%ents; ]>
User Nickname This document defines a protocol for communicating user nicknames. &LEGALNOTICE; 0172 Draft Standards Track Standards Council XMPP Core nick http://www.xmpp.org/schemas/nick.xsd &stpeter; &val; 1.0 2006-06-05 psa

Per a vote of the Jabber Council, advanced status to Draft.

 0.9 2006-05-10 psa

Added pubsub examples.

 0.8 2006-04-28 psa

Clarified terminology; explicitly mentioned that nicknames must not be included in presence broadcasts (only subscription requests); added implementation note about display names.

 0.7 2006-04-21 psa/vm

Added further detail to waitlist example; added schema.

 0.6 2006-03-27 psa

Specified security considerations.

 0.5 2006-03-22 psa

Fixed MUC invite example; clarified that nick refers to entity associated with nearest ancestor element that specifies a sender; added waitlist example.

 0.4 2006-03-20 psa

To reflect use of dedicated namespace, (1) changed document type from Informational to Standards Track and (2) updated XMPP Registrar Considerations.

 0.3 2006-03-16 psa/vm

Modified to use dedicated namespace; added example for multi-user chat invitations.

 0.2 2006-03-08 psa

Added wrapper element from XEP-0154.

 0.1 2006-01-24 psa

Initial version.

 0.0.3 2006-01-22 psa/vm

Added message exchange use case.

 0.0.2 2006-01-18 psa/vm

Added MUC and nickname management use cases; specified profile data syntax.

 0.0.1 2005-09-12 psa

Initial version.

A nickname is a global, memorable (but not necessarily unique) friendly or informal name chosen by the owner of a bare JID &LOCALBARE; for the purpose of associating a distinctive mapping between the person's unique JID and non-unique nickname. While nicknames have been a common feature of instant messaging systems for many years, they have not always featured prominently in Jabber/XMPP IM systems (e.g., nicknames are not specified in &rfc3921;). However, there are several reasons why nicknames are important:

This document defines best practices that enable IM users to advertise their preferred nicknames over Jabber/XMPP instant messaging networks.

This proposal draws a distinction between the following kinds of names, where a JID is an innate feature of a user's identity on an XMPP system, a nickname is asserted by a user, and a handle is assigned by a contact to a user.

Name Definition
Jabber ID (JID) A global and unique XMPP identifier registered to a particular user, of the form &LOCALBARE;; represented in the 'from' attribute of XML stanzas sent by that user, the 'jid' attribute of items associated with that user in a contact's roster, etc.
Nickname A global and memorable (but not necessarily unique) friendly name or informal name asserted by an IM user. Typically, a nickname is different from a familiar name, such as "Chuck" for "Charles", "Bill" for "William", "Pete" for "Peter", or "Dave" for "David"; instead, a nickname is even less formal, such as "stpeter" or "dizzyd". A nickname is thus typically different from a "display name" as that term is understood in SMTP (see &rfc2821;) and SIP (see &rfc3261;).
Handle A private, unique, and memorable "petname" or "alias" assigned by a contact to a user; represented in the 'name' attribute of the item associated with that user's JID in the contact's roster. In RFC 3921, the name here called a "handle" is described as an "alias"; rfc3921 will be modified to use the term "handle" instead.

A nickname MUST be encapsulated as the XML character data of a <nick/> element qualified by the 'http://jabber.org/protocol/nick' namespace. Here is an example:

Ishmael ]]>

A nickname of this form has the same semantic meaning as the following data fields:

The entity to which the <nick/> refers is the from address (no matter how encapsulated in XML) of the nearest ancestor element that specifies the sender (which might be a parent or grandparent element, e.g. the 'from' attribute of an &IQ; stanza).

In general, a user SHOULD include his or her nickname when establishing initial communication with a contact or group of contacts (i.e., the user has never been in communication with and does not have a prior relationship with the contact or group of contacts). Appropriate use cases therefore include:

As defined in RFC 3921, a presence subscription request contains only the JID of the sender:

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Naturally, based on the JID of the sender, it is possible for the client to pull information about the sender from a persistent data store such as an LDAP database, &xep0054; node, or XEP-0154 store. However, to speed interactions, this document recommends that when a client sends a subscription request, it SHOULD include the preferred nickname of the sender:

Ishmael ]]>

Note: This document recommends sending the nickname only in presence subscription requests; the nickname MUST NOT be included in presence broadcasts (i.e., &PRESENCE; stanzas with no 'type' attribute or of type "unavailable").

