Bpel for Beginners

7/28/2019 Bpel for Beginners

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Business Process Execution

Language (BPEL)


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What is BPEL?

BPEL stands for Business Process ExecutionLanguage, and comes from a standardsconsortium consisting of BEA Systems, IBM, and

Microsoft. BPEL is an XML-based language for enabling task

sharing across multiple enterprises using acombination of Web services.

BPEL is based on the XML schema, simple objectaccess protocol (SOAP), and Web servicesdescription language (WSDL).


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What is BPEL?

BPEL directly addresses these business processchallenges:

Coordinating asynchronous communicationbetween services

Correlating message exchanges between parties

Implementing parallel processing of activities

Manipulating data between partner interactions

Supporting long running business transactionsand activities, and providing consistent exceptionhandling.


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What is BPEL?

The BPEL language enables you to define how to:

Send XML messages to, and asynchronously

receive XML messages from, remote services

Manipulate XML data structures

Manage events and exceptions

Design parallel flows of process execution

Undo portions of processes when exceptions

occur


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The Role of BPEL

The BPEL specification defines the syntax andsemantics of the BPEL language, whichcontains a variety of process flow constructs.

It allows for Conditional branching,

Parallel process flows

Nested sub-processes Process joins


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Oracle BPEL Process Manager

Web service standards such as XML, SOAP, and WSDL

Dehydration (enables the states of long-runningprocesses to be automatically maintained in adatabase) and correlation of asynchronous messages

Service-oriented architecture (SOA) Parallel processing of tasks

Fault handling and exception management during bothdesign time and run time

Event timeouts and notifications Compensation mechanisms for the implementation of

long-running transactions


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Oracle BPEL Process Manager

Scalability and reliability of processes

Management and administration of processes

Version control

Audit trails for tracing business flow history

Installation on multiple operating systems and integration withmultiple application servers (for example, Oracle Application Server,BEA WebLogic, and JBoss) and databases.

Oracle BPEL Process Manager adds value and ease of use to BPELfunctionality by providing support for the following in JDeveloperBPEL Designer:

Transformations, workflows, worklists, notifications, and sensors Technology adapters (file, FTP, database, advanced queuing (AQ),

Java Messaging Service (JMS), and Oracle Applications for Oracle E-Business Suite)


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JDeveloper BPEL Designer

JDeveloper BPEL Designer is integrated with

Oracle JDeveloper. Oracle JDeveloper is an

integrated development environment (IDE) for

building applications and Web services using

Java, XML, and SQL standards.


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Composite


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Partner Links

Partner Link describes the shape of the relationship with apartner by describing the Port Types used in a peer topeer relationship

Example:


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Partner Links

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 serviceprovided by the process

invoke

Outbound request servicerequired by the process


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Partner Links


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Variable Element

Variable construct is used to state informationrelated to workflow logic

Variables can contain entire messages and data

sets formatted as XSD schema types Example:


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Variables

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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Basic Activities

receive reply

invokeInvoke a one-way orrequest-response operation

Do a blocking wait for amatching message to arrive/ send a message in reply

validate

assignUpdate the values ofvariables or partner linkswith new data

Validate XML data storedin variables

throw

rethrow

Generate a fault from insidethe business process

Forward a fault frominside a fault handler

exitImmediately terminateexecution of a business

process instance

compensate

compensateScope

Invoke compensation onall completed child scopes

in default order

Invoke compensation onone completed child scope

waitWait for a given time

period or until a certaintime has passed

empty No-op instruction fora business process


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process

flowContained activities areexecuted in parallel,partially ordered throughcontrol links

sequenceContained activities areperformed sequentially inlexical order

whileContained activity isrepeated while a predicateholds

Contained activity isrepeated until a predicateholds

pick Block and wait for asuitable message to arrive

(or time out)

forN Contained activity isperformed sequentially orin parallel, controlled by aspecified counter variable

if-elseif-else Select exactly one branchof activity from a set of

choices

scope Associate contained activitywith its own local variables,

partner links, etc.,and handlers

Structured Activities

2. N.1.

B C

A

cc1 c2

2. N.1.

AM2M1


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Scopes

Scopes provide a context which influencesthe execution behavior of its enclosedactivities

Local declarations partner links,message exchanges, variables, correlationsets

Local handlers

event handlers, faulthandlers, a termination handler, and acompensation handler


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PROCESS FLOW


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BPEL Syntax ExampleProcess Steps


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BPEL Syntax ExampleProcess Steps

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