The Spring Blog

News and Events

Dynamic DataSource Routing

Spring 2.0.1 introduced an AbstractRoutingDataSource. I believe that it deserves attention, since (based on frequent questions from clients) I have a hunch that there are quite a few ‘home-grown’ solutions to this problem floating around. That combined with the fact that it is trivial to implement yet easy to overlook, and now I have several reasons to dust off my corner of the team blog.

The general idea is that a routing DataSource acts as an intermediary - while the ‘real’ DataSource can be determined dynamically at runtime based upon a lookup key. One potential use-case is for ensuring transaction-specific isolation levels which are not supported by standard JTA. For that, Spring provides an implementation: IsolationLevelDataSourceRouter. Consult its JavaDoc for a detailed description including configuration examples.


Java to JavaScript Compilation with AJAX and Spring Integration

For some time I have been interested in client-centric, web-based user interfaces. These Generation IV frameworks are characterised by their component-based, event-driven programming model, and focus on the presentation logic residing entirely on the client. Targeting a web browser in this manner typically necessitates the use of JavaScript or Flash, which in itself imposes a number of unique challenges.

It is possible to address many of these challenges if we can program in Java and automatically produce a JavaScript or Flash runtime module. Two well-known products for achieving this today are Google Web Toolkit (GWT) and Open Laszlo respectively. Both are available under OSI-approved licenses and have active communities, together with their own unique complexity. One consideration is to what extent they fulfil an objective of providing a transparent Java-based development environment that targets web browser deployment. This consideration has several facets, including IDE support, debugging integration, reflective capabilities, runtime widget binding and alike. All of these are normal considerations when developing rich clients using traditional Java technologies such as Swing and Standard Widget Toolkit (SWT).


Spring IDE powering ahead

I had a great time at the Spring Experience conference last month. One pleasant surprise I had was the extent of the recent work the Spring IDE team have been doing. I ran into Spring IDE developer Christian Dupuis several times at the conference, and it seems that each time he’d implemented a new feature…

The forthcoming 2.0 release of Spring IDE is a comprehensive update to match the new features in Spring 2.0. And the Spring IDE team is making great progress with two of the big ticket items: XML extension namespaces and the AOP enhancements. (Btw, in case you’re wondering why I haven’t posted for a while, I spent a lot of time writing a Spring 2.0 update article over at InfoQ. This goes pretty deep with XML, AOP and core container features.)


Installing WebSphere Application Server 6.1 on Ubuntu

Recently I've been doing some work with a client on WAS 6.1. Since we have a number of Spring users on WAS and I need to test the application, I decided it was time to get a copy of WAS running on one of my work laptops. I say 'one of' because I'm currently working on both my Mac (with OSX) and my ThinkPad (with Ubuntu) - more recently I've just been using the ThinkPad because I can have Oracle XE and WAS running without the need for a VM tool like Parallels. I still prefer the Mac, but to be honest there isn't much difference day-to-day - I just miss some of the more useful Mac tools like Spotlight, Quicksilver, TextMate and NewsFire.


A Bridge Too Far

In my last entry I presented a technique for creating strategy classes that take full advantage of any generic metadata that is present in your application. At the end of that entry I showed this code snippet:

EntitlementCalculator calculator = new DividendEntitlementCalculator();
calculator.calculateEntitlement(new MergerCorporateActionEvent());

You'll remember that DividendEntitlementCalculator was defined as:

public class DividendEntitlementCalculator implements EntitlementCalculator<DividendCorporateActionEvent> {

    public void calculateEntitlement(DividendCorporateActionEvent event) {


Unit Testing with Stubs and Mocks

I was on site with some clients the other day, and they asked me about unit testing and mock objects. I decided to write up some of the discussion we had as a tutorial on creating dependencies (collaborators) for unit testing. We discuss two options, stubbing and mock objects and give some simple examples that illustrate the usage, and the advantages and disadvantages of both approaches.

It is common in unit tests to mock or stub collaborators of the class under test so that the test is independent of the implementation of the collaborators. It is also a useful thing to be able to do to control precisely the test data that are used by the test, and verify that the unit is behaving as expected.


Spring Web Flow 1.0.1 Released

Dear Spring Community,

We are pleased to announce that Spring Web Flow 1.0.1 has been released.


Spring Web Flow is a next generation Java web application controller framework that allows developers to model user actions as high-level modules called flows.  The framework delivers improved productivity and testability while providing a strong solution to enforcing navigation rules and managing application state.


What's New and Cool in Spring 2.0?

Last month Rod Johnson presented at three Australian Spring User Group meetings a session entitled, “What’s New and Cool in Spring 2.0”. Rod mentioned during those meetings that I’d make his presentation available, so here it is.

There are some other recent presentations that people have also been emailing me about. In no particular order, here is the latest:


Why the name Interface21?

A few weeks ago I blogged about the origins of the name Spring. We also get many questions about the origins of the name Interface21.

For anyone who’s read my books or considered the design of Spring, the interface part is hardly a surprise. It plays on both the OO concept of an interface (for which I’ve always had a deep love) and the notion of the interface to a system. For example, putting a web interface onto an existing green screen system–something I was actually doing when I first thought of the company name.