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Web Services Composite Application Framework - OASIS

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					Web Services Composite Application
                       Framework

                   Eric Newcomer, WS-CAF Co-Chair
                                     April 26, 2004
What is WS-CAF?
• Collection of 3 specifications:
   – WS-Context – generic context management
   – WS-Coordination Framework - for pluggable coordination
     protocols
   – WS Transaction Management - three transaction models for
     Web services:
       • ACID Transaction – focus on interoperability
       • Long Running Action – compensation based
       • Business Process - Coordination of arbitrary runtimes and
         transaction models
   – Extensible
       • Updated with new models as and when required
• WS-Ctx and WS-CF can be used independently
WS-CAF (cont)
• Intended to complement MSFT/IBM/BEA work
• Submitted to OASIS by Arjuna, Fujitsu, IONA,
  Oracle, and Sun in October
• Now progressing in WS-CAF TC
  – 62 members
  – Spec update/interop demo roadmap for 2004
     • WS-Context – April
     • WS-Coordination Framework – August
     • WS-Transaction Management – December
WS-Context specification
• Context and “life-cycle” service
   – Basic aspect of WS architecture
• Defines notion of an activity
   – Unit of work
   – Shared scope of persistent data
   – Basic context associated with activity
• Context Service maintains context for each
  activity
   – May be co-located or separate service
WS-Context Goals
• To provide a basic context service for Web
  services
  – Lots of different specifications need one:
     •   WS-Security
     •   WS-BPEL
     •   WS-Resource Framework
     •   WS-Distributed Management
• Provide ability to do correlation at a minimum
  – No augmentation of framework required to use it
• Basic context management to complex systems
Business process model
• Aimed at long running interactions that span
  different domains and models
  – Workflow
  – Messaging
  – Database, ERP, etc.
• Federated systems that can’t/won’t expose
  back-end implementations
• Assign coordinators per domain
• Adds a coordinator-coordinator protocol
Business process approach
• All operations reside within business domains
  – Recursive structure is allowed
  – Each may represent a different transaction model
• Business process is split into business tasks
  – Execute within domains
  – Compensatable units of work
     • Forward compensation during activity is allowed
        – Keep business process making forward progress

• Coordinator can invoke synchpoint to discover
  current state of transaction
Business Process Model
• Supports synchronous and asynchronous interactions
   – Users can submit work and call back later
   – Or interact synchronously (traditionally)
• Optimistic rather than pessimistic
   – Assumes failures are rare and can be handled offline if
     necessary
• Each domain is exposed as a subordinate coordinator
   – Responsible for mapping incoming BP requests to domain
     specific protocol
• Protocol messages
   – checkpoint, confirm, cancel, restart, workStatus
WS-Coordination Framework
• The Coordinator Service
  – Provides a participant registration endpoint
  – Coordination status and identity
  – Can be driven at arbitrary points during activity
• Subordinate coordinator
  – Participant as far as coordinator is concerned
  – Coordinator as far as participant is concerned
• Can be used to resolve protocol differences
  – Provide basic interoperability
  – Bridge disparate transaction models
Business
process                 Database schemas
                               and
architecture            stored procedures




                          Web
       .Net Server
                        services
            or
          App
         Server                                     Adapters to
          with                 Flow                 ERP, CRM,
          Web                                     Accounting, etc.
         service
          APIs




                      Message queuing system
                     A2A/B2B Integration broker

				
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