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Deploying GWT Applications in SpringSource dm Server - Part 2


This is the second in a series of three blogs describing a step-by-step approach to building and deploying GWT applications in the SpringSource dm Server™. The first blog looked at the process of creating a simple WAR file from a sample GWT application. This next blog will look at turning the WAR file we created in Part 1 into a “Shared Libraries” WAR. This means that we are going to externalize the GWT dependencies of our application into an OSGi bundle so that it can be shared by any number of GWT applications. You can think of it as extending our dm Server with GWT remoting capabilities.


Diagnosing OSGi uses conflicts

In his recent blog entry, Glyn provided an introduction to the OSGi “uses” directive. In this blog, I want to dig a little deeper into the causes of uses constraint violations and present some tips for diagnosing uses problems in your applications.

For most of the examples I’m going to be using raw Equinox and not dm Server. The reason for this is that uses constraints are not specific to dm Server but are relevant to all OSGi users. At the end of this blog, I’ll demonstrate some of the smart constraint failure diagnostics built into dm Server.


First Grails Release Under the SpringSource Banner

I’m pleased to announce the first release of Grails since the acquisition of G2One by SpringSource. Grails 1.0.4 includes a number of improvements as well as upgrades to key libraries that underpin Grails and can be downloaded from the Grails download page. More specifically Grails 1.0.4 ships with the latest Spring 2.5.6 release that came out a week or so ago.

Beyond the improvements there are a couple of interesting new features in this release. The first is the addition of a feature that better supports mapping of Hibernate user type definitions in GORM. You can now map custom user types onto multiple columns, including the ability to customize the underlying SQL type:


More Weapons for the War on Complexity: SpringSource Acquires Groovy/Grails Leader

I am delighted to announce that SpringSource has acquired G2One, the company behind Grails and Groovy.


Grails is a great fit with Spring and SpringSource technologies. Grails is built on Spring. It offers another route to adopt Spring, the de facto standard component model for enterprise Java. All the power of Spring (and Java) lies beneath the surface of every Grails based application—a key reason that Grails can scale to enterprise use, as well as a validation of Spring’s power and flexibility.


Deploying GWT Applications in SpringSource dm Server - Part 1


This will be a series of 3 blogs describing a step-by-step approach to building and deploying GWT applications in the SpringSource dm Server™. The focus of the blogs will be as follows:

  1. Building and deploying the GWT StockWatcher sample app as a WAR file in dm Server, using the SpringSource Tool Suite to build it from scratch.

  2. Deploying with a “Shared Libraries” approach: How to remove the GWT dependencies from the WAR and deploy them as an OSGi bundle in dm Server.

  3. Deploying with a “Shared Services” approach: We convert the single WAR file into OSGi services which can be shared by other applications and hot-swapped out.


A Word About the Election

No, not the Obama/McCain smackdown on Nov 4. As you may have read in SD Times, SpringSource has been elected to the JCP Executive Committee for Java SE/EE, along with SAP, Ericsson, Nokia, Philips, and IBM. I will be the SpringSource representative.

Not that the JCP matches the scale of the presidential race. But this is an important moment for SpringSource, and one that reflects the years of hard work and leadership the entire team at SpringSource has provided in enterprise Java. More importantly, I believe that our election will help us to make Java stronger.


Getting started with SpringSource dm Server

Updated 28-Oct-2008: Added up-to-date sample links and link to third sample

Last night I presented ‘Introduction to SpringSource dm Server’ at the Philadelphia Spring User’s Group. During this presentation I created a small application called GreenPages, demonstrating all the major aspects of dm Server. I promised the attendees that I would post the application and the slides here.

In the last few weeks since the GA release of dm Server many people have been asking about the best way to get started with dm Server, so I’m using this entry to collect all the relevant information together, including the Introduction to SpringSource dm Server presentation.


Spring Batch 2.0 New Feature Rundown

In this article we outline the main themes of Spring Batch 2.0, and highlight the changes from 1.x. Development work on the new release is well underway, with an M2 release last week, and we are getting a lot of interest, so now seems like a good time to give a few pointers.

Spring Batch 2.0 Themes

The four main themes of the new release are

  • Java 5 and Spring 3.0

  • Non-sequential execution

  • Scalability

  • Configuration: annotations and XML namespace

There are no changes to the physical layout of the project in Spring Batch 2.0.0.M2 (same old downloads, same basic layout of Java packages). We have not removed any features, but we have taken the opportunity to revise a couple of APIs, and there are some minor changes for people updating projects from 1.x. Spring Batch is immature enough and we were adding some pretty big features, so we decided a major version change was a good opportunity to have a bit of a clean out. We don’t expect anyone to have any difficulty upgrading, and if you are an existing user this article will help you to get the measure of the changes.


Understanding the OSGi uses Directive

If you build an application for the SpringSource dm Server, or any other OSGi platform, you’ll probably encounter the uses directive before long. Unless you have a clear understanding of the purpose of the directive, you won’t know when to code it and you’ll be left guessing when a bundle fails to resolve because of a uses conflict. This article should give you a thorough understanding of the uses directive, when to use it, and how to debug uses conflicts.

Bundle Resolution

OSGi is designed so that once bundles are ‘resolved’, you shouldn’t typically hit class cast exceptions and similar problems due to type mismatches. This is very important since OSGi uses a class loader for each bundle, so there is ample opportunity to expose users to various kinds of type mismatches.