML scripting, using it as a DSL etc. and also that there are some issues with the user community itself. And thus, they said, there were just better alternatives at this point.

During the afternoon I attended 2 sessions by Ted Neward

The Busy Java Developer's Guide to Advanced Collections
The Busy Java Developer's Guide to Hacking with the JDK

Both sessions were interesting but I wish Ted had given some more real world examples for use cases of Apache Commons Collections and the Google Collections Library. In his latter talk he showed an example of how to add functionality to core JVM classes. Interesting, but talking about "experimental and highly hacky stuff".

Overall, this was an absolutely wonderful conference. Looking forward to the next one! As always: Jay keep up the good work!

Don't use Java for New Projects - NFJS Day 2

2009-10-24T23:59:00.029-04:00

Day 2 of the No Fluff Just Stuff (NFJS) conference here in Atlanta is over - It's been a good day. It has been another day of excellent speakers and topics. One thread you can see clearly throughout the presentations is:

Java's days are numbered as a language for new development - Viva la JVM!!

I got the sense that you should at least start thinking about an exit strategy. Stuart Halloway was even more outspoken: "Don't use Java for new greenfield development." (Saying that any of the talked about alternatives are better - Scala, Clojure, Ruby and Groovy).

After going to a few sessions that dealt with concurrency, I am certainly not inclined (border-lined scared) to do that kind of stuff in Java. The two languages most talked about at the conference were Scala and Clojure.

The nice thing is, that both language run on the JVM, so you can use the new language features, but are also able to use the vast power of Java libraries, if needed. Once drawback I saw is the fact that both Scala and Clojure can be fairly cryptic, which was an issue that was raised repeatatly by the audience and as well during conversations with fellow developers in between session breaks. Scala at least gives you the ability to write Java like code and then later on as you gain proficiency, you can make your code more concise . From a "power perspective", Scala looks awesome, though.

The sessions I atended to today were:

Tackling Concurrency on the JVM (Venkat Venkat Subramaniam)
Advanced Topics in JMS (Mark Richards)
Java.next: Clojure, Groovy, JRuby, and Scala (Stuart Halloway)
What's New in Spring 3 (Ken Sipe)

Onto the last day now...

NFJS Conference Atlanta 2010 - Day 1

2009-10-24T01:08:00.002-04:00

Today was the first day of the NFJS conference here in Atlanta. It's my third time and it is always a great experience in terms of sessions but it is also a good opportunity to network.

First I went to two sessions of Venkat Subramaniam: "Effective Java" and "Programming Scala", both excellent sessions. I get the feeling, it is really time to look beyond Java, particularly if you do anything around concurrency. Not sure if Scala will be it, there seemed to be some contention in the crowd regarding Scala's more cryptic syntax. Although, it looked manageable in my opinion. Nevertheless, I need to check out the Clojure talk tomorrow.

The third session I attended was "Transaction Pitfalls and Strategies" by Mark Richards. At first I was a bit hesitant attending the session but I was glad I did. A related article can be found at IBM DeveloperWorks. The presentation contained some really good stuff.

The first day ended with a very good keynote by Ted Neward on Iconoclasm. Oh well, it is 1am already...better get some sleep for day two of the conference.

How to Teach CS to Children

2009-10-23T22:05:00.003-04:00

At the Atlanta Java Users Group (AJUG) we had an awesome presentation by Barbara Ericson on how to inspire children to learn more about computer science (CS). It was a really informative session. As director of Computing Outreach at Georgia Tech University she helps prepare curricular materials for high schools.

As such, she gave us a detailed overview of the state of CS teaching in Georgia and the nation as a whole. Furthermore, she gave us an overview of all the cool software tools that help teach CS concepts including:

She also talked about some interesting robotic toys that help in her efforts:

I wish I had had the stuff when I grew up...

There is even a website out there that provides free information on activities that teach CS concepts without a computer: http://csunplugged.org/

Lastly, if you have children of your own, you should certainly check out Barbara Ericson's presentation and you can also find many more resources on her website: http://coweb.cc.gatech.edu/ice-gt

Apache Camel Alternatives

2009-10-17T22:25:00.003-04:00

In part one of my mini series I provided a quick introduction to Apache Camel and in part two, I continued with a simple example illustrating the very basics to get you started (which I extended a bit in part three)

In this posting, I would like to talk about some of the alternatives that I see might be interesting for you to investigate, when considering an open-source enterprise integration framework. Hereby however, things always get a bit fuzzy in my opinion, depending on your business requirements.

On one side, you want to have components which allow you to communicate with other services, but on the other side you also want to have some sort of workflow-capabilities in order to orchestrate your business processes. Furthermore, you may be interested in monitoring and reporting functionality. From a different view-angle, you may desire a higher-level solution versus a solution that embeds easily into existing code using plain Java APIs. The list could probably be expanded considerably, but I hope you get the picture.

Ergo, depending on your specific business requirements, the following list of frameworks may or may not provide a better choice compared to Apache Camel:

Spring Integration
Spring Batch
JBPM
nexusBPM
Drools
Hadoop/Cascading
Full ESBs such as Service Mix, Mule ESB, OpenESB, JBossESB

Actually, in my opinion the closest alternative to Apache Camel is Spring Integration.

Spring Integration

Before I was even aware of Apache Camel, I learned about Spring Integration at the No Fluff Just Stuff (NFJS) Java conference one year ago. Back then I thought that Spring Integration was the best thing since Nutella. Then a little later I learned about Apache Camel and tried to figure which one to take for a spin. As it turns out, comparative information on Google is rather sparse:

Matt Raible has some interesting tidbits in one of his blog entries
There are some comments by Mark Fischer on the Spring Blog

Interestingly, Apache Camel provides a component that allows you to integrate Apache Camel with Spring Integration.

