This document defines two XMPP protocol extensions for communicating URIs between Jabber entities, where the data formats are qualified by the 'jabber:iq:oob' and 'jabber:x:oob' namespaces. Although these mechanisms were originally used for out-of-band (OOB) data transfer, they are also used more generally to exchange or communicate URIs.

The intent of the 'jabber:iq:oob' was to provide a "least common denominator" mechanism for basic file transfers.

To initiate an out-of-band file transfer with an intended recipient using the 'jabber:iq:oob' namespace, the sending application sends an <iq/> of type 'set' to the recipient containing a <query/> child element qualified by the 'jabber:iq:oob' namespace; the <query/> MUST in turn contain a <url/> child specifying the URL of the file to be transferred, and MAY contain an optional <desc/> child describing the file. This usage is shown in the following example.

The expected result is for the recipient to retrieve the file via an HTTP GET request and to then inform the sender of successful receipt of the file. The receiving application MUST NOT send the IQ result until it has retrieved the complete file (e.g., it MUST NOT send the IQ result if it has merely attempted to retrieve the file or the URL provided seems to be valid):

If the recipient attempts to retrieve the file but is unable to do so, the receiving application MUST return an <iq/> of type 'error' to the sender specifying a Not Found condition:

If the recipient rejects the request outright, the receiving application MUST return an <iq/> of type 'error' to the sender specifying a Not Acceptable condition:

The 'jabber:x:oob' namespace is used to communicate a URI to another user or application. This is done by including an <x/> child element qualified by the 'jabber:x:oob' namespace in either a <message/> and <presence/> stanza; the <x/> child MUST contain a <url/> child specifying the URL of the resource, and MAY contain an optional <desc/> child describing the resource.

If an entity supports the out of band data protocol, it MUST report that by including a service discovery feature of "jabber:iq:oob" and/or "jabber:x:oob" in response to a Service Discovery (XEP-0030) XEP-0030: Service Discovery <https://xmpp.org/extensions/xep-0030.html>. information request:

The value of the <url/> element is not limited to URIs that conform to the http: URI scheme (as specified by RFC 2616 RFC 2616: Hypertext Transport Protocol -- HTTP/1.1 <http://tools.ietf.org/html/rfc2616>.). For example, file transfers could also be effected using ftp: URIs as (specified by RFC 959 RFC 959: File Transfer Protocol <http://tools.ietf.org/html/rfc0959>.). Going further afield, several existing Jabber clients use the callto: URI scheme to initiate voice conferencing via NetMeeting or GnomeMeeting. Other out-of-band communications could be initiated in a similar way via URI schemes such as sip: (as specified by RFC 3261 RFC 3261: Session Initiation Protocol (SIP) <http://tools.ietf.org/html/rfc3261>.). All of these usages are allowed by the existing OOB namespaces, as long as the value of the <url/> element is a valid URI (as specified by RFC 3986 RFC 3986: Uniform Resource Identifiers (URI): Generic Syntax <http://tools.ietf.org/html/rfc3986>.).

Up to and including revision 1.5 of this XEP, this section defined a non-normative integration with Stream Initiation, itself deprecated. To retain section numbering, this text remains as a placeholder.

As with any mechanism that communicates a URI, care must be taken by the receiving application to ensure that the resource retrieved does not contain harmful or malicious data (e.g., a virus-infected file).

This document requires no interaction with the Internet Assigned Numbers Authority (IANA) The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>..

The 'jabber:iq:oob' and 'jabber:x:oob' namespaces are included in the protocol namespaces registry maintained by the XMPP Registrar The XMPP Registrar maintains a list of reserved protocol namespaces as well as registries of parameters used in the context of XMPP extension protocols approved by the XMPP Standards Foundation. For further information, see <https://xmpp.org/registrar/>. (see <https://xmpp.org/registrar/namespaces.html>).