[wsrp] Links in a WSRP service: what do they mean?

[Sasha Aickin <AlexanderA@plumtree.com>]

Folks,

I brought up a question yesterday in the markup subgroup call that I would like to address to the whole group.  Basically, I think we need to have a clear idea what it means to have a link in a markup fragment returned by a WSRP service.  

Let's say we have some WSRP service A which returns an (X)HTML markup fragment that contains the text "<a href='http://someserver/resource.htm'>link</a>".  What should clicking this link do?  I see four possibilities:

(1)  link a user to http://someserver/resource.htm over straight, traditional HTTP without any proxying by the portal.
	This seems like a good idea if the linked resource is a large static file like an image.

(2)  link a user to http://someserver/resource.htm over straight, traditional HTTP with proxying by the portal.
	In this scenario, the portal would proxy the request to the resource, but it would not create a SOAP request.  This would be a good idea for large static files like images in situations where network connectivity does not allow the end user and the portlet server to talk directly.

(3)  link to WSRP service B at the URI http://someserver/resource.htm using SOAP
	This is useful if you want to delegate part of a WSRP service to another "sub-service".	

(4)  link to the same WSRP service A at the same URI using SOAP but pass in an argument of the form "linkClicked=http://someserver/resource.htm";
	This is useful if you want to stay in the same service and mimic URI links at the same time.

I think there are use cases for all four of these possibilities, and I think that they all make some sense.  However, I think that 3 & 4 are definitely not what links are supposed to be used for in (X)HTML, WML, & VXML, and I'm troubled by the idea that we might rewrite the semantics of markup tags with well established meanings.  I would propose that we define different linking mechanisms for cases (3) & (4) above through a different markup tag (e.g. <wsrplink>), through a new URI scheme (e.g. <a href="wsrp:blah"></a>), or through some other means.

Part of the problem here is that different resources returned by a single WSRP service (e.g. a portlet page, a detail view, a help page, an image) don't have actual different URIs, and so it is difficult to refer to them in hyperlinks in a way that is consistent with prior standards.  I think this is a major problem with the SOAP architecture we've chosen, and we should think about what workarounds there are to solve it.  Any ideas?

Cheers,
Sasha.