To me a good argument for Apache Camel was the greater availability of components compared to Spring Integration, as well as its adoption by other frameworks such as ActiveMQ and ServiceMix.

Spring Batch

If your business requirement is to process large amounts of data, you may also want to look at Spring Batch which is specifically designed for batch processing requirements. There are some pointers on the Spring Batch website for integrating it with Spring Integration. I considered it for one of my past projects, but unfortunately I do not have massively deep experience with it as we ultimately chose JBoss jBPM.

jBPM

In my opinion another option worth considering is jBPM from JBoss. I used it in one of my past projects. Integrating it back then with Spring was certainly a bit tricky (especially asynchronous execution of Nodes), but it is doable. Interestingly, starting with version 4.0, JBPM provides native Spring integration. Unfortunately, I did not have any opportunity, yet, to try out JBPM 4.0. JBPM is certainly much heavier compared to Apache Camel or Spring Integration. I would say that its focus is also slightly a different one. While it provides support for human task management during workflow executions, managing the state of your workflow nodes etc., it totally looses out compared to the available components, which are provided by Apache Camel.

nexusBPM

A little bit jBPM on steroids is nexusBPM (An older blog post of mine about it is here). Developed by Intercontinental Hotels Group here in Atlanta, it is open-sourced at Sourceforge and provides a set of useful components in addition to the original JBpm distribution.

Drools

You probably would not necessarily think of Drools being a Workflow solution but what originally started out as a rules engine seems to venture increasingly into other areas as well. In fact, at least from a 30k foot view, it pretty much provides similar functionality as JBPM (Workflow, human task management etc.) and also provides a few components such as FTP, mail, executing system commands, etc.

What kind of baffles me is the fact that JBoss is maintaining 2 very similar products...

Cascading and Hadoop

If you need to process large amounts of file-based data, then Cascading might also be an interesting alternative. Cascading uses MapReduce to handle chunks of data. Interestingly, you can also use it for creating workflows. Not too long ago I attended an interesting presentation on that subject at AJUG. The presentation can be found here.

ESB like ServiceMix, Mule, OpenESB

Last in my list of alternative frameworks to Apache Camel is an entire category of solutions: Enterprise Service Buses (ESB). Enterprise Service Buses are basically stand-alone products, and as such, have a much heavier foot-print than for example Apache Camel which is basically just a set of light-weight Java APIs. In fact Apache Service Mix 4.0 is using Apache Camel under the hood in order to provide message routing. Besides Apache ServiceMix, you may also look into these OSS products:

This concludes my VERY high-level overview of frameworks/products that allow you to implement worklow and/or enterprise integration-based solutions. This whole subject could easily be extended into a more comprehensive article. Nevertheless, I hope I was able (within the limits of a blog post) to provide you with some good starting points.

¡Hasta la próxima!

Camellos III - Zipping Files with Apache Camel Example

2009-10-04T12:04:00.001-04:00

I played a bit more with Apache Camel and I extended my little Camellos project (See this blogpost for details, including for directions to get to the source code) by another simple Example:

poll directory zip-input for any type of files
pack the files using the Zip data format
output files to the zip-output directory

I thought this would be an easy example to get my feet a bit more wet with Camel. Apache Camel provides 2 data formats for zipping files:

Interestingly, using the marshaller for the Zip data format, you're unable to generate standard zip file. Looking through the source code of the Zip daa format, it turns out that Apache Camel is using a DeflaterOutputStream to created the compressed data versus using a ZipOutputStream. A bug??

Thus, what a great opportunity to create my fist customized Camel Data Format implementation :-) I basically just took the existing ZipDataFormat class and converted it to using a ZipOutputstream, and by adding a single ZipEntry for my file. This works quite well.

I also added a reverse route for unzipping a file. One limitation exists. The zipfile can contain only one file. I am not sure, yet, how to solve the issue when you have more than one file in your zip file...I guess this may be a task for the Splitter or Aggregator components.

Proxying large Amounts of Data using UrlRewriteFilter

2009-09-26T00:09:00.000-04:00

Finally, I found some time to submit a feature request with patch to the UrlRewriteFilter project.

http://code.google.com/p/urlrewritefilter/issues/detail?id=53

In one of my projects we needed to provide functionality to post (upload) and download data via a servlet container to/from another url/port - basically we needed to implement proxying.

A great library out there is UrlRewriteFilter, a Java library that provides Apache's mod_rewrite functionality. Not only can you use it to make complex urls more user-fiendly, or re-map old url to new ones but it also provides proxying capabilities.

UrlRewriteFilter uses Apache HttpClient for doing proxying. Unfortunately, I ran into memory issues when proxying large amounts of data. The issue is that the current version of UrlRewriteFilter (3.2) is doing buffered requests while proxying. This probably works fine for 90% of all use-cases but for the project I am working on we need to basically support unlimited amounts of data to be proxied (multiple 100s of MB).

Thus I provided a patch, that worked really well in my project without increasing memory consumption.
In Apache HttpClient you can implement a custom class using the RequestEntity interface that allows you to stream the data directly.

Camellos - Discovering Apache Camel II

2009-09-24T08:00:00.001-04:00

As indicated in my last blog post, here is an example implementing a small Apache Camel example.

