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Kasun Indrasiri Associate Technical Lead PMC, Apache Synapse Member, Integration MC WSO2 Inc.

Introduction to WS-BPEL and WSO2 BPS. Kasun Indrasiri Associate Technical Lead PMC, Apache Synapse Member, Integration MC WSO2 Inc. May 2013. Agenda. What is a Business Process / WS-BPEL WSO2 Business Process Server Introduction to BPEL

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Kasun Indrasiri Associate Technical Lead PMC, Apache Synapse Member, Integration MC WSO2 Inc.

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  1. Introduction to WS-BPEL and WSO2 BPS Kasun Indrasiri Associate Technical Lead • PMC, Apache Synapse Member, Integration MC WSO2 Inc. May 2013

  2. Agenda • What is a Business Process / WS-BPEL • WSO2 Business Process Server • Introduction to BPEL • Developing Business Processes with WSO2 Developer Studio

  3. Business Process • Business process is a set of logically related activities • These activities are performed in a predefined order to achieve a business goal

  4. Example process

  5. Orchestration vs. Choreography • Orchestration • Business process with central coordinator • WS-BPEL • Choreography • Business collaboration

  6. WS-BPEL • Business Process Execution Language • An Oasis standard • XML based language for service composition • BPEL defines xml based grammar for describing the logic to coordinate and control interactions between Web Services • Create, Consume and Aggregate services

  7. Why use WS-BPEL • Increase efficiency of business • No need to worry about the coordination of the process • Portable business processes • Built on top of standard compliant web services infrastructure • Industry wide language for implementing business processes • Common skill set • Native support for long running processes • Execute asynchronous processes that takes days to complete • Managed execution

  8. WSO2 Business Process Server • Executes business processes written using WS-BPEL standard • Powered by Apache ODE ( ode.apache.org ) • WS-Human Tasks and BPEL4People • Provides a Management Console to • View and Manage Processes / Human Tasks • View and Manage Instances / Tasks • Configure QOS …

  9. Introduction to WS-BPEL

  10. Want to implement a BPEL Process ? • You should have some knowledge on • XML • XML Namespaces • XML Schema • WSDL • XPath • XSLT

  11. Structure of a WSDL • <types> • <message/>+ • <portType><operation>+</portType> • <binding/>+ • <service><port/></service>

  12. BPEL Document Structure <process> <partnerLinks><partnerLinks> <variables></variables> <messageExchanges></messageExchanges> <correlationSets></correlationSets> <faultHandlers></faultHandlers> <compensationHandlers></compensationHandlers> <eventHandlers></eventHandlers> (activities)* </process>

  13. BPEL Process <process name="NCName" targetNamespace="anyURI" queryLanguage="anyURI"? expressionLanguage="anyURI"? suppressJoinFailure="yes|no"? exitOnStandardFault="yes|no"? xmlns="http://docs.oasis-open.org/wsbpel/2.0/process/executable"> </process>

  14. PartnerLinkType • Characterizes the conversational relationship between two services • Define the roles played by each of the services in the conversation <plnk:partnerLinkType name="BuyerSellerLink"> <plnk:role name="Buyer" portType="buy:BuyerPortType" /> <plnk:role name="Seller" portType="sell:SellerPortType" /> </plnk:partnerLinkType>

  15. PartnerLinkType Seller Buyer Seller Buyer Invoke Seller Invoke Seller Send response to Buyer’s Callback Process Partner Service Process Partner Service Sync Async

  16. PartnerLinks • Define the relationship between the participating web services ( partners ) and the business process • myrole “business process’s role” • partnerRole “partner service’s role” • Associates interfaces (WSDL ports) with roles, using PartnerLinkTypes

  17. Partner Links

  18. Partner Link • Partner Link Associates with a partner link type <partnerLinks> <partnerLink name=“BuyerSellerPL” partnerLinkType=“BuyerSellerLink” myRole=“Buyer” partnerRole=“Seller”/> </partnerLinks> • Defines which role should be played by the process itself and the partner service

  19. Variables • Variables used by the process to keep the state • Statically typed via • WSDL Message Types • XML Schema Types • XML Schema elements • Variables can be “global” to the process or “local” to the scope

