Subject: Re: link relations and links in general

From: Erik Wilde <[email-masked]>
Date: Wed, 01 Jul 2009 10:14:29 -0700

hello subbu.

Subbu Allamaraju wrote:
>>> I suspect that this is heading towards XLink.
>> not really. the important difference is that XLink links instances (it 
>> specifies links for concrete URIs), whereas LDX specifies how to 
>> discover links in media types. i think this is an important 
>> difference, and my post definitely failed to be very specific about 
>> this. the reason why i think it's important is that REST centers 
>> around media types and following links, and LDX should be a god match 
>> with that.
> Ah I see. Just read your post again. I don't think link discovery on its 
> own solves anything, unless the author of the  representation or the 
> media type says something about a link appearing at any given position 
> an an XML document.

that's exactly what he's doing wih LDX: an XPath can be as specific as 
required by the media type and can specifically only select one link 
somewhere, or all links anywhere (think about //html:img/@src, for 
example, selecting all links to images in XHTML). then you associate 
information with that link in the form of the link relation, the 
resulting media type, or the expected URI template. this kind of 
description makes it much easier for consumers of RESTful services to 
discover and understand the links they'll find in XML resources. i am a 
bit confused why you think that this does not solve anything. it 
definitely does not solve everything in the sense that you can readily 
generate code from it to automatically implement an application, but it 
certainly would be good enough to for example drive a "link discovery" 
component of a REST toolbox, or maybe to just serve as documentation for 
RESTful services independent of the schema language used for the media 
types exposed by the service.

cheers,

erik wilde   tel:+1-510-6432253 - fax:+1-510-6425814
        [email-masked]  -  http://dret.net/netdret
        UC Berkeley - School of Information (ISchool)