XRDS Ancestry

Just for fun, and because I couldn't make it to OpenIDDevCamp,  I thought I'd go back and recount history of the XRDS/XRD schema/concept. The use of the XRD/XRDS for stuff outside XRI was proposed at the IIW 2005 in Berkeley (in what became YADIS), but there's a ton of earlier history...

I believe the first time an extensible XML document format was proposed for the result of XRI resolution was in I think the first time an XML format which resembles what we have today was proposed was in Sep 2003:
http://www.oasis-open.org/archives/xri/200309/msg00000.html 

Before that, I think we had been focusing more on using DNS records for resolution (specifically DDDS or SRV or other mechanisms). That document format described what we called at the time "Local Access" service endpoints. They were basically REST endpoints. This was basically the document format that ended up in XRI 1.0... very tailored to the XRI Resolution mechanism and limited to the concepts within XRI (which were admittedly a little unique...) Trusted resolution soon followed (a chain of digitally signed XRD's to ensure the resolution results were authentic). 

XRI 2.0 changed the descriptor format that resulted from XRI resolution. By Feb of 2005, an XRID (XRI Descriptor - that name lasted until very recently) format that resembles today's XRD had been proposed:
http://www.oasis-open.org/committees/download.php/11482/xri20res.pdf 

The XRI syntax and XRI resolution mechanisms were put into separate specs, not because we thought the resolution spec would be used outside XRI, but rather because we anticipated multiple resolution mechanisms for XRIs and wanted to keep the two specs separate to allow them to evolve independently. 

There was a long and (one of many many many) heated discussion about whether XRI resolution services should be described in the same way as other services - that is, whether a Service element should be used to describe endpoint services as well as XRI resolution servers. We had, for a long time, treated those as very different things described with separate elements. The final big change to XRDS/XRD was to make XRI authority resolution "just another service" from the point of view of the XRDS/XRD schema definition. It wasn't until Nov 2005 that the XRI authority was "demoted" to "just another service" in working draft 09 of XRI Res 2.0:
http://www.oasis-open.org/committees/download.php/15310/xri-resolution-V2.0-wd-09.pdf 

The motivation for this conceptual change is documented in section 6 of the document found here: 
http://www.oasis-open.org/committees/download.php/14641/proposed-resolution-use-cases-and-reqs-v1.doc  

and discussed here: 
http://www.oasis-open.org/archives/xri/200510/msg00042.html 

In fact, I had recommended at the time that XRI resolution exclude service description altogether, suggesting that surely formats like RDDL or other descriptor formats could be used. That was roundly rejected, as described in minutes documented here: 
http://www.oasis-open.org/archives/xri/200510/msg00040.html 

We went ahead and included service description as part of the XRI resolution spec and I guess I'm glad I was wrong... 

     -Gabe