bpel session

8/8/2019 BPEL Session

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Business Process Business Processes Automation & Web

Service Standards

WS-BPEL Overview BPEL4People & WS-HumanTask


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A business process is a collection of interrelated tasks,which are designed to deliver a particular result

Types of business processes Management processes - processes that govern the operation of

a system Operational processes - processes that constitute the core

activities of the business and delivers the primary value of theorganization

Supporting processes - which support the core processes A business process can be decomposed into several sub-

processes, which have their own attributes, but arealigned with the goal of the overall process

The analysis of business processes typically includes themapping of processes and sub-processes down to anactivity level

Business processes can be automated through BPMsoftware and workflow


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Key Questions for Workflow Design Who Should?

Who is involved in the process

Do What?

What tasks/activities need to be performedTo What?

What entities (objects) and data involved

When? What starts and stops the process

In What Order? What is the sequence and interrelationship between tasks

Why? What is the value proposition of using workflow


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Improve the speed of a business process Improve the consistency of a business process

Improve the quality of a business process


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Business Process

Business Processes Automation & WebService Standards



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Messaging

Qualityof Service

Transport

Description

Components

Transport

Interface + Bindings

Composite

XML Non-XML

Security

Policy

Discovery,Negotiation,Agreement

Atomic

Orchestration Protocols State

ReliableMessaging

Transactions

ComponentModel


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Messaging

Qualityof Service

Transport

Description

Components

Transport


Composite

XML Non-XML

Security

Policy


Atomic


ReliableMessaging

Transactions

ComponentModel

WS-RM

WSDL* WS-Policy*

HTTP, TCP/IP, SMTP, FTP,

UDDI,WS-Addr,Metadat

aExch.,

WS-CWS-N* WS-RFWS-BPEL

WS-Security*WS-ATWS-BA

SOAP, WS-Addr* JMS, RMI/IIOP, ...

SCA


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Messaging

Qualityof Service

Transport

Description

Components

Transport


Composite

XML Non-XML

Security

Policy


Atomic


ReliableMessaging

Transactions

ComponentModel

WS-RM

WSDL* WS-Policy*

HTTP, TCP/IP, SMTP, FTP,

UDDI,WS-Addr,Metadat

aExch.,

WS-CWS-N* WS-RFWS-BPEL

WS-Security*WS-ATWS-BA

SOAP, WS-Addr* JMS, RMI/IIOP, ...

SCA


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Business Process

Business Processes Automation & WebService Standards



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Web Services Business Process ExecutionLanguage (WS-BPEL) is a language for describingbusiness processes based on Web Services Processes described using WS-BPEL execute functionality

by using Web Service interfaces exclusively WS-BPEL Specification is administered by OASIS

WS-BPEL is an orchestration language. Orchestration specifies an executable process that

involves message exchanges with other systems, such

that that the message exchange sequences are controlledby the orchestration designer.


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WS-BPEL process definition Recursive composition and partner links Variables

Correlation sets Basic and structured activities Scopes Compensation handling


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process

imports

Declare dependencieson external XMLSchema or WSDLdefinitions

extensions

Declare namespaces ofWS-BPEL extension

attributes and elements

variables

Data holding state of abusiness process orexchanged withpartners

partnerlinks

Relationships that aWS-BPEL process will

employ in its behavior

correlationsets

Application data fieldsthat together identify

a conversation

messageexchanges

Relationship betweeninbound and outbound

message activities

eventhandlers

Concurrently processinbound messages ortimer alarms

faulthandlers

Deal with exceptionalsituations in a process

primaryactivity

Perform the processlogic any number ofactivities may berecursively nested

XMLschemas

WSDLdefinitions


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WebService

Financial

institutionsWeb serviceimplementation(Loan Approver)

WebService

WSDLLoanApprovalPortType

Loan Approval Process

invoke

receive

reply

WS-BPEL processes are

exposed as Webservices

to business partners

WS-BPEL processesinteract

with Web servicesexposed

by business partners


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WDSL describes functionality of services provided bya partner

