Download view slides

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
architecture
.Net Server
or
App
Server
with
Web
service
APIs
Database schemas
and
stored procedures
Web
services
Flow
Message queuing system
A2A/B2B Integration broker
Adapters to
ERP, CRM,
Accounting, etc.