1. A Gateway For SIP Event Interworking - Sasu Tarkoma & Thalainayar Balasubramanian Ramya

2. MOTIVATION Interworking of SIP event framework with the generic publish/subscribe system SIP Event Framework does not support anonymous one-to-many event dissemination Challenges: SIP Event Framework does not support expressive filtering Proposed Solution: Implementation of a gateway component enabling interworking between the SIP event framework, and publish/subscribe system Application of the proposed Gateway: Universal Data Access

3. BACKGROUND INFORMATION Session Initiation Protocol (SIP) : a standard, text-based, application layer, signaling protocol developed by the Internet Engineering Task Force (IETF). Described in RFC 3261 Purpose of SIP: To establish, modify and terminate multimedia sessions over the IP network Acceptance as standard: Selected by the 3 rd Generation Partnership Project (3GPP), as the session establishment protocol for the 3GPP IP Multimedia Core Network Subsystem (IMS)

4. SIP Application Areas: Internet Telephony Control Applications E-Commerce Multimedia Conferences Instant Messaging BACKGROUND INFORMATION

5. SUBSCRIBE NOTIFY 200 SIP EVENT FRAMEWORK SIP Event Framework: An extension of Session Initiation Protocol, described in RFC 3265 Methods supported: SUBSCRIBE, NOTIFY Fig 1. SIP Event Subscription and Notification SUBSCRIBERNOTIFIER

6. Forward subscription to notifier proxy SIP Proxy 1 (Redirect mode) DNS DNS lookup SIP Proxy 2 (Redirect mode) UAC 3 Forward request to notifier Update location server Notification response to proxy Forward SUBSCRIBE RegistrarLocation Server UAC 1 UAC 2 register Forward notification to subscriber Proxy query Forward notification to subscriber proxy Forward SUBSCRIBE to notifier Forward notification to notifier proxy SIP DOMAIN Fig 2. Working of SIP Domain

7. COMPONENTS IN SIP DOMAIN SIP Proxy: Receives SIP requests/responses from clients/ proxies, processes, and forwards it to the next hop or final destination SIP Client: Receives/Sends SIP requests/responses Location Server: Stores updated client information Redirect Server (Redirect Mode): Provides the contacted client’s current address to the contacting client Registrar: Maintains registered clients information, queries and gets recent updates from Location Server

8. APPLICATION AREAS OF CONTENT BASED PUB/SUB EVENT MODEL Active Badge Systems Proximity Sensors Information and Multimedia Delivery Services Positioning Systems

9. P1P1 P2P2 PnPn S1S1 S2S2 SnSn Subscribe() Unsubscribe() Publish() Publish Unsubscribe Subscribe WORKING OF PUBLISH/SUBSCRIBE EVENT MODEL Fig 3. Publish/Subscribe Event model Event Service PublishersConsumers

10. Gateway SIP Domain Pub/Sub Domain I O I O Conversion, Mapping, State GATEWAY DESIGN Fig 4. Gateway Design

11. NIST-SIP STACK JAIN-SIP Proxy SIP clients Fuego Event Service Fuego Clients GATEWAYGATEWAY subscribe/ publish subscribe/ notify IMPLEMENTATION ARCHITECTURE Fig 5. Implementation Architecture

12. GATEWAY FUNCTIONALITIES Receive SIP messages (requests/responses) Convert SIP message to pub/sub messages. Forward the converted messages to Fuego domain Receive pub/sub messages Convert pub/sub messages to SIP messages (requests/ responses). Forward the converted messages to the SIP domain Associate the received messages using unique identifiers. Call Identifier of the SIP and subscription identifier of the Fuego message are used for association. Generate and send SIP provisional responses to the SIP domain

13. SIP DOMAIN SUBSCRIBE Forward SUBSCRIBE Process subscription Subscription status Forward SIP response PUBLISH Forward NOTIFY OK Mapping, reformat SUBSCRIBE Create SIP response Mapping, reformat PUBLISH GATEWAYFUEGO SYSTEM SIP AND FUEGO SUBSCRIPTIONS/NOTIFICATIONS Fig 6. SIP SUBSCRIBE and Fuego PUBLISH

14. Fuego System SIP DomainGateway SUBSCRIBE Forward SUBSCRIBE NOTIFY Forward NOTIFY OK Process subscription Mapping, reformat NOTIFY OK SIP AND FUEGO SUBSCRIPTIONS/NOTIFICATIONS Fig 7. FUEGO SUBSCRIBE and SIP NOTIFY Mapping, reformat SUBSCRIBE

15. MOBILITY IN THE INTERWORKING ARCHITECTURE Interdomain mobility: Need buffering of messages at the gateway Roaming clients can send a signal to the gateway informing their location update, and get the buffered messages Intradomain mobility: Intradomain terminal mobility is possible in both the SIP and Fuego domains Disconnected operation should be supported for user mobility

16. ADVANTAGES OF THE GATEWAY COMPONENT Performed scalability and performance test for the gateway Used the presence event package Advantages: + Supports extensibe implementation Experimentatal observation: + Transparent architecture + No modifications in the API of the interworked domains

17. Conclusion Future Work: Enhancing gateway functionality by providing filtering support, and load balancing Under heterogenous environments interworking of different event standards is essential Investigate the possibilities to provide various mobility support such as session mobility

18. REFERENCES National Institute of Standards and Technology (NIST) – SIP (Session Initiation Protocol) Stack and Proxy: http://snad.ncsl.nist.gov/proj/iptel/ Java APIs for Integrated Network (JAIN) – Session Initiation Protocol (SIP) API: http://www.jcp.org/aboutJava/communityprocess/final/jsr032/

19. QUESTIONS ?

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