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One of Cipango goals is to be able to host a variety of SIP elements (stateful, stateless. ..). To support this goal, the SIP layer is organized as a pipeline of handlers. The first handler to be called after a message has been received is the Server which then delegates the actual processing to a configured chain of handlers. Depending on how this chain is configured, Cipango may run a variety of SIP elements, from stateless proxies to fully stateful SIP Servlets engine.
The architecture of Cipango configured as a Servlet engine is represented on the following figure:
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