Re: [emf-dev] exposing Ecore models via web services

[Ed Merks <ed.merks@xxxxxxxxx>]

Jacob,

Comments below.


Jacob Beard wrote:

Hi Ed,

Thanks for the quick response.

I have a few questions. I'd like to preface them by saying that I haven't done very much work developing Web Services before.

Me neither. I.e., none.

I'm mostly a web, front-end developer, albeit on the MDA and research side (I work on modeling the Abstract Syntax of Concrete Syntax, and on modeling UI behaviour).

Cool.  Sounds like more fun to me.

I'm therefore fairly familiar with consuming RESTful Web Services from the browser (particularly using dojo.data API's), but I haven't needed to expose these services myself, or deal with WS-* services.

Oh the horror.  That huge poster I blogged about a while back leaps to mind...

So some of these questions might be a bit newbish; please bear with me.

My answers might be naive as well.

In general, I'm concerned with finding the optimal way of exposing operations on EMF models to the browser via XMLHTTPRequest. If this has already been accomplished, and is document somewhere, then I believe this would resolve most the questions I'm about to put forward.

What's involved?  I know nothing about this.  It's of course easy enough to save something to XML and to load from XML bytes...

I see that Servus maps Ecore to WSDL 1.1 and 2.0, and generates client and server stubs in Java. Does this then marry us to SOAP?

Yet more horror.

It is my understanding that SOAP services cannot, in general be consumed directly by web browser clients (I think the reason most often cited is the lack of complete XML support across browsers), and so this could be problematic.

That may well be.

On the other hand, you said that EMF's resource design is fully RESTful. Could you please explain this a bit more, or point me to a resource that does?

Kenn's EclipseCon tutorial was about this topic.  Why weren't you there? :-P 

In https://bugs.eclipse.org/bugs/show_bug.cgi?id=191077 there is a little servlet that I used to test that save and delete work properly via HTTP.

In general REST is just a set of principles around the idea of  how the resources are uniformly addressed and the small number of operations that can be applied to those resources.  An EMF resource set effectively works like a browser where pages are like resources, addressed by a URI, and follow links opens new tabs.  How more RESTful can you be? :-P

Please let me know what you think. Thanks,

Jake

On Tue, Mar 24, 2009 at 3:08 PM, Ed Merks <ed.merks@xxxxxxxxx> wrote:

Jake,

Thiago did some work on Servus: 

http://wiki.eclipse.org/Servus

EMF's resource design is fully RESTful with the addition of delete support in last release.

Martin is doing some work on http://wiki.eclipse.org/Texo as well.

And I suppose I should complete the work for https://bugs.eclipse.org/bugs/show_bug.cgi?id=245014 but there's really not been that much interest in it....

Cheers,
Ed


Jacob Beard wrote:

Does anyone know of any previous work that has been done on exposing Ecore models via web services (RESTful or otherwise)? I'm starting to investigate this as I write my proposal, and I'm wondering if there are any resources that I can draw upon.

Please let me know. Thanks,

Jake

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