November 29, 2007

When the company formerly known as Interface21 introduced the second version of its flagship offering, the commercial distribution of the Spring framework, it made a pact with the devil to support Java Annotations, a pillar of the Java EE 5 spec. In the follow-on version, 2.5, the company has expanded on that support and clarified the scenarios where annotations are, and are not suitable, as part of a strategy to let customers have it both ways.

And, lest we forget, the company has changed its name from Interface21 to SpringSource. But we’ll get to that later – first we’ll deal with the product changes.

Besides expanded support of Java annotations, other new features include enhanced support for Web MVC (model-view-controller), either using Struts or Spring’s own versions, support for bundling of Spring components via OSGi, plus fill-in-the-blanks features like support of Java 6 and Java EE 5 APIs.

 “The key to the new release is that it gives you new options for configuration,” explained SpringSource founder and CEO Rod Johnson.

It starts with Java Annotations, a feature introduced with Java EE 5 to simplify Java development by allowing developers to use meta tags that specify various parameters of the code. Examples include descriptors of the code package, data types, methods, fields invoked, variables, or other parameters that are involved. In essence, it’s a form of shorthand for invoking the annotation, and having the framework automatically populate it, rather than having to code from scratch.

The problem, maintains Johnson, is that when Java code is repurposed, the annotations could easily fall out of sync. “There is danger in the excess use of annotations, which is why it's taken awhile to deliver a comprehensive solution to market.”

So SpringSource ate its pride and came out with a product that lets you use Java annotations or its own method, where you use Spring’s external XML descriptors. So you can annotate Java classes as you normally would, then have the Spring framework automatically discover them and populate its own external XML descriptors, or you can simply use Spring’s XML descriptors to provide the shorthand for generating your Java routine.

The new version continues support of several other features that compete with established practice, including SpringSource’s Web Flow, which models user navigation through a web application. The new revision of Web Flow adds its own model-view-controller (MVC, a classic software engineering pattern for separating data from presentation and logic) instead of that provided by the popular Apache open source framework Struts (the SpringSource offering also lets you use Struts). Johnson calls the web flow and MVC combination, ”a unified web tier solution,” claiming that the SpringSource MVC is more flexible than the better-known Struts alternative. Another aspect of the new release of Web Flow is better integration with JSF, which provides a component model for web pages, but does not address navigation.

The other major highlight of the new release is support of packaging using the OSGi component model. Although initially developed for home set top boxes, OSGi’s ability to dynamically hot swap and provision new components was seized upon by the Eclipse Foundation as the new model for deploying plug-ins. In this release, SpringSource adopts OSGi for bundling libraries of the Spring framework. The advantage is that OSGi makes Spring more modular, so you can deploy only what you need, when you need it, without taking the system offline.

Oh, and as to that name change, it’s one of those cases where the technology had much greater name recognition than the company. Yes, Interface21 was a fitting name, because the Spring framework presented a new way of dealing with Java interfaces and dependencies. But as Johnson noted, only techies understood that. “We kept getting questions, ‘how do you related to Spring?’ “ recalled Johnson.

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