The OpenSocial v0.8 RESTful API Specification specifies the use of XRDS-Simple for autodiscovery.

On the other hand, the RESTful API used in OpenSocial v0.8 is in the AtomPub format, and AtomPub specifies the use of a Service Document.

This leaves open the question of which container site should use, and whether they should use both. I posed a question to the Google Groups OpenSocial specification group.

question

Should a container site adopt AtomPub's Service Document or XRDS-Simple? Should it support both?

Answer by David Primmer

AtomPub's Service Document is not suitable for defining parts of a URL as a template and assigning variables. It seems to be designed to be specified on a relatively fixed URL. XRDS-Simple excels in that it allows you to discover URLs by filling in the blanks.

Regarding this point, [Takemaru], who implemented the AtomPub Perl library, also pointed it out, and we agree that using XRDS-Simple is more reasonable.

However, it's certainly unsightly in terms of not conforming to the specification, and I'm wondering if this issue can be resolved somehow. I asked the AtomPub spec creators on the Google Groups I mentioned earlier whether they planned to propose changes to the specification, but I haven't received a response since.

At present, Rod Yates has suggested that we could apply this specification, so we will consult with AtomPub experts and make some kind of effort to address this.