Using Presence Information to Develop Converged Telecom Services Standards and Challenges Parijat...
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Transcript of Using Presence Information to Develop Converged Telecom Services Standards and Challenges Parijat...
Using Presence Information to Develop Converged Telecom Services
Standards and Challenges
Parijat Garg
Computer Science, IIT Bombay
Dec. 2005 2
Outline
Presence Overview Presence Data Model Filtering Presence Information Subscribing to Dynamic Presence Challenges Conclusions
Dec. 2005 3
What is Presence Information
Offline and online presence Multiple points of availability Status of availability on each medium Physical location
Dec. 2005 4
Converged Telecom Services
Communication meant for person-to-person contact
Users should have a uniform interface facing them, irrespective of differences in underlying networks
Convergence is about moving from device-to-device communication to person-to-person communication
Dec. 2005 5
Using Presence Information
Consider the life of Stephen Smith busy executive offices in multiple locations (hence needs to
commute often) Commuting to office
Barrista knows he’s on the way; keeps coffee ready During office hours
Drives into office and logs into instant messaging service
Service center redirects all calls to office wire-line phone
Friends’ calls redirected to voice-mail When in meeting, status determined using
scheduler; All calls diverted to voice-mail
Dec. 2005 6
Using Presence Information (contd.)
Traveling to another location during lunch Moving out of office, Instant Messenger status set to
away While driving, phone status set to “in-transit” For lunch, nearby open restaurants displayed
automatically
Dec. 2005 7
The Presence Architecture
Presence Server
Presentity Presentity Presentity
Watcher Watcher Watcher
Generates presence information (e.g., mobile phone)
Aggregates presence information. One presence doc. per user
Uses presence information (e.g., application)
Dec. 2005 8
Outline
Presence Overview Presence Data Model Filtering Presence Information Subscribing to Dynamic Presence Challenges Conclusions
Dec. 2005 9
Conveying Presence
Multiple protocols defined, each with associated payload formats
SIP/SIMPLE, XMPP, … SIP/SIMPLE being adopted in the telecom world
SIP for Instant Messaging and Presence Leveraging Extensions (IETF working group)
Defines SIP (with extensions) as the protocol PUBLISH, SUBSCRIBE, NOTIFY
Notion of event packages Presence event package defined
Base payload format defined Presence Information Data Format (PIDF) Several extensions available
E.g., RPID, CIPID, Geopriv, etc.
Dec. 2005 10
SIP/SIMPLE Presence Data Model
Dec. 2005 11
Conveying Presence [PIDF]
Limited information conveyed in PIDF For each service, it presents
status tag for availability (open/close) contact tag for address (can be IM, tel, etc) note tag for human readable comment timestamp tag for time when presence information
was published All SIP/SIMPLE compliant services must support
PIDF
Dec. 2005 12
Sample PIDF Document
<presence entity=“pres:[email protected]”>
<tuple id=“devIM01”>
<status>
<basic>open</basic>
</status>
<contact priority=“0.76”>
</contact>
</tuple>
</presence>
Dec. 2005 13
Conveying Presence [RPID]
Rich Presence Extensions to PIDF Adds a person and device tag activity, mood, sphere, place-type etc
information about person relationship and privacy tag for tuples
Dec. 2005 14
Conveying Presence [GEOPRIV-LO]
Adds fine-grained location information to base PIDF
Location specified using Geographic Markup Language (GML)
Extends status tag to add geopriv tag location-info under geopriv usage-rules under geopriv
Dec. 2005 15
Conveying Partial Presence
Entire presence document may be large Facility to updates parts of the document Specially useful in low-bandwidth
environments (such as cellular networks)
Dec. 2005 16
Outline
Presence Overview Presence Data Model Filtering Presence Information Subscribing to Dynamic Presence Challenges Conclusions
Dec. 2005 17
Filtering Presence Information
User may not want everyone to see his presence
Might want to conceal more or less information from different users
XML-based language for fine-grained access control
Dec. 2005 18
Filtering Presence Information
Notion of ruleset and rules Each rule conditionally allows more and more
access to presence information A rule has three parts
Conditions Transformations Actions
Dec. 2005 19
Filtering Presence Information
Conditions specify situations in which rule is applicable
Three basic conditions Identity – the identity of the requestor Sphere – the situation in which the user is in
(work/leisure/etc). Validity – A time duration during which rule will be
applicable Extensions can be defined
Dec. 2005 20
Filtering Presence Information
Transformations specify the filtering operations to be applied to presence document
Different parts of document can be made available, based on device-id, etc
provide-person and provide-service allow providing access to person and tuple elements of presence document
Dec. 2005 21
Filtering Presence Information
GEOPRIV specifies transformations for obfuscating location information
Civil location can be obfuscated to various levels – country, state, district, etc
Dec. 2005 22
Filtering Presence Information
Actions do not modify the presence document. They specify actions to be taken by presence server.
Can be used to handle subscriptions – like block, allow, confirm with user, polite-block, etc
Dec. 2005 23
Outline
Presence Overview Presence Data Model Filtering Presence Information Subscribing to Dynamic Presence Challenges Conclusions
Dec. 2005 24
Subscribing to Presence Information
Continuous delivery of presence information not desirable
Event-based subscription mechanism required Notion of filter-set is defined Each filter-set has several filter elements
Dec. 2005 25
Subscribing to Presence Information
Filter tag contains two elements What – declares what element of presence information is
desired Trigger – declares the conditions under which a notification
is sent to the subscriber
Dec. 2005 26
Subscribing to Presence Information
The What element can either be used to include or exclude some part of a presence document
The elements to include/exclude can be specified using an XPath expression or using a namespace specification
Dec. 2005 27
Subscribing to Presence Information
The trigger element can consist of one or more of the following tags
Changed – specifies that a notification should be raised if value of a particular element changes
Added – when a new element is added to presence document
Removed – when an element is removed from the presence document
Dec. 2005 28
Subscribing to Presence Information
The changed element can have three attributes from – specifies that a notification is triggered if specific
element in presence document changes from a particular value to something else
to – raises notification when value changes to this value by – specifies the delta by which value should change to
trigger a notification
Dec. 2005 29
Outline
Presence Overview Presence Data Model Filtering Presence Information Subscribing to Dynamic Presence Challenges Conclusion
Dec. 2005 30
Challenges
Multiple documents involved in subscription handling e.g. – “notify me when my wife is within 5 miles of
me” – requires comparing two presence documents e.g. – “show me all my friends in leisure” – requires
several documents including a buddy list Language required to specify documents to be
referred
Dec. 2005 31
Challenges
“changed by” triggers may require multiple copies of same presence documents
Triggers are evaluated on filtered documents – may mean continuous filtering of documents per user per subscriber
Scale of operation can be very large. 55 million mobile phone subscribers in India. Similar figure for land-lines.
Identity management
Dec. 2005 32
Outline
Presence Overview Presence Data Model Filtering Presence Information Subscribing to Dynamic Presence Challenges Conclusion
Dec. 2005 33
Conclusion
Telecom and communication networks are maturing to the next level
Convergence is the next big thing Standards need to be developed and adopted Scales of operations are large and systems need to
be able to handle that
Dec. 2005 34
Questions?
Dec. 2005 35
Slides of the talk can be found at:
http://www.cse.iitb.ac.in/~parijat/comad2005b.php
Errata:
Ref 14 : RFC 3265: Session Initiation Protocol (SIP) – Specific Event Notification