||This is called whenever a new client connects. It is not
necessarily a client that is subscribing to one of the publisher's
||This is called when a newly connected client is resolved. A
client's full geographical information is not necessarily available
as soon as a client connects and so this method is called separately
after the client has been resolved.
||This is called whenever a client attempts to subscribe to a topic
that does not exist. This might be because the topic is not yet
available and this gives a publisher the opportunity to create the
topic and subscribe the client to it.
||This is called whenever a client attempts to fetch a topic that
does not exist. This gives the publisher the opportunity to respond
to fetch request on a non-existent topic. A publisher can even reply
to such a request without having to create a topic using the
||This is called whenever a client attempts to send a message to a
topic that does not exist, or to which the client is not subscribed.
This enables a client to send a message to a topic and for that
topic to be created and subscribed to on demand, or send data when a
response is never expected.
||This is called whenever a client's queue breaches an upper queue
notification threshold or returns to a lower queue notification
threshold. Parameters indicate which threshold has been reached and
the threshold value.
||This is called whenever a client supplies new credentials after
connection. It is called after the authentication handlers have
validated the credentials.
||This is called whenever a client disconnects. The reason for
disconnection can be obtained using