Signaling, Media and Service--SIP and SOAP
By MortazaviBlog on Jan 18, 2005
It is tempting to integrate Session Initiation Protocol (SIP) with business transaction environment either through embedding XML based service control element in the message body of the SIP methods (e.g. INVITE, INFO, NOTIFY, etc.), or in the Session Description Protocol (SDP) part of the SIP INVITE method. However, these techniques are hardly ideal.
SIP was originally developed for the purpose of signaling, to be complemented with media transport protocols, say RTP, for VoIP applications. As SIP began to be used for messaging, authentication, presence, group services, etc., some started to use the direct methods for extending it in order to integrate SIP user agents within service environments. (In fact, I myself am guilty of a bit of this, too, dreaming up a way to play a multi-player, asynchronous games, using SIP as some kind of media transport and service control protocol.)
A possibly better approach is to develop a SOAP interface for use by SIP user agents and service control endpoints. In other words, every UA node exporting a SIP endpoint can also export a SOAP endpoint for integration within the service environment. In this way, some inappropriate extensions may be possible to avoid.