SIP Common Gateway Interface

• Problem: Need low-level interface for creating SIP services.
• Solution: Derive interface from HTTP CGI; text-based way of sending requests to scripts, returning responses/actions.
• Status: Approved for Informational RFC.

SIP Register Payload

SIP Register Payload: Problem

• Want to be able to upload user control information (esp. SIP CGI and CPL scripts) to proxy servers.
• Also want to be able to download this information in the other direction, so you can edit it.
• Want it to be easy to associate this information with users with accounts at the proxy server.
• Want to make this lightweight -- your client shouldn't need to speak additional protocols or have too many new procedures.

SIP Register Payload: Solution

• Include the control information in the payload of REGISTER messages for the user.
• Indicate general "type" of control information in Content-Disposition headers. (Originally used Content-Type, but SIP-CGI scripts can be any media type.)
• Server returns currently registered scripts in body of 2xx REGISTER response.
• Script upload, download modified by Accept and Accept-Disposition headers.
• Special syntax for deleting scripts.
• Timestamps, If-Unmodified-Since (from HTTP 1.1) prevent race conditions when editing and re-uploading scripts.

SIP Register Payload: Example

   REGISTER sip:sip.example.com SIP/2.0
   From: Joe User 
   To: Joe User 
   Content-Type: application/x-perl
   Content-Disposition: sip-cgi; action=store
   Accept-Disposition: sip-cgi, cpl
   Accept: multipart/mixed, */*

   [body]

SIP Register Payload: Next Steps

• Some details still to work out, but I believe that the basic semantics are largely resolved. Can finish pretty easily.
• Already a number of implementations.
• I'd like this to be a SIP working-group item.
  (If the group weren't so overloaded...)
• Additional consideration: RFC 2183 requires that new Content-Disposition types be defined either in Standards Track or Experimental RFCs -- not Informational.