Spring is going Webservices! Or a bit more specific, Spring is going SOAP. Arjen Poutsma has sent this message to the world during the last NL-JUG J-Fall conference. On his blog you can find the nitty gritty details.

Personally I think it is a good idea to build a Spring based framework and not be dependant on special web service containers. But I can’t see the point of focusing on SOAP only. I know SOAP is the de-facto standard for building message based remote services. And I also see the point he’s making about the difference between message based and rpc-style invocation. But I do not see the reason to ignore other protocols. To express this, REST is mentioned in one of Arjens blogs: REST services seem to have very little common functionality that cannot already be captured with Java classes like the HttpServlet.

Okay, agree. But so what? Maybe I need to publish my beans as both SOAP and REST service? Maybe I’m stuck with a legacy message format? Maybe, for performance reason, I do not want to use SOAP? Maybe I’m not running on a servlet container but behind my own socket? And maybe I can come up with a lot more maybe’s? Both SOAP and REST are message driven protocols that share some common similarities. And those similarities can be expressed in a common interface or abstract set of classes. Loose coupling is one of the paradigma’s lite weight application design has been build upon! So, either convince me I’m wrong or extend your horizon in order to do remote invocation beyond SOAP.

By the way, a little side-step into API design. Suppose you have two interfaces specifying a method with the same name but a different return type, how on earth are you going to implement it in one class? So SOAPMessage invoke(SOAPMessage request) throws Exception in MessageEndpoint and Source invoke(Source request) throws Exception in PayloadEndpoint is maybe not a good idea. I know chances a rare in this case but you’ll never know how the dices will be thrown when you start playing.

[editorial note, I need to re-pass Sun certification. Please visit the comments section for clarification]

But, no matter if the people behind Spring-WS are going to change the previous mentioned points or not, I think Spring-WS is a good addition to the stack of available Spring modules. And definately worth the try!