You can pick up the source code from:

Steps to get it running:

Check out the source
Using Maven run: mvn camel:run
The Application should compile and start up correctly.
You can now drop files into the camellos/inbox directory
The files should get uploaded to its the FTP server running at localhost:3333
The uploaded files should show up under camellos/ftp

Back to y example, for my little blog post example here I want to provide the following very simplistic functionality:

pick up files from an directory
make sure that you pick up no more than 3 files per 30 seconds
store them into a JMS queue
have a listener on that queue that picks up those files
and upload files to a remote FTP site

What do you think, how many lines of Java code does it take?

With Apache Camel you can get this simple task done with ZERO lines of Java code. Well, I needed 1 Main class with a few lines of code to load the Spring context and and the embedded FTP server. Nevertheless, I think that is quite impressive. In a sense all the heavy lifting is done in the Spring Application Context file:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:camel="http://camel.apache.org/schema/spring"
xmlns:ftpserver="http://mina.apache.org/ftpserver/spring/v1"
xmlns:amq="http://activemq.apache.org/schema/core"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd
http://mina.apache.org/ftpserver/spring/v1 http://mina.apache.org/ftpserver/ftpserver-1.0.xsd
http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">

<amq:broker useJmx="false" persistent="false">
<amq:transportConnectors>
<amq:transportConnector uri="tcp://localhost:0" />
</amq:transportConnectors>
</amq:broker>

<bean id="activemq" class="org.apache.activemq.camel.component.ActiveMQComponent">
<property name="brokerURL" value="vm://localhost"/>
</bean>

<ftpserver:server id="ftpServer" max-logins="10"
anon-enabled="true" max-anon-logins="5" max-login-failures="3"
login-failure-delay="20">
<ftpserver:listeners>
<ftpserver:nio-listener name="default" port="3333" local-address="localhost"/>
</ftpserver:listeners>
<ftpserver:file-user-manager file="users.properties" encrypt-passwords="clear" />
</ftpserver:server>

<camel:camelContext shouldStartContext="true" trace="true">
<camel:package>com.hillert.camellos</camel:package>
<camel:route id="route1">
<camel:from uri="file:camellos/inbox?move=.done" />
<camel:throttle maximumRequestsPerPeriod="1" timePeriodMillis="10000" >
<camel:to uri="activemq:queue:camellos"/>
</camel:throttle>
</camel:route>
<camel:route id="route2">
<camel:from uri="activemq:queue:camellos" />
<camel:to uri="ftp://admin@localhost:3333?password=secret"/>\
</camel:route>
</camel:camelContext>
</beans>

Apache Camel provides its own Maven plugin: http://camel.apache.org/camel-maven-plugin.html

Getting started with Apache Camel is simple. I recommend using m2Eclipse which is a Maven plugin for Eclipse. Basically Camel provides it's own Maven archetype which after running creates a simple project structure and which can be immediately run using mvn camel:run after project creation.

For my implementation I followed Camel's tutorial for creating a Spring based Camel route.
As my example uses a few more components for Apache Camel but also ActiveMQ for JMS and Apache Mina FTP Server, I needed some additional Maven dependencies.

Getting all the Maven dependencies right took actually longer than implementing the actual application logic. Anyway, I hope this gives you a quick overview of some basic Apache Camel features. As time permits I will blog about more about it soon. See you then!

PS: Apache Mina FtpServer, is itself a nice little nifty package. So if you for example have the need to boot-up dynamically FTP servers from within your application...check it out.

Camellos - Discovering Apache Camel I

2009-09-23T22:10:00.001-04:00

Over the next couple of weeks or months (depending how much spare-time I am able to allocate), I will dive into the world of Apache Camel (Also take a look at my second blog post)

Apache Camel is somewhat like a Swiss-army knife. As an integration framework (Message Routing API, Mediation Router), it implements all the Enterprise Integration Patterns from the book with the same name.

Next, Apache Camel provides a quite extensive component library supporting an impressive amount of communication protocols. Also, it support an wide range of data formats as well as integration points in terms of other frameworks such as Spring, Guice, ServiceMix, ActiveMQ et cetera.

Well, that's all nice and dandy—However, what does this mean for me as a software developer?

When you develop typical Java enterprise applications, you will sooner or later come across the requirement to connect to other systems or to add other asynchronous services to your applications. Something like:

"Hey, we need to pick up this file that comes in every night, parse it, process it and then stuff its data into our database and, while we're at it, also make sure the original file is archived somewhere in the file system."

Or maybe you just have some requirements where your application needs to send data to another server but you have to make sure, that the flow of data is "throttled" in order not to overburden your destination server during peak-processing times.

In all those cases Apache Camel can greatly simplify the implementation effort. It is basically a mini ESB in the form of a simple Java API. But it is extremely modular so you can just bits and pieces from it. In my next blog post I will show you an example showing you how it is really dead simple to get started with Apache Camel.

See second Camel related blog post.

GWT - Hosted Mode Gotcha in Windows

2009-09-19T22:00:00.000-04:00

I ran into a small gotcha while running a GWT application I am working on in hosted mode. Usually I am developing my application in hosted mode but for quick stand-alone deployments I also need to deploy the application to a dedicated servlet-container. Since the default settings cause the application to compile rather slowly, I have been trying to speed up GWT compilation times (Using GWT 1.7) by compiling against Firefox only (My browser of choice).

