System information

wide area networks, we can now have Asterisk systems at different physical locations
distribute device state information to each other (see Figure 22-7). With the OpenAIS
implementation, the library would be used on each system, enabling them to distribute
device state information. In the XMPP scenario, a central server (or cluster of servers)
is used to distribute the state among all of the Asterisk boxes in the cluster. Currently
the best application for doing this is the Tigase XMPP server (http://www.tigase.org),
because of its support for PubSub events. While other XMPP servers may be supported
in the future, only Tigase is known to work at this time.
Figure 22-7. Device state distribution with XMPP
With XMPP, the queues can be located in different physical locations, and satellite
offices can take calls from the primary office, or vice versa. This provides another layer
of redundancy, because if the primary site goes offline and the ITSP is set up in such a
way as to fail over to another office, the calls can be distributed among those satellite
offices until the primary site goes back online. This is quite exciting for many people,
as it adds a layer of functionality that was not previously available, and most of it can
be done with relatively minimal configuration.
498 | Chapter 22: Clustering