If any action fails, the component returns it with sm:failed='1' on the
session element. We don't use the route type at all anymore, that is
reserved for _routing_ errors. This has the nice side effect of allowing
us to distinguish between "session ended" and "sm crashed".

No bounce must result from a failed action.

The namespace URL is "http://jabberd.jabberstudio.org/ns/session/1.0"


c2s->sm: start session

  <route to='cataclysm.cx' from='c2s'>
    <sm:session xmlns:sm='[url]' sm:c2s='5' action='start' target='rob@cataclysm.cx/enigma' id='123456'/>
  </route>

sm->c2s: session started

  <route to='c2s' from='cataclysm.cx'>
    <sm:session xmlns:sm='[url]' sm:c2s='5' sm:sm='2' action='started' target='rob@cataclysm.cx/enigma' id='123456'/>
  </route>


c2s->sm: end session

  <route to='cataclysm.cx' from='c2s'>
    <sm:session xmlns:sm='[url]' sm:c2s='5' sm:sm='2' action='end'/>
  </route>

sm->c2s: session ended

  <route to='c2s' from='cataclysm.cx'>
    <sm:session xmlns:sm='[url]' sm:c2s='5' sm:sm='2' action='ended'/>
  </route>


c2s->sm: send packet

  <route to='cataclysm.cx' from='c2s'>
    <message to='foo@jabber.org' xmlns:sm='[url] sm:c2s='5' sm:sm='2'>
      ...
    </message>
  </route>

sm->c2s: send packet

  <route to='c2s' from='cataclysm.cx'>
    <message from='foo@jabber.org' xmlns:sm='[url] sm:c2s='5' sm:sm='2'>
      ...
    </message>
  </route>


c2s->sm: create user

  <route to='c2s' from='cataclysm.cx'>
    <sm:sessions xmlns:sm='[url]' sm:c2s='5' action='create' target='rob@cataclysm.cx' id='123456'/>
  </route>

sm->c2s: user created

  <route to='c2s' from='cataclysm.cx'>
    <sm:sessions xmlns:sm='[url]' sm:c2s='5' action='created' target='rob@cataclysm.cx' id='123456'/>
  </route>


c2s->sm: delete user

  <route to='c2s' from='cataclysm.cx'>
    <sm:sessions xmlns:sm='[url]' action='delete' target='rob@cataclysm.cx'/>
  </route>

sm->c2s: user deleteed

  <route to='c2s' from='cataclysm.cx'>
    <sm:sessions xmlns:sm='[url]' action='deleted' target='rob@cataclysm.cx'/>
  </route>