To achieve this I set the following property in my GWT module's *.gwt.xml file:

Well, as it turns out, this caused me quite some pain in hosted mode. I did not realize that the aforementioned setting affects hosted mode. I new that under Windows Internet Explorer (IE) is the default browser but always assumed it only affects fully compiled GWT code - not code running in hosted mode. That was a painful lesson - It caused some rather obscure errors in hosted mode and nowhere were I able to find explicit information regarding this issue.

jRecruiter is deployed and live

2009-08-30T22:30:00.000-04:00

Finally...it took ways to long. Last Sunday I finally made a new production deployment (Version 2.0) of jRecruiter). jRecruiter is the job posting service of the Atlanta Java Users Group (AJUG). This version was a long time in the making. I hope that from now on I can make new feature deployments more swiftly. The new version is accessible at: http://www.ajug.org/jrecruiter/

Here is a list of changes:

(Almost) No more Struts XML-configuration files. jRecruiter uses the Struts 2.1 convention plugin for annotation based configuration.
Many Spring Beans dependencies are now configured using annotations (Spring 3.0)
Sophisticated data-grid support using jMesa
Google Maps integration (web (Javascript), Pdf (Image) and Flex (Flash))
Hibernate Search support
RSS feeds for the latest 20 jobs using ROME
Social bookmarks on the job posting list
Application is now Struts 2.1 based
Using jasypt for password digesting
Administrative pages are SSL encrypted
Improved charting (JFreeCharts)
Using reCAPTCHA for the registration page
Implemented email account verification
Now job postings and updates are send to Twitter (http://twitter.com/ajug_jobs/)
PDF Export of Job Posting Details (using iText)
Switched from username-based logins to an email-based system (usernames are still supported on the backend (e.g. administrative logins)
Some performance improvements --> CSS and JavaScript files are now merged, minified and GZipped using JAWR)
XML web services for providing job posting data to Indeed.com (Still need to do the actual integration but the XML feed is there)
Using jQuery for most Javascript needs
Maven project consists of multiple modules now (web, server, flex)
I18N: Added partial support for German
Extra bonus: Added a simple Adobe Flex front-end using Spring Blaze DS for server integration

Integrate Twitter and bit.ly into your Java App

2009-07-29T02:15:00.004-04:00

I am in the final stage of developing towards the 2.0 release of jRecruiter. It is the job posting service of the Atlanta Java Users Group (AJUG) and as such I devote some of my spare-time towards it. It is a great way to explore all kinds of different technologies. Thus, last weekend I had the idea that it might be a cool idea to let the system "tweet" about job posting additions and updates. Here are my findings.

First I looked at available Twitter libraries for Java:

After some considerations, I chose Twitter4J. To me, it seemed to be the most active of the three projects. Even better, it has a BSD-style license. Using Twitter4J is super simple:


 Twitter twitter = new Twitter("username", "password");

 try {
     twitter.updateStatus("My tweet");
 } catch (TwitterException e) {
     …
 }

There is so much more you can with Twitter4J. Check out its documentation for further details.

Secondly, as each tweet contains a link back to the job detail page in the main application, I was looking into ways to shorten URLs. That way, I can store more job posting related data within the only 140 characters available for each Twitter status update.

The original service for this is TinyURL. However, it looks like bit.ly has more traction these days and is also used directly by Twitter itself. The nice thing about bit.ly is that they have developer accounts and are offering a web service API for doing URL shortening.

Even better, there is already a Java library available for using bit.ly called bitlyj. Using bitlyj is actually almost as equally simple to use as Twitter4j:


final Bitly bitly =
    BitlyFactory.newInstance("username", "your_bitly_api_key");
try {
    BitlyUrl bUrl = bitly.shorten("http://www.google.com/");
    URL url = bUrl.getShortUrl();
} catch (IOException e) {
    …
}

Unfortunately, you have to build bitlyj yourself, but thanks to Maven it is a piece of cake. One thing I noticed, is that the error handling of the library could be more robust. Accidentally, I was using my bit.ly password, initially. However, bit.ly provides an API Key. By the way if you ever wonder where you can get that API Key-It is right in your account page. Anyway, the library needs some attention but for my simple use-case it worked fine.

MapReduce, Hadoop and Cascading at AJUG

2009-07-23T00:23:00.003-04:00

Yesderday Chris Curtin, CTO at Silverpop, gave an awesome presentation on MapReduce, Hadoop and Cascading. I really enjoyed his wealth of real-world practical examples.

His presentation is available at: http://www.slideshare.net/chriscurtin
Thanks to John Willis, there is also a video recording available at: http://www.johnmwillis.com/ec2/hadoop-and-cascading-ajug-072109/

Book Review: Spring Web Flow 2 Web Development

2009-06-07T14:15:00.002-04:00

Spring Web Flow 2 Web Development by Sven Lüppken and Markus Stäuble is the currently only available book on Spring Web Flow 2.0. The book covers all the components that are part of the Spring Web Flow distribution such as:

Spring Web Flow
Spring Faces
Spring JavaScript

Additionally, the book also provides an overview of Spring Security. The book comes with example code for many of the chapters.

The provided examples, however, could have been a little more consistent. The main source example in this book is covered in chapter 5 (A simple bug tracker). I liked the given example, as it does not require a database. This makes it easy to understand the Spring Web Flow specific problem domain. However, considering the fact that the authors also talk about Spring Security in other chapters, it would have been nice, if they had used the bug tracker example throughout the book in order to create a “complete” application, that ties together Spring Web Flow, the persistence layer and Spring Security. Unfortunately, the code examples given in later chapters don't refer back to the bug tracker example. Instead, chapter 6, for example, uses a shopping cart example.

A further minor annoyance is that the source code for 2 of the chapters still contain the eclipse project files used by the authors. This may be confusing for some users as these project files still point to Microsoft SQL Server drivers on a windows D: drive. I, for instance, use a Mac...

In chapter 2 the book discusses on 4 pages Ant and Maven. I think it might have been simpler for the understanding of the book and the provided source code, if only one build system was used, e.g. Maven. Some of the code examples provide Ant and Maven build scripts but some other ones provide support for Maven, only.