  20. Variables • Assigning values to variables • When message is received from a partner • Manipulate variables inside <assign> activity • Require knowledge about Xpath , XSLT

  21. Activities • Activities perform the process logic • Basic Activities • describe elemental steps in the process behavior • Structured Activities • control-flow logic • may contain other basic or structured activities

  22. Basic Activities • Receive • Reply • Invoke • Assign • Empty • Compensate • Catch • Throw • Rethrow • Exit

  23. Receive • Receive messages from an external party • Could be an external partner or the initiator of the business process • Acts as the entry point to the process. • Associated with • PartnerLink with MyRole • WSDL operation • Variable for the incoming message • createInstance=“yes” to create a new process instance. Otherwise, the message will be consumed by an already running process instance

  24. Reply • Sends the response back to the client • Always relates to a “receive” activity • Associated with • Same PartnerLink for the “receive” • Same operation for the “receive” • Variable for the output message

  25. Invoke • Used to consume (invoke) partner services • Associated with • PartnerLink with at least a “partnerRole” • WSDL operation of the partner service • Input variable • Output variable, if the operation is request-response

  26. Assign • Used to manipulate variables

  27. Initializing Variables • Variables contain a piece of XML • Manipulated using XPath • XPath is evaluated on XML • Avariable should be initialized before copying values to the internal elements.

  28. Expected Content • echoRequest= <p:echoStringxmlns:p="http://echo.services.core.carbon.wso2.org"> <in>HelloWorld</in> </p:echoString> • First we should initialize the variable ‘echoRequest’ before copying the string value “HelloWorld” to it. • $echoRequest/p:echoString/in

  29. Structured Activities • Sequence • While • Pick • Flow • Scope • If • ForEach • RepeatUntil • Compensate • Link

  30. Sequence • Used to define a set of activities to be executed in a strict ordered sequence • Can contain both basic and structured activities nested to arbitrary depth <sequence standard-attributes> standard-elements activity+ </sequence> • Contained activities are executed in the order they are defined • Completes when the last activity has completed

  31. Sequence

  32. Flow • Used to define a set of activities that will execute concurrently • Further allows synchronization of dependencies between activities • When one activity finishes, another activity starts • Directly nested activities are started concurrently as soon as the flow activity is started • Flow activity completes when all nested activities complete

  33. Flow

  34. If • Used to express a service of alternative choices of which exactly one is executed • Primary conditional branch specified by condition element • followed by • Unlimited number of elseif branches • Each with its own condition expression • One else branch

  35. If

  36. Looping • Looping executes a subset of the process multiple times in a controlled manner • ForEach • repeatUntil • while

  37. ForEach

  38. While

  39. RepeatUntil

  40. Pick • Waits for the occurrence of exactly one event from a set of events.

  41. Pick • Used to have the process wait until one of a set of events is triggered • Message events via onMessage element • Alarm events via onAlarm element • Can be used to initiate a process instance • If createInstance=“yes” , a new process instance is create upon the reception of one of a set of possible messages • Each on message is equivalent to a receive activity with the createInstance=“yes” • No alarms are permitted in the case

  42. Scope • Used to group activities into logically organized sections • Encapsulates a possibly compensatable, recoverable unit of work • Provide processing context for • Variables • PartnerLinks • FaultHandlers and Compensation handlers

  43. Scope

  44. Developing BPEL Process

  45. Contents of a BPEL Package • Process definition file ( .bpel file ) • Related WSDL files • Process deployment descriptor ( deploy.xml ) • Optional files • Unified endpoint files ( .epr ) • Service QOS file (services.xml) • XSL files

  46. Deploy.xml

  47. HelloWorld Sample • Generate a Synchronous BPEL Process using Developer studio wizard • Implement ‘assign’ Logic

  48. Invoking an External Partner

  49. Invoking a Partner Service • Generate BPEL process using the synchronous process template • Add an invoke activity with two assign activities • Create a PartnerLink and PartnerLinkType • Use echo service that comes with the BPS as the external service • Deploy and execute the process

  50. Invoking a Partner Service

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