SIP SIMPLE Client SDK

= Presence Blueprint =

<abbr title="DesignBuddyList, depth=2">TOC</abbr>

This is a High Level representation of a mechanism that maintains a ''Contacts List'' and handles Subscriptions, Publications and Notifications that can be used by a ''SIP client'' with a graphical user interface. It implements a combination of SIP SIMPLE standards related to event packages like presence, storage and policy.

Contacts List

''Contacts List'' contains is a list of contacts displayed by the GUI. It must be managed by the SIP client at a global level above the individual SIP account level.

The ''Contacts List'' is organized in ''Groups''. Each Contact belongs to a single Group and the Groups are unique. The SIP client maintains this central ''Groups List'' by merging all found Groups on all local and remote storages and populates each Group with all recipients found for them.

Some contacts are marked for Subscribing to them for ''Presence'' information. Based on received Notify messages for ''Event: presence'', each Contact has a ''presentity'' attribute that contains its own published information as pidf xml payload, the GUI display attributes of it. Each contact can also publish properties related to his device capabilities (e.g. can_chat, can_share, can_talk, can_video). This is conveyed via ''caps'' extensions to ''pidf'' and can be used to drive the contextual menus for each Contact related to what kind of action can be initiated to them.

=== Storage ===

The ''SIP client'' builds the ''Contacts List'' by concatenating the individual lists stored locally or on the ''resource-lists'' documents stored on the XCAP server corespondent to each SIP account. A Contact can be stored on a single XCAP server in order to have atomic changes. When a Contact is added/modified/deleted the corespondent remote XCAP storage is updated. The remote storage is set per Contact in the Add/Edit Contact dialog of the SIP client.

Image(BuddyList-Aggregation.png)

Account

Each SIP Account has settings that affect the way it stores the ''Contacts List'' and how it interacts with its correspondent Contacts.

On boot:

If ''account.xcap'' is enabled

• If ''account.xcap.xcap_root'' is not set, locate XCAP root by doing a DNS TXT lookup for xcap.example.com
• GET XCAP application xcap-caps
• GET XCAP application xcap-directory
• For all supported applications returned by above step, GET their files and cache them locally
• If ''account.xcap.subscribe_xcap_diff'' is enabled, sent Subscribe for ''Event: xcap-diff''
• if ''Icon'' application is enabled, GET the previous icon using HTTP request

If ''account.presence.enable_publish'' is enabled

• If ''pidf-manipulation'' application is supported by the XCAP server, update the pidf with its content and update GUI with the fact that we have server based PIDF set
• Send Publish with the current pidf if pidf_manipulation is not set, let the user change his state manually if pidf_manipulation is set

If ''account.presence.subscribe_winfo'' is enabled

• Send Subscribe for ''presence.winfo''
• Initialize ''Watchers List'' for ''Event: presence'' based on received Notify

If ''account.presence.resource_lists'' is enabled

• Initialize the ''Contacts List'' by using the content of the XCAP document ''resource-lists'', filename ''index''. Initialize the ''Subscriptions List'' using the Contacts marked for ''Subscribe to Presence''

If ''account.presence.rls_services'' is enabled

• Put the content of ''Subscription List'' initialized above to the XCAP document ''rls-services'' identified by SIP URI account-buddies@domain

If ''account.presence.subscribe_presence'' is enabled

• If ''account.presence.subscribe_rls_services'' is True send one Subscribe for ''Event: presence'', and header ''Supported: eventlist'' to account-buddies@domain
• Else for each contact in the ''Contacts Lists'' send Subscribe for ''Event: presence''

While running:

• Refresh the XCAP server location based on DNS TTL
• Reload changed XCAP documents based on ''Event: xcap-diff'' Notifies

Each individual contact list stored in a resource-lists document is indexed by a unique SIP URI, a random SIP URI must be generated for Contacts that do not have a real SIP URI and we must mark the contacts that we want to Subscribe to for presence information. Additional, one can store full names and other attributes related to remote recipient by using extensions to PIDF for contact information (cipid extension).

Policy change * Based on Notify for ''Event: presence.winfo'' alert the user about new watchers and update the policy stored in the pres-rules XCAP document * PUT ''pres-rules'' document on the XCAP server

Transformations are required to support the following functionality:

1.  First degree watchers - access to entire PIDF
 1.  Second degree watchers - access to subset of PIDF
 1.  Third degree watchers - access to basic presence online/offline

Icon change

OMA has specified the use of XCAP server for icon application [http://www.openmobilealliance.org/technical/release_program/docs/PresenceSIMPLE/V2_0-20081223-C/OMA-TS-Presence_SIMPLE_Content_XDM-V1_0-20081223-C.pdf Presence Content XDM Specification]

Publishing end-point:

1. Generate a new random filename: XYZ
 1. Build URL http://xcap.example.com/xcap-root/org.openmobilealliance.pres-content/users/sip:alice@example.com/oma_status-icon/XYZ
 1. PUT the new icon document to XCAP server
 1. Update <icon> element of pidf and PUBLISH new pidf
 1. DELETE any previously uploaded icon file

Subscribing end-point:

1. Parse <icon> element of pidf cipid extension received in Notify
 2. HTTP GET http://xcap.example.com/xcap-root/org.openmobilealliance.pres-content/users/sip:alice@example.com/oma_status-icon/XYZ
 3. Cache picture until next Notify with diferent <icon> element is received