Programmable Active Services for SIP

SIP-based IP telephony offers the promise of rapid service creation and dynamic deployment. SIP services are fragments of code that are triggered by SIP messages and can perform actions on behalf of registered users. We present programmable active services for SIP (PASS), a technique that uses Java security and Java bytecode re-writing to allow un-trusted services to run on SIP signaling servers. Our technique allows users to write and upload services as Java classes with no a priori constraints on the structure or content of the programs. This generality permits users to leverage the extensive Java libraries and to program new SIP services in familiar environments. We define an extended, SIP specific, Java security model that restricts the behavior of the executing SIP service and that constrains the computational resources that it consumes