Timers and Scheduling

Timers and scheduling are integral to SIP application development, enabling reliable handling of time-dependent operations such as managing timeouts, resending SIP messages, or cleaning up inactive sessions. These capabilities are important in SIP, where adherence to timing protocols, such as those outlined in RFC 4028 for session timers, is critical for maintaining session integrity and service reliability.

The SIP Servlet API provides a timer service, a container-managed feature that allows applications to schedule timers and receive notifications upon their expiration. Timers are treated as managed resources by the container, and for enhanced reliability, they can be made persistent—stored alongside session data to survive server restarts.