Another anomaly was, that the book describes the installation of the Spring IDE plugins for Netbeans and Eclipse on 7 pages but then the authors mention in passing only that they are using Microsoft SQL Server as underlying persistence store for their example. As many Java developers may not have a MS SQL Server license, it may have been better to use open-source Databases such as MySQL or PostgreSQL.

The example in Chapter 3 uses HSQLDB for its database but earlier (Chapter 2) the authors use MS SQL Server. For consistency and simplicity reasons the book could have stuck with one database.

Chapter 4 deals with Spring Faces. The authors should have mentioned JBoss Seam, since Seam solves a similar problem as Spring Web Flow but having a default focus on JSF.

The book provides an entire chapter on JSF integration (Chapter 4). As JSF is a widely used framework and Spring Weblow provides native support for JSF. It would have been nice though, if support for other frameworks such as Struts 1 and 2 would have been illuminated.

As part of chapter 5, the book also provides information on Spring JavaScript. While it is part of the official Spring Web Flow distribution it is not necessarily essential for the working of Spring Web Flow and even its spec lead Keith Donald mentioned at the Atlanta Java Users Group (AJUG) meeting in November'08 that it maybe extracted into its own project in the future.

The section in chapter 5 which starts on page 165, the Web Flow Configuration, felt repetitive to parts of Chapter 3 (pages 53) and should have probably merged with that section. Chapter 5 also contains a larger section on Apache Tiles integration. One thing that I did not understand was how Tiles matters in terms of mastering Spring Web Flow. Generally I don't mind explaining additional pieces of information around the edges of your problem domain but if that happens on 5 percent of the book, it needs to matter within the context of the targeted subject. On a site-note: Take a look at SiteMesh for your templating needs. I strongly prefer it compared to Tiles.

In chapter 6 the testing of your Spring Web Flows is explained. This was an informative chapter and I particularly liked mentioning of EasyMock.

In chapter 7 the book primarily details Spring Security. In my opinion, it provides too much Spring Security centric information. For example, the chapter describes how to create and write your own AccessDecisionVoter. In my opinion it does not help and is unnecessary for the understanding of Spring Web Flow. At most I would have chosen an example that uses a DB-backed security implementation using default Spring Security functionality.

To me, chapter 7 was a bit strange. It provides 16 pages of information introducing Spring Security but the actual integration of Spring Web Flow with Spring Security is accomplished in merely 4 pages. Most interestingly, that's where the book simply ends. I missed something like a wrap-up, that summarizes what the book covered and where to continue on.

In Appendix B the authors provide an overview of Springsource's dm Server. Personally, I think that dm Server is an interesting offering. However, I don't understand why this appendix even exists in this book. It is neither important for the understanding of Spring Web Flow, nor do the authors explain why this appendix exists.

Here are some further thoughts: Throughout the book, I like the use of Maven for building the examples. It certainly makes it easy to understand the examples' structure.

I think for the understanding of Spring Web Flow, it unnecessarily complicates things, if you present examples that require JNDI for establishing database connectivity. Furthermore it binds you to a concrete application server, which in this case is Tomcat.

Except for a for a very brief mentioning on page 224, the book never talked about the applicability of Spring Web Flow in the context of RIA frameworks such as GWT, Flex etc. Is there a use case for Spring Web Flow e.g. for coarse grained server state for large, complex applications?

It would have been nice if the book provided an overview of other frameworks that handle conversational state such as JBoss Seam. Additionally, since the books was published in March 2009, it could have described some of the planned conversational state management support planned for Spring 3.0.

Furthermore, it would have been great if the book had also mentioned how Terracotta can be used to back Spring Web Flow conversations. Terracotta provides an interesting reference application detailing that possibility.

Anyway, the book follows generally the Spring Web Flow documentation. The question is how much more value does the book add compared to the reference documentation. Overall, I have a quite conflicted opinion about this book. I think, if you are interesting in JSF integration or the bulk of the additionally discussed technologies (E.g. Spring JavaScript), then this book may add enough information for you. It certainly provides some useful information regarding Spring Web Flow 2.0.

Unfortunately, it contains quite a few inconsistencies and it is overall not an easy read. However, it is the only currently available book dealing with Spring Webflow 2.0. On Amazon, I gave the book 2 out of 5 stars.

Book Review: Learning Flex 3

2009-06-03T03:00:00.002-04:00

Learning Flex 3 by Alaric Cole is a great introductory book for Adobe Flex 3. If you have some basic experience with HTML, JavaScript and CSS, then you will learn the basics of Flex rapidly using this book as a guide. Some of the areas that are taught are:

How to use Flexbuilder
Using MXML
ActionScript 3
Styling your application using CSS

However, if your professional background is in web-application development using Java or other OO languages, then you are probably more likely to skip or cross-read sections of the book. This is because the book starts out with practically no initial pre-requirements, and thus you might be familiar with some of the discussed areas.

The book gave me an excellent overview of Flex's capabilities, and they are all explained thoroughly and are easily understandable. Also, this may sound silly, but I particularly liked the refreshing fact that the book is in color, unlike most other IT books.

Furthermore, the book explained Data Binding (Chapter 7) very well. This is something I was not familiar with coming from the Java world. The chapter illustrates the concepts of one-way binding, two-way binding and making your own variables “bindable” using a metadata declaration, which is basically an annotation in Java parlance.

Another feature I liked a lot was View States (Chapter 12), which allows you to rearrange, group and reuse components within your application.

I wish the book provided more information for further reading. I understand that certain concepts are beyond the scope of this book, but it would have been nice if those had been mentioned and links or recommendations for further reading were provided.

