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

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.

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.

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.

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.

Slide #6 Example Resource List with Membercode

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 Or, as per current draft, something like athletic-club A13BD

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.