The SIP Servlet API provides a model for application composition and interaction. Service Interaction which is analogous with a simplistic implementation of the Service Capability Interaction Manager (SCIM) alluded to by the 3GPP. Handling of all incoming requests is governed by the Converged Application Server SIP Servlet Container in accordance with the SIP Servlet API specification.

Oracle Communications Converged Application Server's SIP Servlet Container filters received Initial SIP requests and applies a set of defined rules (Servlet Mapping Rules) to determine which SIP Servlets within the deployed applications shall be invoked to service that particular request. This order is always sequential and is defined in a configuration file built up through successive deployments of SIP applications.

Within the deployment descriptor for each SIP application that is deployed, a sequence of conditions, called Servlet Mapping Rules, is defined. These rules determine which Servlets will handle any initial request. As the request object is "routed" between Servlets, the path from Servlet to Servlet is recorded in a fashion equivalent to that of the Record-Route and Via headers used in SIP requests. This route is stored as part of the SIP application session and is appended to subsequent requests within the same dialogue in either "forward" or "reverse" order depending on the orientation of the “From" and “To" tags for the request. This internal "route" is stripped from the request object before a SIP request leaves Converged Application Server and is not visible to external SIP servers. It is again added whenever a new request within an existing dialog is received.

The SIP Servlets (SIP/HTTP application) that are invoked in this manner are unaware that any other SIP/HTTP application exists. This is one of the fundamental characteristics of the SIP Servlet programming model. Making maximal use of this model requires that the Servlet container be treated by the developer as if it is a logical sub-network, with the container effectively acting as an intermediary proxy. In many ways, the SIP Servlet Container may be compared with the Serving CSCF function in an IMS architecture.