Subject: [sipcore] Model for manipulating hi-entries

From: "Elwell, John" <[email-masked]>
Date: Thu, 17 Feb 2011 22:28:44 +0100

In trying to review the rfc4244bis-03, I have tried to write down the model I have in my mind as to what we are trying to achieve at any of the entities involved (UAC, UAS, redirect, proxy). Based on what is in the draft and clarifications Mary has given in response to my comments, this is my current understanding:

1. Procedures for receiving a request
- Cache the sequence of entries received.
- If no entry or if last entry does not match Request-URI, create one and add it to the cache.

2. Procedures for sending a request
- Include all cached entries in the request.
- Generate an additional entry reflecting the Request-URI of the sent request, and add this to the request (but not the cache).
- In case of recursing, include in that new entry parameters from the Contact header field of the 3XX response.

3. Procedures for receiving a response (other than 100)
- Add to the cache the entry that was placed in the request and include in that cached entry a Reason header field containing the received response code (does this include 2xx too?).
- Add to the cache any entries in the response not already in the cache (i.e., any entries added by downstream entities).

4. Procedures for sending a response (other than 100)
- Include all cached entries.

All of the above subject to common rules relating to privacy, histinfo option tag, and indices.

John