Chapter 13 process specifications
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Chapter 13: Process Specifications. Service-Oriented Computing: Semantics, Processes, Agents – Munindar P. Singh and Michael N. Huhns, Wiley, 2005. Highlights of this Chapter. Processes Describing Dynamics with UML Workflows Business Process Languages BPEL4WS (WS-BPEL) ebXML RosettaNet

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Chapter 13: Process Specifications

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Chapter 13 process specifications

Chapter 13:Process Specifications

Service-Oriented Computing: Semantics, Processes, Agents– Munindar P. Singh and Michael N. Huhns, Wiley, 2005


Highlights of this chapter

Highlights of this Chapter

  • Processes

  • Describing Dynamics with UML

  • Workflows

  • Business Process Languages

    • BPEL4WS (WS-BPEL)

    • ebXML

    • RosettaNet

  • PSL: Process Specification Language

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Processes and workflows

Processes and Workflows

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


A process is abstractions

A Process Is … [Abstractions]

Orchestration: A partial order of actions (activity graph, script) under the control of a central conductor; akin to a workflow [Global view; central]

Workflow: narrower concept than process; emphasizes control and data flows from a central perspective; usually tool-specific and focused on human tasks

Choreography: An exchange of messages among participants; akin to a conversation as described by WSCL, WS-CDL, ebBP [Global view; distributed]

Collaboration: A joint set of activities among business partners [Local views; distributed]

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Telecommunications order processing

Telecommunications Order Processing

Older workflow tools support specialized (ad hoc) notations

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Describing dynamics with uml

Describing Dynamics with UML

UML Activity Diagrams are practically identical to BPMN (Business Process Modeling Notation) and WS-BPEL (Business Process Execution Language)

  • Sequence: a transition from one activity to the next

  • Branch: a decision point among alternative flows of control

  • Merge: where two or more alternative flows of control rejoin

  • Fork: a splitting of a flow of control into two or more concurrent and independent flows of control

  • Join: a synchronization of two or more concurrently executing flows of control into one flow

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Uml activity diagram

UML Activity Diagram

Implementation of a vendor’s purchase process

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Flow interoperability patterns

Flow Interoperability Patterns

  • Among others:

  • Chained

  • Nested

  • Synchronized

  • What guarantees would you obtain from each pattern?

  • How would you accommodate exceptions in each pattern?

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Ws bpel metamodel

WS-BPEL Metamodel

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Process as a composite web service

Process as a Composite Web Service

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Stock quote service in ws bpel

Stock Quote Service in WS-BPEL

<process name="simple" targetNamespace="urn:stockQuoter" xmlns:tns="urn:stockQuoter" xmlns:sqp="http://tempuri.org/services/stockquote" xmlns=&BPEL;/>

<containers>

<container name="request" messageType="tns:request"/>

<container name="response" messageType="tns:response"/>

<container name="invocationRequest" messageType="sqp:GetQInput"/>

<container name="invocationResponse" messageType="sqp:GetQOutput"/>

</containers>

<partners>

<partner name="caller" serviceLinkType="tns:StockQuoteSLT"/>

<partner name="provider" serviceLinkType="tns:StockQuoteSLT"/>

</partners>

<sequence name="sequence">

<receive name="receive" partner="caller" portType="tns:StockQuotePT"

operation="wantQuote" container="request" createInstance="yes"/>

<assign> <copy>

<from container="request" part="symbol"/>

<to container="invocationRequest" part="symbol"/>

</copy> </assign>

<invoke name="invoke" partner="provider" portType="sqp:StockQuotePT"

operation="getQuote" inputContainer="invocationRequest" outputContainer="invocationResponse"/>

<assign> <copy>

<from container="invocationResponse" part="quote"/>

<to container="response" part="quote"/>

</copy> </assign>

<reply name="reply" partner="caller" portType="tns:StockQuotePT" operation="wantQuote" container="response"/>

</sequence>

</process>

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Electronic business extensible markup language ebxml

Electronic Business Extensible Markup Language (ebXML)

  • Established jointly by

    • UN-CEFACT (United Nations Centre for Trade Facilitation and Electronic Business)

    • OASIS (Organization for the Advancement of Structured Information Standards)

  • Provides specification languages for business processes, business messages to facilitate trading agreements

  • Motivations:

    • Global standard for companies of all sizes

    • Automate finding business partners

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Ebxml vocabulary

ebXML Vocabulary

  • Unified Modeling Methodology (UMM)

    • Specialized UML for Business Processes

  • Collaboration Protocol Profile (CPP)

    • Describes a business with respect to its roles in specified processes, the messages it exchanges, and the transport mechanism (e.g., HTTPS)

  • Collaborative Partner Agreement (CPA)

    • Intuitively, like an “intersection” of two CPPs

    • Technical agreement between two or more partners

    • May be legally binding

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Design of an ebxml system

Design of an ebXML System

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Discover partner information and negotiate

Discover Partner Information and Negotiate

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Implementing ebxml

Implementing ebXML

  • ebXML is a set of specifications: of collaborations and repositories for discovering business partners

    • Build and deploy its custom ebXML-compliant application to implement necessary roles in different collaborations

    • Use COTS ebXML compliant applications and components (from ERP vendors)

  • Business Service Interface (BSI): a wrapper that enables a given party to participate properly in an ebXML exchange

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Business service interface

Business Service Interface

  • Interfaces with the legacy system to have it play a role in a specific protocol (e.g., vendor in 3A4)

  • Is aware of its own Collaborative Protocol Profile

  • Handles transactions based on all current agreements (CPAs)

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Rosettanet pip for creating a purchase order the content for ebxml

RosettaNet PIP for Creating a Purchase Order: The Content for ebXML

  • PIP: Partner Interface Process; an interaction protocol

  • ebXML BPSS: language for specifying PIPs

  • Two-party protocols

  • Request-response only

  • No specification of the meanings of the messages exchanged

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Exercise exception in a process

Exercise: Exception in a Process

Recording student registration

  • Assume that each database management system supports two-phase commit for transactions

  • Task #2 checks that the student has completed the necessary prerequisites for all the courses for which the student is registering

    Consider a scenario where Tasks #3, #4, #5 succeed, but Task #2 fails

  • As the system administrator, what operations would you have to perform in order to restore consistency to your system?

  • How would you modify the process to prevent problems such as this from occurring?

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


Chapter 13 summary

Chapter 13 Summary

  • In virtually all serious applications of SOC, services are composed into processes

  • Current approaches for process modeling are based on workflow abstractions

    • WS-BPEL enables specification of processes

    • ebXML also considers the life cycle of processes

    • RosettaNet is an application of ebXML

  • Flows interact in various ways

    • Exceptions in flows can be handled via (extended) transactions or through application-specific means (where interesting patterns can arise)

Service-Oriented Computing: Semantics, Processes, Agents - Munindar Singh and Michael Huhns


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