RFC 6120, "Extensible Messaging and Presence Protocol (XMPP): Core", March 2011

Note: This RFC has been updated by RFC 7590, RFC 8553

Errata ID: 4741
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: Sam Whited
Date Reported: 2016-07-13
Held for Document Update by: Ben Campbell
Date Held: 2016-07-13

Section 8.2.3 says:

1.  The 'id' attribute is REQUIRED for IQ stanzas.

…

3.  An entity that receives a stanza of type "get" or "set" MUST
    reply with an IQ respones of type "result" or "error".  The
    response MUST preserve the 'id' attribute of the request (or be
    empty if the generated stanza did not include an 'id' attribute).

It should say:

1.  The 'id' attribute is REQUIRED for IQ stanzas.

…

3.  An entity that receives a stanza of type "get" or "set" MUST
    reply with an IQ respones of type "result" or "error".  The
    response MUST preserve the 'id' attribute of the request, or
    send an appropriate error if the generated stanza did not
    include an 'id' attribute.

Notes:

If the received IQ had an empty ID then it was not valid per point 1 and clients and servers cannot key on the ID (eg. for key mapped lists of IQs pending receipt or dispatch of a reply). An appropriate error or other behavior should be defined if the 'id' is meant to be REQUIRED, otherwise, if point 3 is correct, then 'id' should not be REQUIRED.

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