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Presence

Presence. Vishal Kumar Singh and Henning Schulzrinne Feb 10, 2006. Bob is busy right now. He is on 42 nd ,Broadway . U can reach him after 4.00 p.m . on his office line. Bob’s Presentity. Presence System Overview. Presence Ability and willingness to communicate.

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Presence

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  1. Presence Vishal Kumar Singh and Henning Schulzrinne Feb 10, 2006

  2. Bob is busy right now. He is on 42nd ,Broadway. U can reach him after 4.00 p.m. on his office line. Bob’s Presentity Presence System Overview • Presence • Ability and willingness to communicate. • Rules about how and what part of presence info can be accessed • More detailed information includes location, preferred communication mode, current mood and activity • Presentity • Represents a user or a group of users or a program • Source of presence information • Watcher • Requester of presence information about a presentity

  3. Watchers Watchers Watchers Presentity and Watchers SUBSCRIBE Presence Server Bob’s Presentity PUBLISH NOTIFY Available, Busy, Somewhat available, Invisible Bob’s status, location Bob’s Filters (Rules), PIDF wife PUBLISH son R u there ? colleague BUZZ PC-IM Client Cell Phone external world Bob’s Presence User Agents (PUA)

  4. Presence System Components • Subscription • Subscribe to entities • Authentication of subscribers • Subscribers specify subscription rules • Notification • Updating presence state to watchers • Delivering presence data • Send notifications to the watcher in a scalable manner in real time • Lots of clients • Rate of change of data • Publication • Send information to the server for distribution. • Multiple sources for a single address • Updates communications means, and capabilities

  5. Presence Sources PSTN Phone, Cell Phone, VOIP Client candidate presence document privacy filtering Composition PUBLISH candidate presence document Composition Policy Presence Authorization Presentity specified filter NOTIFY Watchers final presence document filtered presence document Watcher Filter Post Processing Composition NOTIFY SUBSCRIBE specifies watcher filter NOTIFY Presence Data Processing

  6. Presence Authorization and Filtering • Presentities specify “block”, ”polite-block” or “allow” for the watchers • Presentities specify what presence information should be given to each watcher and when, in the presence authorization policy • Providing selective access to presence information • The rules can be based on time of day, location etc. and specify actions for different parts of presence information e.g. <provide-activities>

  7. SCP PSTN SIP PUBLISH SIP PUBLISH SIP PUBLISH Presence Server Presence Server Watchers/Buddies for one presentity Presence Server Presence Server Wireless Network Presence Server Watchers/Buddies for one presentity SIP Phone TV Cross-domain Presence Deployment SIP NOTIFY Presence Database SIP SUBSCRIBE IM Broadband IP Network (VoIP, Internet)

  8. Inter-domain presence: Cross federation (logical and physical) external-domain.com Logical and actual flow of messages being shown to domains that are logically or physically separated from an external domain SUBSCRIBE NOTIFY SUBSCRIBE NOTIFY SIP Proxy Server Presence Agent pa.columbia.edu Presence Agent pa.cs.columbia.edu PUBLISH Presence Agent pa.campus1.columbia.edu PUBLISH PUBLISH Logical sub-domain: cs.columbia.edu

  9. Presence Scalability Requirements • To make informed, accurate decisions, presence-based services depend on the timely delivery of presence information to watchers • Large number of watchers and presentities, with each presentity has many sources (PUA’s) • Every presentity’s status change may generate a NOTIFY to all watchers. • Load on the network

  10. SIMPLEStone • Benchmarking unit is a function of the supported user population • Can be expressed as the number of messages • rate of requests (PUBLISH, NOTIFY and SUBSCRIBE) • Number of messages per user depends on • Average number of user subscriptions (buddies) • Notification rate to the user from buddies. • Device mobility • Cellular or wifi phone • User behavior • TV as source of presence • IM user has his status as the internet radio • Number of sources

  11. SIMPLEStone – Factors Affecting Server Performance • Impact of composition policy • Single composition policy on server or per user composition. • Type of composition policies • Simple Union or Overriding • Intelligent Merge – Based on pivot element. • Rule based • Type of rule will effect the performance of server. Impact of Filtering • Privacy filter and watcher filtering • Larger filter => more look up, comparison and XML manipulation operations on the server • Impact on traffic generated by the presence server • Rate at which watcher modifies the filter

  12. Presence load generator. Models a user and generates PUBLISH at a specified rate User agent server. Models a user and generates SUBSCRIBE and receives NOTIFY messages. DB Handler (Watchers) PA Server Under Test Loader (Presentities) SUBSCRIBE PUBLISH 200 OK NOTIFY 200 OK 200 OK SIMPLEStone Architecture • The SUT can be replaced by different configurations in which the PA operates along with the SIP server. • The SUT details and other test details are specified using a configuration file to the test controller.

  13. SIMPLEStone SUT Configurations • SIMPLEStone sees different configurations of SUT as black box. • The database can be arranged into 2N or N+1 redundancy mode. • The Stateless proxy server(s) can act as load balancer distributing requests based on hashing algorithm. DB P1-PA DB s0 s0 DB P1-PA SIP Proxy Stateless Proxy P2- PA Configuration 2 Configuration 1

  14. Questions

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