&w3html; defines a <link/> element that defines a relationship between a document and another resource on the Internet. Such a resource can be a JabberID. Examples include the JabberID of a document author, a &xep0045; room where the document can be discussed, or a &xep0060; node where RSS or Atom feeds related to the document are hosted (e.g., see &rfc4287;). This specification defines a recommended approach for linking to JabberIDs in this way.

The RECOMMENDED format is as follows.

The 'href' attribute is REQUIRED and its value MUST be an XMPP URI or IRI that conforms to &rfc5122;. The URI SHOULD NOT include an action as described in &xep0147; and registered at &QUERYTYPES;, so that the URI can be appropriately dereferenced as described below. The URI MAY include a node key as shown in the examples below.

The 'rel' attribute is RECOMMENED and its value SHOULD be a link relation as registered in the &ianalinks; or other registry.

In addition to 'href' and 'rel', the HTML and XHTML specifications define a number of other allowable attributes for the <link/> element. These attributes MAY be included. However, because a JabberID is a bare address and there is no hosted media associated with a JabberID, the 'charset', 'media', and 'type' attribute SHOULD NOT be included.

When an application encounters an auto-discovery link to a JabberID, it SHOULD pass it to an appropriate helper application (such as an XMPP client). The helper application then SHOULD dereference the URI, and send an XMPP &xep0030; request to the referenced JID, passing the optional node parameter. The service discovery response therefore enables a full range of future actions.

The following example shows a JabberID that points to the same entity as the document itself (e.g., the author of an "about-the-author" page).

The following example shows a JabberID that points to a multi-user chat room where the document can be discussed.

The following example shows a JabberID that points to a publish-subscribe node where notifications related to the document can be retrieved.

Advertising an XMPP address so that it can be automatically discovered may expose that address to abusive communications. Care should be taken when choosing whether to advertise a JID that corresponds to an end user's primary XMPP address.

This document currently requires no interaction with &IANA;. However, a future version of this specification may register new link relations with the IANA.

This document requires no interaction with the ®ISTRAR;.