SIP SIMPLE Client SDK

= Presence Blueprint =

[[TOC(DesignBuddyList, depth=2)]]

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 presence event package, 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.

To build this consolidated list, a SIP client supporting multiple SIP accounts must perform for each account the steps from the ''Account'' section by accessing local or remote ''Storage'' used for each SIP account.

Each individual list 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). 

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 build 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 is stored on exactly one XCAP server to provide atomic transaction. 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.

Each Contact can belong to a single Group. The SIP client maintains a central ''Groups List'' by merging all found Groups on all local and remote storages and will populate each Group with all recipients found for them.

[[Image(BuddyList-Aggregation.png)]]

== Account ==

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

== 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