DCON

DCON (Distributed CONferencing) is an actual implementation of a distributed web conferencing architecture we defined. It's compliant with the IP Multimedia Core Network Subsystem (IMS) specifiation and has been conceived to be highly reliable and scalable. Its name explicitly recalls the XCON model. DCON is in fact based on the idea that a distributed conference can be setup by appropriately orchestrating the operation of a set of XCON focus elements, each in charge of managing a certain number of participants distributed across a geographical network. At its current state, it is capable to provide to each focus the conferencing information about the remote "islands" recognized as "active" on the base of the user presence. The users can so join both local and remote conferences in a transparent fashion.
The system presented is intended to serve as a running experimental testbed useful for protocol testing, as well as field trials and experimentations.
 Such platform has been realized in the framework of a collaboration activity involving the University of Naples and Ericsson's Nomadic Lab in Helsinki starting from an Asterisk-based Confiance server.
We had to work both on the client and on the server side, as well as on the communication protocols between them. On the server side we implemented the discovery of remote foci and the spreading of the conference status information by means of the XMPP s2s channel. On the client side, we implemented the capability to interact with the DCON platform.
On the server side, we adopted Wildfire, an open source XMPP server. We added to Wildfire the following three new modules:

1. Conference Event Listener, used to intercept the conference events;
2. Focus Manager, used to manage remote focus presence information;
3. s2s Manager, which has in charge the spreading of conference events.

On the client side, instead, we adopted Spark, an open source XMPP client, which we made DCON-enabled and capable to schedulate new conferences and join existing ones by means of an ad hoc modified version of MjSip, a complete java-based implementation of a SIP stack. In such a way we provide an unified client for telephony and instant messaging.