[SIP Beyond VoIP] Presence using RLS support in upcoming Blink release
ag at ag-projects.com
Fri Sep 21 13:18:46 CEST 2012
Here is some technical information about the support for Presence in upcoming Blink release. This is work in progress and if you have comments or suggestions you may attach them to the link below:
This functionality will be available in upcoming Blink Pro 2.0 and Blink Lite 2.0 for MacOSX and also on Blink-Qt for Window and Linux.
Blink should work with any SIP and XCAP servers that supports all related SIP SIMPLE standards, but only a subset of them are used. They are described below:
Blink uses only TCP or TLS transports for signaling
Blink presence payload is based on RPID schema with its extensions for media capabilities and person information
Blink relies on a Presence Agent collocated with the SIP Registrar that supports PUBLISH method and XCAP storage
Presence Agent must support handling of presence rules using org.openmobilealliance.pres-rules XCAP document
Presence Agent must support external references from rls-services to resource-lists
Presence Agent must support external references from rls-services to org.openmobilealliance.pres-rules
Presence Agent must support presence and presence.winfo event packages
Presence Agent may support xcap-diff event package for XCAP documents replication between clients
Presence Agent must support RLS subscriptions and RLMI notifications
SIP Registrar may support GRUU
XCAP server may support serving the user icon from org.openmobilealliance.pres-content document
XCAP server must support the following XCAP applications: rls-services, resource-lists, xcap-caps, org.openmobilealliance.pres-content, org.openmobilealliance.pres-rules, org.openmobilealliance.xcap-directory
XCAP server may support pidf-manipulation for offline status
There is no guaranty Blink Presence functionality would interoperate with other SIP clients due to the freedom allowed by the standards in modeling the data used for contacts storage.
Presence is a complex issue and the mechanisms used internally by Blink may not necessarily work under your own server environment. If you want to troubleshot when things do not work as expected, first use the built-in Blink accounts that are designed to work with SIP2SIP domain. As protocol traces for signaling and storage are logged to file, you can easily access such debug information and analyze Blink behavior.
We can provide support, if you encounter interoperability issues with any the following products and services against which Blink has been fully tested:
SIP2SIP.info (a public free SIP service)
Interoperability with XMPP domains (using SylkServer SIP/XMPP gateway)
OpenSIPS/OpenXCAP combination (server software you can run on your premisses)
There is nothing that should prevent Blink interoperate with any other SIP end-points as far as SIP signaling is concerned (PUBLISH, SUBSCRIBE and NOTIFY methods). Blink will preserve contacts related information it did not create in XCAP documents. Unfortunately, we have not found other clients that behave in the same way. Sharing the same XCAP documents with other SIP clients is therefore strongly discouraged as is guaranteed to cause failures.
You can also enable one SIP2SIP account in your Blink instance to perform presence and contact storage operations while using your preferred SIP provider to make phone calls.
As presence require proper infrastructure that many SIP service providers simply lack today, do not complain to us when Presence does not work with your SIP service provider.
Contacts are stored on the XCAP server in the resource-lists document under a proprietary name space to avoid conflicts with other end-points that might use the same document as there is no common standard way for how to store a rich address book on a server. This means that different SIP user agents from different vendors cannot read or modify this data in a deterministic way. The contacts in the address-book are then used by standard OMA rls-services and pres-rules XCAP documents. Contacts have two Presence related properties that can changed in Edit Contact Panel Subscriptions section:
Subscribe to Contact's Presence Information
Allow Contact to see my Presence Information
If an URI part of the contact is labelled as XMPP, when using a SIP2SIP.info account the session request will be forwarded to an XMPP gateway.
Using SUBSCRIBE for presence.winfo event package, Blink keeps track of presence watchers and their status.
Contacts that have subscribed to our presence are rendered in the 'New Contact Requests' group that is rendered on top of the contacts list. Right click or dragging the contact can be used to allow or deny the request. Blocked contacts are displayed in the Blocked group.
Active watchers are shown in Status -> People Watching My Presence Activity menu
Using PUBLISH method for presence event package, the following information is published by Blink:
Open or closed.
Blink uses a proprietary extension for indicating the extented status compatible with XMPP end-points.
Location is based on CIPID map extension. Location can be disabled per account in Presence section of account preferences.
A home page can be entered in Presence section of account preferences. Homepage is based on CIPID homepage extension.
Presence note can be typed in the text area right to own icon in the main GUI window. Note is attached to the service.
Presence status can be changed from the main GUI window and Status menu. Last combination of Presence state and note are saved in the history build at the end of the menu.
User icon is uploaded to XCAP server using OMA pres-content application, replicated among multiple Blink instances and location of icons storage URL on XCAP server is published in PIDF.
In status menu, one can change its presence state and also an offline state when Blink is offline. This is done using pidf-manipulation XCAP application.
Type of media supported by the end-point.
The following information is published:
GRUU contact address
<presence xmlns="urn:ietf:params:xml:ns:pidf" entity="sip:ag at test.sip2sip.info">
<tuple xmlns="urn:ietf:params:xml:ns:pidf" xmlns:agp-pidf="urn:ag-projects:xml:ns:pidf" xmlns:c="urn:ietf:params:xml:ns:pidf:cipid" xmlns:caps="urn:ietf:params:xml:ns:pidf:caps" xmlns:agp-caps="urn:ag-projects:xml:ns:pidf:caps" xmlns:rpid="urn:ietf:params:xml:ns:pidf:rpid" xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model" id="SID-f4649f87-1aa3-44ec-ab49-d0464528d706">
<agp-pidf:user-agent>Blink Pro 2.0.0 (MacOSX)</agp-pidf:user-agent>
<dm:person xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model" xmlns:rpid="urn:ietf:params:xml:ns:pidf:rpid" id="PID-5c82e1b170c9aa1a670c4388052657f2">
<dm:device xmlns:dm="urn:ietf:params:xml:ns:pidf:data-model" id="DID-f4649f87-1aa3-44ec-ab49-d0464528d706">
<dm:note>Blink Pro 2.0.0 (MacOSX) at imac3-2</dm:note>
Subscribe To Presence
Using SIP SUBSCRIBE for RLS, Bink subscribes to the SIP addresses stored in rls-services document uploaded on the XCAP server by contacts management actions in the GUI (add/update/delete contacts).
Presence information received from the SIP URIs as RLMI notifications from the RLS server is used to update each contact in the contacts list with:
Icon is fetched from the icon URL published by the user
Status icon overlaid on botton right of user icon, indicating away, busy, extended-away or available
Rectangular presence indicator on right side of the tile to provide a quick overview about availability
Presence note is rendered on second line, multiple notes and pending authorizations are rotated every 10 seconds
User icon is retrieved and updated when necessary from URL advertised by user
Selecting Show Presence Information menu item from contextual contact menu show a panel with detailed information, not all information may have been rendered in the GUI.
When subscribed to Presence, if information is received, the contextual menu of each contact is updated with the possibility of starting a session to a specific device if the remote server and device uses GRUU.
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