XML_XRD
XML_XRD is a PHP library to parse and generate Extensible Resource Descriptor (XRD) Version 1.0 and JRD (JSON-based) files.
XRD files are used for .well-known/host-meta
files as standardized in
RFC 6415: Web Host Metadata
as well as in the
LRDD (Link-based Resource Descriptor Discovery)
files linked from it.
JRD files are used by WebFinger, which lets people use their e-mail address to do OpenID sign in.
The XRD format supercedes the XRDS format defined in XRI 2.0, which is used in the Yadis communications protocol.