Partner Link describes the shape of the relationshipwith a partner by describing the Port Types used in apeer to peer relationship

Example:

Reference to WDSLportType element


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process

partnerlink

partner link type

Peer-to-peer conversational partner relationship

WSDLport type

myRole

Provided port type

WSDLport type

partnerRole

Required port type

receive

Inbound request service provided by theprocess

invoke

Outbound request service required by the

process


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Variable construct is used to state informationrelated to workflow logic

Variables can contain entire messages anddata sets formatted as XSD schema types

Example:

Message Namefrom Partner

Process Definition


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process

assign

xsl:transform

receive

request

response

invoke

request

reply

response

42

WSDLmessage

WSDLmessage

WSDLmessages

Variables defined using WSDL messages

42XMLschemas

XML Schemaelements / types

Variables defined using XML schema elements or types


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How to identify stateful instances via stateless WS interfaces? A process instance is assigned one or more keys

Business data is used as key, e.g., customerID

A key can be compound, e.g., (customerID, orderNumber)

WS-BPEL calls a key a correlation set it is used to correlate anincoming message with a process instance

Process 4(0123,15)

Process 3(0815,42)

Process 2(4711,37)

Process 1(0815,12)

0815 42

Message 2

customerID

orderNumber

4711 37

Message 1


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process

receive reply

invokeInvoke a one-way or

request-responseoperation

Do a blocking wait for amatching message toarrive / send a messagein reply

validate

assignUpdate the values ofvariables or partnerlinks with new data

Validate XML datastored in variables

throw

rethrow

Generate a fault frominside the businessprocess

Forward a fault frominside a fault handler

exit

Immediately terminateexecution of a business

process instance

compensate

compensateScope

Invoke compensationon all completed child

scopes in default order

Invoke compensationon one completed child

scope

waitWait for a given time

period or until a certaintime has passed

empty No-op instruction fora business process

extensionActivityWrapper for language

extensions


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process

flowContained activities areexecuted in parallel,partially orderedthrough control links

sequenceContained activities areperformed sequentiallyin lexical order

whileContained activity isrepeated while apredicate holds

repeatUntilContained activity isrepeated until apredicate holds

pick Block and wait for asuitable message toarrive (or time out)

forEach Contained activity isperformed sequentiallyor in parallel, controlled

by a specified countervariable

if-elseif-else Select exactly onebranch of activity from

a set of choices

scope Associate containedactivity with its own local

variables, partner links,etc.,

and handlers

2. N.1.

B C

A

c

c

c1 c2

2. N.1.

AM2M1


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process

scope

scope

scope

scopescope

scope

scope

Scopes provide acontext whichinfluences theexecution behavior ofits enclosed activities

Isolated scopes providecontrol of concurrentaccess to sharedresources

scope

Local declarations partner links, message

exchanges, variables,correlation setsLocal handlers eventhandlers, faulthandlers, a terminationhandler, and acompensation handler

Compensation handler toundo persisted effects of

already completedactivities

Termination handler todeal with forced scope

termination (externalfaults)

primary activity

scope


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process

scope

invoke

invoke

invoke

faulthandlercompensate

compensation

handlercompensatecompensation

handlercompensation

handlerinvoke

invoke

1. Do some work (successfully invoke two services)

2. Invoke anotherservice(throws fault)

3. The faulttriggersthe process-levelfault handler

4.Compensatepreviouswork5. Propagate

compensation

6. Undo work(in reverseorder)


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Business Process Business Processes Automation & Web

Service Standards



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BPEL4People Definition of human interactions within WS-BPEL

processes Specification built on top of WS-BPEL 2.0

WS-HumanTask Definition of service-enabled human tasks and

notifications Coordination protocol used to control autonomy

and life cycle of service-enabled human tasks inan interoperable manner

Interoperable programming interface enablingtask client applications to work with humantasks

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