As we are just starting on a project where we need to provide access to our Cocoon based solution via a web service centric approach I have been musing around about the best way to achieve this.
Now to start with Cocoon is really ideal for web services. Basically it already is capable of providing a web service platform. After all you can communicate with it using HTTP and XML - so it already caters for two of the requirements. And Cocoon allows you to define "services" flexibly by configuring components into pipelines as you need them. The ability to actually use Cocoon as an XML application platform - as opposed to (just) an XML publishing platform will increase as more and more components are developed. However it has one major drawback (in the world of web services): It does not provide a way of describing the available functions (read: pipelines) in a standardized manner (read: WSDL). But let's look at this step by step. Cocoon as web service client The client side (i.e. integrating services into a Cocoon based solution) is pretty easy. One way is to write a custom transformer dependent on the spec of the service (or using the WSDL). Of course an ideal solution would allow me to generate a transformer using the WSDL automatically (hint). There are also several ways of doing this. One way is to use something like WSDL2Java from Axis and then perform a further step that generates a transformer from the classes WSDL2Java spits out. Another way would be to hook directly into the flow that emits the Java code in Axis. Another way of writing the client side is to use XSP and that has been discussed before so I'll leave it at that. Cocoon as web service server Ok, this is where it gets more interesting. Here is basically what _we_ need: Publish a pipeline (set of pipelines) as a web service accessible via SOAP and providing a self-description in WSDL. Apart from the last part (which I really think is just as important as the first - if we think Cocoon can become a platform for WS) there are several approaches that would probably work: * Use XSL in a pipeline that interprets the SOAP request and then passes off to the appropriate pipeline * Use the Kinga/HP approach of the Adapter/Dispatcher model with additional SOAP stuff * Integrate Axis Personally I think we should be looking at working with the Axis project and integrating it into Cocoon. Here are my reasons: * They are hard at work on the interop side of web services * The architecture is flexible and uses SAX * The architecture allows you to hook in nearly everywhere (handlers, pivots,...) * You get tools for free * It's Apache :-) Now, I do not (yet?) understand enough about the current Axis code and I am now quite a bit removed from actually implementing (as Carsten likes to remind me) to start to give any roadmap as to how it would be possible - but here are a few ideas. The first step would be to install the Axis servlet parallel to the Cocoon servlet and write a service, handler, pivot that can bridge into Cocoon. One simple way would be to hook into the SOAP processing and call the relevant pipeline based on what is sent. Later we could then merge the servlets so that we only have one endpoint. But then again having it seperate may allow better scalability. Ok, so then how can we publish a pipeline as WSDL? Well perhaps we can use Views for that. Something like a WebService view that the bridging class can then turn into WSDL. Axis allows WSDL generation on the fly if you append "?wsdl" to the URI. So maybe something there would work. It is not that I don't think the HP solution is a good idea and perhaps it fits Cocoon even better than Axis would. However at the moment I would be very interested in how the HP solution caters for stuf like WSDL. Does it? I know I am repeating this but: If we think Cocoon can move in this direction then we really really need some way of generating WSDL from a set of pipelines. Imagine firing up Visual Studio .Net and being able to generate a Visual Basic program that can call a Cocoon pipeline - just by accessing the WSDL that the pipeline has provided. Ok, so any comments welcome. Fire away. Matthew Langham ________________________________________________________________ Keine verlorenen Lotto-Quittungen, keine vergessenen Gewinne mehr! Beim WEB.DE Lottoservice: http://tippen2.web.de/?x=13 --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