For example, while AMF is mentioned on page 8 and on page 157 the book briefly talks about the Webservice and RemoteObject component, the book should have also mentioned BlazeDS as one of Flex's core technologies for communicating with back-end servers.

And for more complex applications, the book could have at least pointed out some of the available MVC frameworks for Flex and some pointers of where to read more about them (E.g. Cairngorm and PureMVC). Well, and then there is Degrafa, the declarative graphics framework…

While the author explains the aspects of using CSS in Flex applications very well, he could have further stressed that Flex uses a subset of CSS, which in certain areas behaves differently compared to CSS you more typically use in HTML pages. He should have enumerated some of those pitfalls.

Having said all this, these issues mentioned above are minor in nature. Overall, the book was a fun read! And particularly to Java web-developers, Flex may very well be THE contender for application user interfaces moving forward. One of the great things about Flex is that even the standard components look very good (and should be good enough to please your boss), and your application looks and behaves consistently across various browsers. Oh, and yes you can run the same application on the desktop as well (Chapter 15).

This book will definitely help you learn and master Flex, and you should be able to produce functional user interfaces quickly. In order to learn more about integrating Flex with your Spring powered back-end you may want to also consider looking at “Pro Flex on Spring”.

JavaRebel + m2eclipse = Sweet Spot

2009-05-14T09:45:00.000-04:00

One of the pain-points while developing Java-based web-applications is the issue of the bouncing server. Every time you change a class file, your web application context needs a restart. While this is mildly annoying for small applications, it is simply unbearable for anything more substantial.

As far as I now the best and cheapest solution so far has been to use MyEclipse. It worked great and I rarely had to restart web contexts.

I always wondered why the standard IDEs (E.g. plain Eclipse WTP, IntelliJ ) never solved that re-deployment issue. Well, at least I have not been able to get this sufficiently working in plain Eclipse+WTP or IDEA IntelliJ.

Unfortunately, with the advent of Maven, MyEclipse started to loose come of its charm. For years, they were not able to provide an acceptable Maven integration (There was an entry on their forum for years demanding that feature) and on the other side, WTP started to become usable (I have not really tested the Maven integration introduced with MyEclipse 7 but I have read, that it is still not perfect). But one thing, that MyEclipse had nonetheless going for it, were its hot deployment capabilities.

Enter ZeroTurnaround's JavaRebel. Four weeks ago I started looking at JavaRebel and have been using it for the development of my OSS project since then. My verdict: It is awesome.

I use it in conjunction with the m2eclipse plugin and it simply works. ZeroTurnaround provides guides regarding the Eclipse and Maven integration (here and here) that are fairly straigtforward. It also comes with support for Spring and Struts2 directly.

The nice thing about JavaRebel is that it is agnostic to the used IDE as it simply hooks into the JVM as a Java agent. Therefore, you probably could also easily use it from the command line (in case you like to code using VI :-).

One drawback is the price which makes JavaRebel more expensive than MyEclipse. On the other hand, there is not much in MyEclipse that you cannot have in plain Eclipse/WTP using free plugins. Thus, ultimately it may boil down to personal preference but to me JavaRebel with plain Eclipse WTP (or IntelliJ for that matter) is the much nicer package. And if you have a project with an OSS license you can get JavaRebel for free, and don't have to buy MyEclipse.

Vi on a fresh Ubuntu installation - issue

2009-05-08T00:56:00.002-04:00

I am in the process of setting up Ubuntu 9.04 on my Linode instance. Looks like Vi was behaving screwy (Keys did not work as expected). Luckily there is Google and the following link helped.

I created a .vimrc file in my home directory:

vi ~/.vimrc

and added the following line to it:

set nocompatible

That worked for me.

Postfix relay messages to different port

2009-04-28T00:55:00.002-04:00

A frequent occurrence in applications is to send out emails. In order to test that behavior sufficiently during development, I usually use one of two options. On Windows you can use Mailster (preferred) or you can use postfix etc. on Mac/Linux (Have not been able to get Mailster going on my Mac)

So far on my Mac until recently it was as easy as to simply do: sudo postfix start and I was good to go. Unfortunately, my domain hoster does not accept mail on port 25 anymore. And the simple relay stopped working.

As it turns out though, you can easily relay to a different port (My hoster accepts port 26):

sudo vi /etc/postfix/main.cf
I added a line (near # INTERNET OR INTRANET):

relayhost = myHost.com:26

And finally I reloaded my postfix configuration using sudo postfix reload and I was back in business once again.

Woes with Oracle's Jdbc Driver and BigDecimal

2009-04-01T02:25:00.001-04:00

As other people before me noticed, Oracle seems to have issues with BigDecimals. Well, I hit one of those issues today:

BigDecimal.valueOf(0.000000548) became 0.000000538 in the database
new BigDecimal("0.000000548") became 0.000000538 in the database
persisting a plain String "0.000000548" worked fine however
new BigDecimal("0.000000458") became 0.000000448 in the database

The table column, to which the values were saved, had plenty of "scale'n'precision".
The issue occurred in Oracle's JDBC driver version 10.2.0.1.0. Luckily, after upgrading the drivers to version 10.2.0.4.0 the problems went away.

This is by itself an amazing issue - Just imagine, you were running a larger financial app. You may not even notice this subtle issue until your app is long in production. Oh well...

