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

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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)

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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.

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SIP/SIMPLE Presence Data Model

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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

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Sample PIDF Document

<presence entity=“pres:bob@somewhere.com”>

<tuple id=“devIM01”>

<status>

<basic>open</basic>

</status>

<contact priority=“0.76”>

IM:bob@somewhere.com

</contact>

</tuple>

</presence>

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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

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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)

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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

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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

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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

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Filtering Presence Information

GEOPRIV specifies transformations for obfuscating location information

Civil location can be obfuscated to various levels – country, state, district, etc

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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

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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

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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

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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

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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

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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

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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