When a user begins to chat with a contact but the two parties have no pre-existing relationship or prior communications (e.g., no presence subscription or previous message exchange), the user SHOULD include the nickname with the first message sent to the contact:

Call me Ishmael Ishmael ]]>

&xep0045; defines a protocol for groupchat rooms. A user specifies a "room nickname" when joining such a room (the resource identifier of the 'to' address):

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A user MAY specify his or her persistent nickname as well. This may be desirable because the user's preferred room nickname is already taken or because the service "locks down" room nicknames.

Ishmael ]]>

If a user includes his or her persistent nickname in the room join request, the nickname SHOULD also be included in any presence changes sent to the room:

away writing Ishmael ]]>

A nickname may also be included in a MUC room invitation:

Ishmael ]]>

Although the foregoing stanza may seem to violate the rule about associating a nick with the nearest ancestor element that specifies the sender's JID, the output from the MUC room does not violate that rule, since the room swaps the to and from addresses before sending the invitation to the invitee:

Ishmael ]]>

&xep0130; defines a protocol that enables a user to be informed when a contact signs up for an IM account. The user MAY include his or her nick in the request so that the contact can associate a nickname with the request.

+45-555-1212 Ishmael ]]>

Naturally, the WaitingListService SHOULD pass the nick on to its InteropPartners as well:

contact-number Ishmael ]]>

If an InteropPartner knows a contact's nickname when it returns results to the WaitingListService it SHOULD include the nickname:

contact-number Starbuck ]]>

Finally, if the user's waiting list service knows the contact's nickname when it sends a notification to the user, it SHOULD include the nickname:

This message contains a WaitingList item. +45-555-1212 Starbuck ]]>

In order for a user to modify his or her nickname and notify contacts of that change, it is RECOMMENDED for clients to use &xep0163; (a.k.a. PEP).

CallMeIshmael ]]> CallMeIshmael
. . . ]]>

If a XEP-0163-compliant personal eventing service is not available, a client SHOULD use a standalone &xep0060; service.

CallMeIshmael ]]> CallMeIshmael
. . . ]]>

If a client does not support XEP-0060 or the subset thereof specified in XEP-0163, it MAY send one &MESSAGE; stanza to each of its contacts, containing the updated nickname (note: the client SHOULD send the messages in a staggered fashion in order to avoid server-enforced rate limiting, commonly known as "karma").

CallMeIshmael . . . ]]>

An IM client MAY use the user's own nickname as all or part of the "display name" shown to the user of that client (e.g., as the sending name in one-to-one chats and groupchats). For example, if the user whose JID is narrator@moby-dick.lit asserts that his nickname is "Ishmael", that user's client may show "Ishmael" as all or part of the user's display name. How the client shall store the display name is out of scope for this document; possible mechanisms include the user's local vCard, an organizational LDAP directory, &xep0049;, or XEP-0154.

A nickname is a memorable, friendly name asserted by a user. There is no guarantee that any given nickname will be unique even within a particulat community (such as an enterprise or university), let alone across the Internet through federation of communities. Clients SHOULD warn users that nicknames asserted by contacts are not unique and that nickname collisions are possible. Clients also MUST NOT depend on nicknames to validate the identity of contacts; instead, nicknames SHOULD be used in conjunction with JIDs (which are globally unique) and user-assigned handles (which are private and unique) as described in XEP-0165 in order to provide a three-pronged approach to identity validation, preferably in combination with X.509 certificates.

This document requires no interaction with &IANA;.

The ®ISTRAR; includes 'http://jabber.org/protocol/nick' in its registry of protocol namespaces (see &NAMESPACES;).

 The protocol documented by this schema is defined in XEP-0172: http://www.xmpp.org/extensions/xep-0172.html ]]>

Thanks to Ian Paterson for his feedback.

Unbeknownst to the authors of this document, work on user nicknames was previously done by Richard Dobson (see <http://richard.dobson-i.net/xep.php?html=xep-01xx.xml>).