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

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:

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

Onto the last day now...

NFJS Conference Atlanta 2010 - Day 1

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

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:

• Scratch
• Alice
• Media Computation
• Greenfoot

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

• PicoCrickets
• IPRE Robots
• Pleo Robots
• LEGO NXT robots

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

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:

• Mule ESB 
• OpenESB  
• JBossESB
• Apache Synapse (See: Comparison ServiceMix and Synapse)
  

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

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:

1. poll directory zip-input for any type of files
   
2. pack the files using the Zip data format
   
3. 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:

• GZip Data Format (Source Code)
• Zip Data Format (Source Code)

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

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

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:

• Checkout: http://jrecruiter.googlecode.com/svn/trunk/camellos/
• View: http://code.google.com/p/jrecruiter/source/browse/#svn/trunk/camellos

Steps to get it running:

1. Check out the source
2. Using Maven run: mvn camel:run
3. The Application should compile and start up correctly.
4. You can now drop files into the camellos/inbox directory
5. The files should get uploaded to its the FTP server running at localhost:3333
6. 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:

1. pick up files from an directory
2. make sure that you pick up no more than 3 files per 30 seconds
   
3. store them into a JMS queue
4. have a listener on that queue that picks up those files
5. 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

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

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

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