Multi-User Chat (XEP-0045) [1] defines the protocol for groupchat in XMPP. In some situations, the room creator may want to request a unique room name before attempting to create the room (e.g., to avoid the possibility of a room conflict). Naturally, one way to do so is for the creator's client to generate a globally unique identifier, for example as defined in RFC 4122 [2]. Another way is for the client to ask the MUC service for a unique room ID (which the service will thus reserve for that user).
The room creator requests a unique room name by sending an IQ-get to the service itself, containing an empty <unique/> element qualified by the 'http://jabber.org/protocol/muc#unique' namespace:
<iq from='crone1@shakespeare.lit/desktop'
id='unique1'
to='chat.shakespeare.lit'
type='get'>
<unique xmlns='http://jabber.org/protocol/muc#unique'/>
</iq>
If the service supports this feature, it SHOULD return a unique room name as the XML character data of the <unique/> element (but not create the room):
<iq from='chat.shakespeare.lit'
id='unique1'
to='crone1@shakespeare.lit/desktop'
type='result'>
<unique xmlns='http://jabber.org/protocol/muc#unique'>
6d9423a55f499b29ad20bf7b2bdea4f4b885ead1
</unique>
</iq>
The service MAY refuse to return a unique room name to entities that are not entitled to create rooms, entities that have sent an excessive number of requests for unique room names, etc.
The service MAY use any algorithm that ensures the creation of a room name that will be permanently unique in the context of the service (e.g., a cryptographic hash of the requesting JID, datetime, and random salt), or simply use a UUID as defined by RFC 4122.
The room creator would then use the XML character data of the <unique/> element as the node identifier portion of the room JID it requests:
<presence
from='crone1@shakespeare.lit/desktop'
to='6d9423a55f499b29ad20bf7b2bdea4f4b885ead1@chat.shakespeare.lit/firstwitch'>
<x xmlns='http://jabber.org/protocol/muc'/>
</presence>
If a MUC service supports the protocol specified herein, it MUST advertise that fact by returning a feature of "http://jabber.org/protocol/muc#unique" in response to Service Discovery (XEP-0030) [3] information requests (see Protocol Namespaces regarding issuance of one or more permanent namespaces).
<iq from='crone1@shakespeare.lit/desktop'
id='disco1'
to='chat.shakespeare.lit'
type='get'>
<query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
<iq from='chat.shakespeare.lit'
id='disco1'
to='crone1@shakespeare.lit/desktop'
type='result'>
<query xmlns='http://jabber.org/protocol/disco#info'>
[...]
<feature var='http://jabber.org/protocol/muc#unique'/>
[...]
</query>
</iq>
<?xml version='1.0' encoding='UTF-8'?>
<xs:schema
xmlns:xs='http://www.w3.org/2001/XMLSchema'
targetNamespace='http://jabber.org/protocol/muc#unique'
xmlns='http://jabber.org/protocol/muc#unique'
elementFormDefault='qualified'>
<xs:element name='unique' type='xs:string'/>
</xs:schema>
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The Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself.
The primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list.
Discussion on other xmpp.org discussion lists might also be appropriate; see <http://xmpp.org/about/discuss.shtml> for a complete list.
Errata can be sent to <editor@xmpp.org>.
The following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL".
1. XEP-0045: Multi-User Chat <https://xmpp.org/extensions/xep-0045.html>.
2. RFC 4122: A Universally Unique IDentifier (UUID) URN Namespace <http://tools.ietf.org/html/rfc4122>.
3. XEP-0030: Service Discovery <https://xmpp.org/extensions/xep-0030.html>.
Note: Older versions of this specification might be available at http://xmpp.org/extensions/attic/
Initial published version.
First version, moved from XEP-0045.
END