XEP-0186: Invisible Command

Peter Saint-Andre

Email: stpeter@jabber.org
JID: stpeter@jabber.org

1. Introduction

2. Requirements

3. Use Cases

3.1. Discovering Support

3.2. User Becomes Invisible

3.3. User Becomes Visible

4. Security Considerations

5. IANA Considerations

6. XMPP Registrar Considerations

6.1. Protocol Namespaces

7. XML Schema

Notes

Revision History

3.1 Discovering Support

In order for a client to discover whether its server supports the protocol defined herein, it MUST send a Service Discovery [5] information request to the server:

Example 1. Service discovery request

<iq from='bilbo@tolkien.lit/shire' to='tolkien.lit' type='get' id='disco1'>
  <query xmlns='http://jabber.org/protocol/disco#info'/>
</iq>
    

If the server supports the protocol defined herein, it MUST return a feature of "http://jabber.org/protocol/invisibility":

Example 2. Service discovery response

<iq from='bilbo@tolkien.lit/shire' to='tolkien.lit' type='get' id='disco1'>
  <query xmlns='http://jabber.org/protocol/disco#info'>
    ...
    <feature var='http://jabber.org/protocol/invisibility'/>
    ...
  </query>
</iq>
    

A client SHOULD complete this service discovery process before sending initial presence to its server.

3.2 User Becomes Invisible

In order for a client to go invisible, it shall send an IQ-set with no 'to' address (thus handled by the user's server) containing an <invisible/> element qualified by the 'http://jabber.org/protocol/invisibility' namespace:

Example 3. Invisible command

<iq type='set' id='inv1'>
  <invisible xmlns='http://jabber.org/protocol/invisibility'/>
</iq>
    

If the server can successfully process the invisibility command, it MUST return an IQ-result:

Example 4. Invisible command is successful

<iq type='result' id='inv1'/>
    

(Standard XMPP stanza errors apply; see RFC 3920 and Error Condition Mappings [6].)

If the client enters invisible mode after having previously sent undirected presence with no 'type' attribute (e.g., after sending initial presence), the server MUST send <presence type='unavailable'/> presence from the client's resource to all contacts who would receive unavailable presence if the client sent <presence type='unavailable'/>.

While the client is in invisible mode, the server:

1. MUST NOT broadcast presence notifications as a result of receiving any subsequent undirected presence notifications from the client.

2. MUST deliver directed presence stanzas generated by the client.

3. MUST deliver inbound <presence/> stanzas.

4. SHOULD deliver inbound <message/> stanzas whose 'to' address is the bare JID of the user (subject to standard XMPP stanza handling rules).

5. MUST deliver inbound <message/> and <iq/> stanzas whose 'to' address is the resource of the client.

6. MUST deliver outbound <message/> and <iq/> stanzas generated by the client (for an important note regarding presence leaks, see the Security Considerations section of this document).

If after sending directed presence the client then sends <presence type='unavailable'/>, the server MUST deliver that unavailable presence only to the entities to which the client sent directed presence after going invisible.

3.3 User Becomes Visible

In order for a client to become visible again, it shall send an IQ-set with no 'to' address (thus handled by the user's server) containing a <visible/> element qualified by the 'http://jabber.org/protocol/invisibility' namespace:

Example 5. Visible command

<iq type='set' id='vis1'>
  <visible xmlns='http://jabber.org/protocol/invisibility'/>
</iq>
    

If the server can successfully process the visibility command, it MUST return an IQ-result:

Example 6. Visible command is successful

<iq type='result' id='vis1'/>
    

When the client becomes visible, the server MUST treat that state as equivalent to an active session before receiving initial presence from the client. It is the responsibility of the client to send an undirected presence notification to the server, which the server MUST broadcast to all entities who would normally receive presence broadcasts from the client (as well as any other entities to which the client sent directed presence while invisible).

6.1 Protocol Namespaces

The XMPP Registrar [8] shall include 'http://jabber.org/protocol/invisibility' in its registry of protocol namespaces (see <http://www.xmpp.org/registrar/namespaces.html>).

<?xml version='1.0' encoding='UTF-8'?>

<xs:schema
    xmlns:xs='http://www.w3.org/2001/XMLSchema'
    targetNamespace='http://jabber.org/protocol/invisibility'
    xmlns='http://jabber.org/protocol/invisibility'
    elementFormDefault='qualified'>

  <xs:element name='invisible' type='empty'/>

  <xs:element name='visible' type='empty'/>

  <xs:simpleType name='empty'>
    <xs:restriction base='xs:string'>
      <xs:enumeration value=''/>
    </xs:restriction>
  </xs:simpleType>

</xs:schema>
  

1. XEP-0018: Invisible Presence <http://www.xmpp.org/extensions/xep-0018.html>.

2. RFC 3920: Extensible Messaging and Presence Protocol (XMPP): Core <http://www.ietf.org/rfc/rfc3920.txt>.

3. RFC 3921: Extensible Messaging and Presence Protocol (XMPP): Instant Messaging and Presence <http://www.ietf.org/rfc/rfc3921.txt>.

4. XEP-0126: Invisibility <http://www.xmpp.org/extensions/xep-0126.html>.

5. XEP-0030: Service Discovery <http://www.xmpp.org/extensions/xep-0030.html>.

6. XEP-0086: Error Condition Mappings <http://www.xmpp.org/extensions/xep-0086.html>.

7. 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/>.

8. 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 <http://www.xmpp.org/registrar/>.

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