Tuesday, February 22, 2011

DevNexus 2011 - Craft Rich (Mobile) Internet Applications

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/

Monday, February 7, 2011

Spring Mobile M3 - Site Preference

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:
  1. Device Resolution
  2. Site Preference Management
  3. 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:


I updated my spring web context xml file:

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

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.