Multimedia services over networks

1. Multimedia services over networks Framework/ Architecture Review/background Service provider Multimedia Services Delivery Bind Publish Deployment/ Management Multimedia system Service registry Service client Discovery Transactions/mobility/locations

2. Multimedia services • Deployment • Chih-Cheng Lo, Wen-Shyen E. Chen: Deploy Multimedia-on-Demand Services over ADSL Networks • Multimedia service composition • Klara Nahrstedt, Wolf-Tilo Balke: A taxonomy for multimedia service composition • Transaction • Stefan Tai, Thomas A. Mikalsen, Eric Wohlstadter, Nirmit Desai, Isabelle Rouvellou: Transaction policies for service-oriented computing.

3. Deploy Multimedia-on-Demand Services Introduction Services Deployment and Broadband Services System Architecture Signaling Control Conclusion

4. Deploy Multimedia-on-Demand Services • A large-scale Multimedia-on-Demand (MOD) system • Provide both multicast and unicast streaming services • ADSL networks • Services of MOD system • True VoD, Near VoD, etc. • Elements • Set-top Unit • Video servers • Storage system

5. Architecture of HFC networks

6. ADSL-based network architecture

7. System architecture • Distributed servers architecture • Components and functions

8. System architecture • STB/STB Server • Access Network • Video Servers • Media storage and controllers • Video Server Gateway • Portal of multimedia services • State of STB • Menu • Coordinate with local system management system (LSMS) • Reserve or release resources

9. System architecture • Internet access Management System • Video Server System • Multicast, unicast • Media storage component • Media management component • Service Management System • Local service management system (LSMS) • Bandwidth management, control video output • Global service management system (GSMS) • Ordering system • Billing system

10. Signaling control

11. MoD Systems • MoD systems must realize MoD services • LSMS – service registry • Client service interactions • Video server gateway Service provider Publish Bind Multimedia Services Service registry Service client Find/discovery

12. A Taxonomy for MS Composition • A taxonomy for the composition of services • Methodology for multimedia service compositions • Built on top of existing components and re-use individual services • Scalable, easy-programming and flexible manner • Bridges between the web service and multimedia service communities • Integration metrics • Time • Refine metrics

13. A Taxonomy for MS Composition • Goals • Multimedia service composition by taking into account the web service composition model • Demonstration • Apply the taxonomy to different service composition instances • Email services • Instant messaging • Internet telephony • Video and audio conferencing

14. Composite service model • Web service model Service provider WSDL Bind Publish UDDI SOAP Service registry Service client Find/discovery Simple workflow-based process: simple to composite services

15. Web services

16. Extened SOA

17. Composite multimedia service model • Service components connected by a directed acyclic • service dependency graph • S1: encoding • S2: transcoding • S3: transmission services

18. Composite multimedia service model

19. Methodology and metrics • Two levels • Time • Other metrics • Number of services • Performance quality • Service parameters • Content type • Infrastructural support • Instantiation and delivery

20. Metrics • Time • Number of services • Performance quality • Multimedia • Content type • Semantic type • Infrastructural support Multimedia services Web services

21. Service composition instances – time metric Email: coarse time scale IM: tight time scale

22. Service composition instances – time metric Functionally and time-dependent Functionally independent and time-dependent Begin-cascaded services End-cascaded services

23. Service composition instances – time metric

24. Successive service compositions • Number of services • Performance quality • Content type • Infrastructural support

25. Concurrent service compositions • Number of services • Performance quality • Content type • Infrastructural support

26. Summary • Complex multimedia service are instantiated by composing relatively simple services • Metrics • Organized multimedia composition soaces • Multimedia specific ontologies • Content type • Issues • Semantics of multimedia services • Discovering semantically • Quality-aware

27. Transactions • Definition (Database) operations can be gathered together to form a unit of execution program that is called a transaction. Begin_transaction (initial_service_state) One or more service operations if (reach new_service_state) then Commit_transaction (new_service_state) else Abort_transaction (initial_service_state)

28. The ACID properties of transactions • Atomicity. Either all database operations of a transaction program are completely executed, or none of the database operation of this transaction program is executed. • Consistency. A transaction transforms the database from one consistent state to another. • Isolation. An on-going transaction must not interfere with other concurrent transactions, or be able to view intermediate results of other concurrent transactions. • Durability. The result of a transaction that has successfully committed is permanent in the database.

29. Transaction policies for service-oriented computing • Requirement or preference of services • Reliable messenging servive • Exactly-one delivery • Services extra-functional capabilities, requirements and preferences must be declared and matched • Transaction • Transaction policies • Assertions for transactional coordination that individual service providers and service client declare • Transaction coupling modes • The contract that matches service provider and clients transaction policies

30. Three transaction styles • Direct transaction processing (DTP) • Invocation of servers is synchronous • Queue transaction processing (QTP) • Asynchronous invocation • Compensation-based transaction processing (CTP) • Forward and backward recovery • Can be a DTP or QTP • Using middleware • Policy matching • Transactional business process execution

31. Three transaction styles -cont

32. Three transaction styles -cont

33. Transaction policies • Direct transaction processing (DTP) • Tight coupling between client and server • Strong isolation • Queue transaction processing (QTP) • Loose coupling, asynchronous transactions • Compensation-based transaction processing (CTP) • Support atomicity and consistency of long-running business processes • Allow transactions to commit during the process • Clients vs. Servers transaction policies • Capabilities, requirements, preferences

34. Transaction policies -cont • Abstract vs. Concrete policies • Abstract: describe and match transaction capabilities and requirements • Concrete: specific formats and protocols used to implement transactions

35. Transaction policies -cont • Transaction policies are defined in the WS-Policy language • <wsp:_>

36. Transaction coupling modes • Verification, and matching the Business Process Execution Language for WS (BPEL) of client and server policies Middleware prototype