DevNexus Report Part 2

2009-03-28T16:00:00.002-04:00

In part one I provided an overview of attended DevNexus sessions. Here are some more details I took away from the presentations. The first days of the conference started out with Neil Ford, who always seems to provide those excellent but more high-level-off-the-beaten-path-type presentations (The presentation certainly contained an interesting Angelina Jolie picture). In his presentation he talked mainly about a quality work environment and how to be more productive as a developer. In his opinion giving developers their own office would be the best as it allows them to fully concentrate on the given development tasks. If that is not feasible and you're not working for Joel, then an open room configuration is the next-best compromise. And finally the worst solution: cubicles. Those suckers simply slurp your brain dry…

Well, afterward I headed over to Ari Zilka's talk about Terracotta. He gave an overview/introduction of Terracotta's capabilities. The presentation was quite similar to the talk we had at our monthly AJUG meeting last year but since then Terracotta published a new reference web application (Examinator) that really looks sharp and consist of a very good technology stack besides the fact that it uses Terracotta:

Spring MVC
Spring Webflow
Spring Security
JPA (Hibernate)
FreeMarker
SiteMesh
MySQL

One example he gave that stuck with me quite well, was the typical email registration process, when signing up for a new user account. You provide an email address, but before the account can be activated, you need to verify the email address using a verification email. However, using Terracotta, you're able to defer saving the email to the database until verification is complete and thus you can keep "state" information out of the database.

Afterward, I listened to Charlie Hubbard's talk on GridGain. This was an interesting talk in that GridGain is tackling distributed computing from a different angle than Terracotta. You are basically using it to farm out little chunks of data that are then processed by those nodes. It feels very reminiscent to using JMS with Publish/Subscribe with some processing logic bolted on.

After this talk I attended Bill Burke's talk on REST. It is interesting how various frameworks converge to a common point these days - RestEasy looked like Spring MVC 3.0 :-)

The last talk I visited was on Jared's Richardson's talk on 'using agile to optimize' which was a good talk. It reminds me that I still need to read his book Ship It!

At the end of the day we all headed down to the bar and had a few drinks. I met a former colleque of mine and chatted a while with Charlie Hubbard and Lance Gleason. A long good day…

RIA, Flex and Excitement

2009-03-26T02:15:00.002-04:00

I cannot believe that already two weeks passed by since the Atlanta DevNexus conference. Since then I have been quite busy learning Flex. My desire to explore Flex started back when James Ward talked at one of our AJUG meetings several months ago. Unfortunately, beyond some initial explorations, I never found the time to make the next leap forward.

The presentations at the DevNexus conference, though, finally pushed me beyond that initial hump. At the conference I attended the talks for GWT, JavaFX and Flex. Here is what I took away from it:

No doubt, GWT looks great and I think it is in the process of capturing a good share of the pie among Java developers. Since you write the GUI using Java (Compiled into JavaScript), it is a really nice component-based Framework (forget JSF). The ability to unit test your GUI code with just jUnit is cool, too. Something I was not aware of prior to attending DevNexus is the ability to also embed GWT into existing applications (e.g. a DIV on a page). However, at the end of the day you're still creating HTML with its limitations in terms of richness.

In terms of that, JavaFX has potential in my opinion. While it comes with its own scripting language you are still able to use the the full breath of exisitng Java libraries. Unfortunately, JavaFX does not seem to be there, yet. While some of the example application look nice, it still lacks some important pieces, e.g. lots of standard components. At the end of the day, most developers are building business apps and thus need standard components for datagrids, charting etc.

This was also one of the key complaints Yakov Fain (See picture) made at his DevNexus presentation which gave the audience an overview of various RIA technologies. (Another perspective on the JavaFX was posted by Javalobby: Where in the world is JavaFX?)

And therefore, by the end of the conference I was mostly convinced that Adobe Flex is the best technology at the moment for delivering rich internet applications. Don't get me wrong, I still hope that JavaFX can make it and maybe IBM fancies with the idea of becoming a player in that area and provides some more resources once BlueSun is born.

Nevertheless, once the conference was over, I made the decision to take the Flex deep dive. I mostly finished reading Learning Flex 3 and I just started reading Pro Flex on Spring. For both books I am planning on publishing book reviews soon.

As an example I am in the process of creating a simple Flex-based front-end (highly experimental) for jRecruiter my open source project. So far I have setup the Spring BlazeDS 1.0M2 integration and I am pulling back job postings from the server using AMF and showing them in a data-grid component. Furthermore, I added Google Maps to the Flex application which works pretty neat. It gives you the ability to show job postings on a map (and thus helping you estimate possible morning commutes). I hope to have a deployed version available soon. In the meantime, here is an early screen-shot:

DevNexus Audio Files Available Now

2009-03-16T07:42:00.004-04:00

Originally we did not plan on recording the sessions during DevNexus 2009, but thanks to the help of Stephen Davis we are able to provide recordings of ten presentations. The quality could be better but I think the presenter is mostly intelligible. The recordings are available here.

DevNexus 2009 Report Part 1

2009-03-13T22:32:00.006-04:00

More than half a year of preparation finally culminated in the grande finale from March 10 to 11 at the DevNexus conference. The result was in my opinion a great success. We received many emails from speakers and attendees alike, commenting on the very good quality of the DevNexus conference. This was the biggest event that I helped organizing, yet. I already have a few ideas and areas of improvement for DevNexus 2010. But that is subject of a future blog post…

Overall, I truly enjoyed the speaker line-up. Here are the presentations I attended:

March 10

On the Lam from the Furniture Police by Neil Ford
Terracotta - Real Apps, Real Frameworks, Real Use Cases by Ari Zilka
Introduction to Grid based computing with GridGain by Charlie Hubbard
Scaling RESTful Services with JAX-RS by Bill Burke
Software Teams Tuneup: Using Agile to Optimize by Jared Richardson
Scaling Hibernate: tips, recipes and new perspectives by Emmanuel Bernard

March 11

JavaFX: The Platform for Rich Internet Applications by Doris Chen
Picking the right technology for the Rich Internet Application by Yakov Fain
GWT by Bruce Johnson
Developing Modular Web Applications with Spring 3.0 by Keith Donald
Automatic generation of Flex/Java CRUD applications by Yakov Fain

By the way the slides are available here.

