1. Slide #1 URI List Index Lucent Technologies Tom Hiller Dean Willis Adam Roach

2. Slide #2 Background SIPPING has chartered work to specify how SIP uses URI lists URI lists can be stored on servers and referenced via a URI. This usage is called a server-stored list. URI lists can be contained in a request. This usage is called a request-contained list. Usage of both types of list is being defined for each request type. Server-stored lists can be arbitrarily long. We want to be able to have a request apply to a specific subset of the members of a list, with the subset indicated in the request. We want this subsetting operation to be extremely concise. This would make it very useful for mobile scenarios, especially Push to Talk.

3. Slide #3 Use Case Bob has a server-stored list which contains URIs for every member of his athletic club Bob wishes to invite three specific members (Bill, Joe, Alice) of his club to participate in a conference call. Bob constructs a SIP request that references the server-stored list and includes selection criteria for the three specific members. Bob request-handling server extracts the URIs for Bill, Joe, and Alice from Bobs list and sends the request to them. They chat.

4. Slide #4 Proposed Mechanism Extend resource list XML schema to include key values (membercodes) for each member Define new MIME types to include a list reference and a set of key values Use new MIME type as a cid: body in a request, as request-contained usage does. The request-handling application retrieves list and applies membercodes to select intended target set.

5. Slide #5 Proposed MIME Types application/resource-lists-indices Only a few member of a relatively large list are included in the SIP request. Applies best for a sparse subset of the list. This MIME is just a list of membercodes application/resource-lists-bitmap Many or most of the members of a list are included in the SIP request. Applies best for a relatively dense subset of the list. This MIME is a binary array represented as hex digits. A bit in the array being set implies the member code of that value is included. Groups of four bits represent hex digits.

6. Slide #6 Example Resource List with Membercode

7. Slide #7 Examples application/resource-lists-indices Bob wishes to identify Bill in a SIP request. The MIME body based on the previous slide is: athletic-club 2 application/resource-lists-bitmap Bob wishes to identify many club members in a SIP request; the membercodes of the individuals are 2, 4, 5, 9, 19, 25, 36. The MIME body might be: athletic-club 010110001000000000100001000000000010000 Or, as per current draft, something like athletic-club A13BD

8. Slide #8 Issues and Further Steps Specific MIME format to use Addition of membercodes to resource list schema Requires modifying the schema to allow the addition of attributes Membercodes must be unique; this requires XCAP handling for validation. (server rejects non-unique write attempts with suggestions) Client offers a membercode, the server validates, possibly rejecting with suggested codes on failure while reserving suggested membercodes briefly Do we enumerate across embedded list members? Tentative direction: modify the schema to permit the addition of attributes. Progress this draft separately.