resource binding
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... session or send any XML stanzas.
2. Resource Binding -- after completing stream authentication, a
...
... Upon being so informed that session establishment is required (and
after completing resource binding), the client MUST establish a
session ...
... IM session upon successful authentication and resource
binding, which are performed simultaneously (documentation of this
protocol is contained in [JEP-0078], published by the Jabber Software
Foundation ...