I will try to provide some more details and impressions about the attended talks in the next few days. Stay tuned.

DevNexus 2009 Presentation Slides Available

2009-03-13T02:00:00.002-04:00

This evening I uploaded a whole bunch of presentations from DevNexus 2009, the Atlanta developer conference. The majority of the talks is now available at: http://www.devnexus.com/download.html

I hope that within the next couple of days, we will be able to make the remaining presentations available as well.

I18N your Java Web Application

2009-03-12T01:20:00.000-04:00

I went through the exercise of internationalizing (I18N) my home project. It is still work in progress but I added support for German in most places. Unfortunately, I got a bit bitten by the fact that by default properties files in Java have to be encoded in ISO-8859-1. Up to today, all web applications I helped developing, were created for an English speaking target audience, and therefore, even though they often used properties files, they never went beyond the standard character set.

Interestingly, though, if you like using typographically correct characters like the ellipsis or quotation marks, you would run into the same issue. For that reason alone I think everything (Your JSP files, server, database, source code etc. should all be able to handle UTF-8)

Nevertheless, the limitation that properties files by default are not cannot be in UTF-8 is quite annoying, as it would require you to escape special non-ISO-8859-1 characters or use a conversion tools such as native2ascii. This blog post summarizes the general issue nicely.

For my project I am using Struts 2.1. By default it does not allow for UTF-8 based message resources. Since Java 6 introduced support for creating a custom loader when accessing resource bundles, I was looking into ways of maybe extending Struts 2. Well, it looks like Struts 2 does neither allow a custom ResourceBundle Control nor for easy patching of Struts itself. See also: https://issues.apache.org/struts/browse/WW-2774

Nevertheless, even though Struts 2.1 improved substantially compared to Struts 2.0.x, I am still debating whether long-term Spring MVC (Especially Spring MVC 3.0) might represent a better choice—With Spring 2.5+ both web frameworks are certainly getting very similar. The nice thing about Spring (Core) is, that it provides the ReloadableResourceBundleMessageSource which provides exactly what was looking for:


<bean id="messageSource"
  class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
    <property name="basename" value="classpath:messages"/>
    <property name="defaultEncoding" value="utf-8"/>
</bean>

Unfortunately, as mentioned above, it looks like there is not an easy pluggable way of convincing Struts 2's textprovider to use Spring's messageSource implementation. As I am already using Spring MVC for some of my actions, I decided to use Spring's message tag within my JSPs, I am not crazy about it, as I now mix different web-frameworks but it seems to work like a charm right now.

Two last questions to answer are:

What is the best way to edit resource bundles using eclipse?
How do ou structure your resource bundles without loosing track of things?

After searching the web for a while, I finally settled for Eclipse Resource Bundle Editor. It works quite nicely, I just wish something useful like this would be built into Eclipse by default.

As for structuring the property files, I settled pretty much on a jsp-by-jsp structure. E.g. if I have a file edit-settings.jsp and I want to customize the page title, then I create a resource bundle entry jsp.edit-settings.title=My settings

Similarily I deal with class files:

class.AddUserAcion.success = The user has been successfully registered.

Just as additional information: I wonder, whether it might be a cool thing, to be able to structure properties files similar to Rails 2.2+. There is an interesting RailsCast available about how to do I18N in Ruby On Rails.

DevNexus is here—See you there!

2009-03-10T00:05:00.002-04:00

Over half a year in the making and the conference is finally here. The last preparations are done, the goody bags are stuffed (yesterday). Let's rock :-)

Hope to see you there tomorrow!

Information Resource regarding Climate Change

2009-03-08T21:28:00.002-04:00

While reading Thomas Friedman's latest column in the New York Times, he pointed out the blog of Joseph J. Romm, which you can find at http://climateprogress.org/. It is an interesting blog that summarizes the latest developments regarding climate change.

jQuery UI and ThemeRoller

2009-03-06T02:20:00.003-05:00

I use jQuery quite extensively in my projects these days, but I kind of ignored jQuery UI for too long. The last two days, though, I finally got more into jQuery UI, after I was looking for a modal dialog component and realized that jQuery UI provides a very nice implementation by itself.

I haven't done much directly with the available components (except the dialog component), but
I was very much impressed about the way you download jQuery UI. They call it "Build Your Download" which let's you pick and choose which components of jQuery UI you may want to use and it creates a customized download bundle for you.

But substantially more impressive is "ThemeRoller", which not only let's you select between various themes but also allows for editing and creating new themes. All changes are applied right on the spot and once you're done you can include the theme in your customized jQuery UI download.

From there I discovered that jQuery released a new CSS Framework called "jQuery UI CSS Framework". It looks quite promising and I wonder if it might be applicable for my pet project. I certainly need to learn more about it...it would be nice if it could serve as the main CSS for my web application and therefore allow for easy theming of the application.

Anyway the docs can be found at http://docs.jquery.com/UI/Theming/API and the wiki pages are located at http://jqueryui.pbwiki.com/jQuery-UI-CSS-Framework

There is also a themeswitcher component available.
http://docs.jquery.com/UI/Theming/ThemeSwitcher

Lastly there is an interesting article on the blog of filament group, one of the main sponsors of jQuery UI, about styling buttons and toobars.