XRD – Extensible Resource Descriptor

XRD is a simple generic format for describing resources. Resource descriptor documents provide machine-readable information about resources (resource metadata) for the purpose of promoting interoperability, and assist in interacting with unknown resources that support known interfaces.

For example, a web page about an upcoming meeting can provide in its descriptor document the location of the meeting organizer’s free/busy information to potentially negotiate a different time. The descriptor for a social network profile page can identify the location of the user’s address book as well as accounts on other sites. A web service implementing an API protocol can advertise which of the protocol’s optional components are supported.

Specification

XRD is currently pending a second public review. The most recent draft is Working Draft 14 which was published on February 18th, 2010.

Recent posts on the subject:

• 2009 Year-End Status Report
• XRD Alignment with Link Syntax
• The Discovery Protocol Stack, Redux
• Host-meta (aka Site-meta) and Well-Known URIs
• Implementing WebFinger
• OpenID and LRDD
• Internet Identity Workshop, the Identity Geekfest
• XRD vs. XRDS, Side by Side Comparison
• (XRD) Weekly Recap
• The XRD Extensibility Model
• XRD Document Structure
• XRD-Based OAuth Discovery Sneak-Peek
• Conceptual Outline for XRD-Based OpenID Discovery
• XRD Sneak-Peek