WS-BusinessActivity using WS-Coordination

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WS-BusinessActivity using WS-Coordination

• A bare-bone implementation

Presented by Krishnan Narayanan Guided by Dr.
Bina Ramamurthy Course CSE 622, Spring 2006
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Outline

• Motivation Approach
• Overview of protocols
• System Design
• Applications
• Demo along the way!

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Motivation

• Build a working model of WS-BA protocol on top
  of which applications can be built more of an
  academic test bed
• Gain practical experience in implementing
  protocols
• Understand the intricacies involved in
  translating standards into working model may be
  this will help us appreciate the part played by
  vendor dependant design?

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What is What is NOT?

• Design compliant with the standards
  specification
• Not STRICT adherence to the semantics of WS
  suite of protocols (WS-Policy, WS-Addressing,
  WS-Security)
• Not implemented as a web service guess why?
• Not a complete implementation basic framework
  is ready. Future extensions needed/possible.
• Only one protocol Automic Outcome/BAWithPartici
  pantCompletion

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Some Technical Details

• Messages - SOAP with Attachments API for Java
• Messaging SOAP/XML
• Transport Protocol HTTP
• Supporting Framework Servlet
• Container Support Apache Tomcat
• Callbacks Notifications Thread Model

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WS-Coordination a brief overview
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WS-BA Overview

• Enables multiple business activities to work in
  a coordinated fashion
• Uses WS-Coordination as the underlying framework
• 2 different coordination types
• Atomic Outcome All participants are driven to
  same end state
• Mixed Outcome Each participant is attended
  individually
• 2 different coordination protocols
• Participant Completion Participant drives the
  decision making
• Coordinator Completion Coordinator drives the
  decision making

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Applying WS-Coordination to WS-BA with
Participant Completion
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Coordinator - Activation Component

• Purpose
• Manages a list of activities
• Design
• Implemented as a Singleton class
• Details
• Maintains a static list of on-going Activities
• Generate and assigns unique id for the activity
  (callbackRef)
• CoordinationContextResponse createCoordinationCont
  ext(CoordinationContextRequest)

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Coordinator - Registration Component

• Registers participant into an active Activity
• Performs validation by interacting with
  Activation manager
• Generate a Unique ID for the Participant add it
  to the Activity list (participantRef)
• No security measures in place WS-Security
• Handles the participant to the Protocol Manager
• RegisterResponse register(Register regRequest)

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Coordinator Protocol Handler

• Implements the state machine specified by the
  standard
• Reflects Coordinators view of Participant state
• Events specified by the standard are translated
  into SOAP messages
• State transitions are triggered by generating
  appropriate event
• One instance for each Participant

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Participant Protocol Handler

• Implements the Participants view of the state
  machine
• Same as Protocol Handler employed by Coordinator
  Events States

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Callbacks

• Why is it needed?
• Events can be generated either by coordinator
  participants.
• How is it implemented?
• Queue for managing the list of to process
  events.
• Callback manager monitors the event queue and
  triggers callback.

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Pieces put together
Protocol Handler Design
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WS-BA - Protocol Handler at work
An Illustration
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Is the WS-BA PC Protocol State Machine Deadlock
Proof?

• Is there a possibility for the protocol to get
  deadlocked?
• If so, can the nature of the Business Process
  play a role to avoid such a situation?
• If yes, is it good or bad?
• State Machine

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Extensions Applications

• WS-Notification can be utilized to implement the
  callbacks for the Coordinator.
• Can be integrated with BPEL to create
  coordinated composition of web services.

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References Questions

• WS-Coordination ftp//www6.software.ibm.com/softw
  are/developer/library/WS-Coordination.pdf
• WS-BA
• ftp//www6.software.ibm.com/software/developer/li
  brary/WS-BusinessActivity.pdf
• Web services composition, integration and
  interoperability Composition of coordinated web
  services