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A Gateway F or SIP Event Interworking. - Sasu Tarkoma & Thalainayar Balasubramanian Ramya. MOTIVATION. Interworking of SIP event framework with the generic publish/subscribe system. Challenges:. SIP Event Framework does not support anonymous
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A Gateway For SIP Event Interworking -SasuTarkoma & Thalainayar Balasubramanian Ramya
MOTIVATION • Interworking of SIP event framework with the generic publish/subscribe system Challenges: • SIP Event Framework does not support anonymous one-to-many event dissemination • 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
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 3rd Generation Partnership Project (3GPP), as the session establishment protocol for the 3GPP IP Multimedia Core Network Subsystem (IMS)
BACKGROUND INFORMATION SIP Application Areas: • Internet Telephony • Control Applications • E-Commerce • Multimedia Conferences • Instant Messaging
SUBSCRIBE 200 NOTIFY 200 NOTIFY 200 SIP EVENT FRAMEWORK SIP Event Framework: An extension of Session Initiation Protocol, described in RFC 3265 Methods supported: SUBSCRIBE, NOTIFY SUBSCRIBER NOTIFIER Fig 1. SIP Event Subscription and Notification
Forward notification to subscriber proxy Forward subscription to notifier proxy DNS lookup Proxy query Update location server DNS Forward notification to subscriber Forward SUBSCRIBE to notifier Notification response to proxy SIP Proxy1 (Redirect mode) Registrar SIP Proxy2 (Redirect mode) Location Server Forward SUBSCRIBE Forward notification to notifier proxy Forward request to notifier register register UAC3 UAC1 UAC2 SIP DOMAIN Fig 2. Working of SIP Domain
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 Registrar: Maintains registered clients information, queries and gets recent updates from Location Server Redirect Server (Redirect Mode): Provides the contacted client’s current address to the contacting client Location Server: Stores updated client information
APPLICATION AREAS OF CONTENT BASED PUB/SUB EVENT MODEL • Active Badge Systems • Proximity Sensors • Information and Multimedia Delivery Services • Positioning Systems
Subscribe P1 S1 Subscribe() Publish P2 S2 Publish() Publish Sn Pn Unsubscribe Unsubscribe() WORKING OF PUBLISH/SUBSCRIBE EVENT MODEL Publishers Consumers Event Service Fig 3. Publish/Subscribe Event model
Gateway SIP Domain Pub/Sub Domain I I O O GATEWAY DESIGN Conversion,Mapping, State Fig 4. Gateway Design
SIP clients G A T E W A Y Fuego Clients JAIN-SIP Proxy Fuego Event Service NIST-SIP STACK IMPLEMENTATION ARCHITECTURE subscribe/ notify subscribe/ publish Fig 5. Implementation Architecture
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
GATEWAY FUEGO SYSTEM SIP DOMAIN SUBSCRIBE Mapping, reformat SUBSCRIBE Forward SUBSCRIBE Process subscription Subscription status Create SIP response Forward SIP response PUBLISH Mapping, reformat PUBLISH Forward NOTIFY OK SIP AND FUEGO SUBSCRIPTIONS/NOTIFICATIONS Fig 6. SIP SUBSCRIBE and Fuego PUBLISH
Fuego System SIP Domain Gateway SUBSCRIBE Mapping, reformat SUBSCRIBE Forward SUBSCRIBE Process subscription OK NOTIFY Mapping, reformat NOTIFY Forward NOTIFY OK SIP AND FUEGO SUBSCRIPTIONS/NOTIFICATIONS Fig 7. FUEGO SUBSCRIBE and SIP NOTIFY
MOBILITY IN THE INTERWORKING ARCHITECTURE Intradomain mobility: • Intradomain terminal mobility is possible in both the SIP and Fuego domains • Disconnected operation should be supported for user mobility 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
ADVANTAGES OF THE GATEWAY COMPONENT Advantages: + No modifications in the API of the interworked domains + Supports extensibe implementation + Transparent architecture Experimentatal observation: • Performed scalability and performance test for the gateway • Used the presence event package
Conclusion • Under heterogenous environments interworking of different event standards is essential Future Work: • Enhancing gateway functionality by providing filtering support, and load balancing • Investigate the possibilities to provide various mobility support such as session mobility
REFERENCES • Java APIs for Integrated Network (JAIN) – Session Initiation Protocol (SIP) API: http://www.jcp.org/aboutJava/communityprocess/final/jsr032/ • National Institute of Standards and Technology (NIST) – SIP (Session Initiation Protocol) Stack and Proxy: http://snad.ncsl.nist.gov/proj/iptel/