Using Presence Information to Develop Converged Telecom Services

1
Using Presence Information to Develop Converged
Telecom Services

• Standards and Challenges

Parijat Garg Computer Science, IIT Bombay
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Outline

• Presence Overview
• Presence Data Model
• Filtering Presence Information
• Subscribing to Dynamic Presence
• Challenges
• Conclusions

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What is Presence Information

• Offline and online presence
• Multiple points of availability
• Status of availability on each medium
• Physical location

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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

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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 hes 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

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The Presence Architecture
Uses presence information (e.g., application)
Watcher
Watcher
Watcher
Presence Server
Aggregates presence information. One presence
doc. per user
Generates presence information (e.g., mobile
phone)
Presentity
Presentity
Presentity
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Outline

• Presence Overview
• Presence Data Model
• Filtering Presence Information
• Subscribing to Dynamic Presence
• Challenges
• Conclusions

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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
ltpresence entitypresbob_at_somewhere.comgt lttuple
iddevIM01gt ltstatusgt ltbasicgtopenlt/basicgt
lt/statusgt ltcontact priority0.76gt IMbob_at_s
omewhere.com lt/contactgt lt/tuplegt lt/presencegt
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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

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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

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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

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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

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Outline

• Presence Overview
• Presence Data Model
• Filtering Presence Information
• Subscribing to Dynamic Presence
• Challenges
• Conclusions

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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

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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

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Outline

• Presence Overview
• Presence Data Model
• Filtering Presence Information
• Subscribing to Dynamic Presence
• Challenges
• Conclusion

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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

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Questions?
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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