1、SOA & BPEL: Building a Service With BPEL and the Java EE Platform,Agenda,This session describes how developers using Java Platform, Enterprise Edition can create composite applications using BPEL with current Java EE tools and application servers that support Java Business Integration,Agenda,Why Ser
2、vices Why Composite Applications BPEL in the Mix A Java EE Based Composite Application Summary,Why Services?,SOA = an architectural principle for structuring systems that SOA emphasizes the de-coupling of system components New services are created from existing ones in a synergistic fashion Strong s
3、ervice definitions are critical Services can be subsequently re-composed in response to changing business requirements,What Are Services?,A function accessed using XML message exchange Message exchanges have well known exchange patterns Services are self-describing, usingmetadata (WSDL),What Does a
4、Service Do?,Transform dataRoute messagesQuery databasesOrchestrate conversationsApply business logicApply business policyHandle business exceptionsSolicit approvals,How Is a Service Implemented?, XSLT Enterprise JavaBeans (EJB) technology BPEL SQL XQuery Routing table Business rules EDI transform ,S
5、ervice Oriented Architecture,In April 2006 the Object Management Groups (OMG) SOA Special Interest Group adopted the following definition for SOAService Oriented Architecture is an architectural style for a Community of providers and consumers of services to achieve mutual value, that Allows partici
6、pants in the communities to work together with minimal co-dependence or technology dependenceSpecifies the contracts to which organizations, people and technologies must adhere in order to participate in the communityProvides for business value and business processes to be realized by the communityA
7、llows for a variety of technologies to be used to facilitate interactions within the community,Service Oriented Architecture,In March 2006 the OASIS group SOA Reference Model released its first public review draft. This defines the basic principles of SOA that apply at all levels of a service archit
8、ecture, from business vision through to technical and infrastructure implementationService Oriented Architecture; a paradigm for organizing and utilizing distributed capabilities that may be under the control of different ownership domains. It provides a uniform means to offer, discover, interact wi
9、th and use capabilities to produce desired effects consistent with measurable preconditions and expectations,Principles of SOA,Services share a formal contractServices are loosely coupledServices abstract underlying logicServices are composableServices are reusableServices are autonomousServices are
10、 statelessServices are discoverable,Benefits of SOA,Flexible (Agile) ITAdaptable to changing business needsFaster time to marketReuse existing code, minimize new developmentBusiness and process-drivenNew business opportunitiesGreater ROILeverage existing IT asset,Composite Applications,Composite app
11、lications are.applications!Comprised of heterogeneous parts Some existing parts Some new parts Composite applications != SOA Composite applications employ SOA principles Features exposed as Web services Standards-based interaction between services Described by standards-based artifacts Are themselve
12、s composable,Purchase Service,Purchase Service Functions,Composite ApplicationsSummary,A composite application is a collection of existing and independently developed applications and new business logic, orchestrated together into a brand new solution of a business problem that none alone can solve
13、Such an application looks to the user like a regular new interactive application, yet in reality it may be only 10 percent new and 90 percent an assembly of pre-existing components or data; The “glue” that brings a composite application together is integration technology,WS-BPEL Works With WSDL Web
14、Services Business Process Execution Language,Web services are described in WSDL Operations are message exchanges Each operation represents an individual unit of actionWe need a way to orchestrate these operations with multiple web services in the right order to perform a Business process Sequencing,
15、 conditional behavior etc. BPEL provides standard-based orchestration of these operations,What is BPEL?,XML-based language used to specify business processes based on Web ServicesBPEL processes describe Long running, stateful, transactional, conversations between two or more partner web servicesBPEL
16、 is key to implementing SOA Big Rules Conversational Mostly Async XML Document-based Orchestrated,BPEL Is a Web Service Sequencing Language,Process defines “conversation” flow chart Conversation consists of only WSDL-described message exchanges BPEL provides and consumes WSDL defined services Proces
17、s instance is a particular conversation following the chart Execution systems can support multiple concurrent conversations,BPEL “Fixes” WSDL,WSDL: unordered set of operationsOperations are message exchanges Need rules for ordering Support for sequencing Support for concurrency Choreography with ext
18、ernal entities,Orchestration vs. Choreography,OrchestrationAn executable business process describing a flow from the perspective and under control of a single endpoint (commonly: Workflow)BPEL handles Orchestration Choreography (WSDL) The observable public exchange of messages, rules of interaction
19、and agreements between two or more business process endpoints WSDL handles Choreography,BPEL: Relationship to Partners,Business Process Needs To.,Co-ordinate asynchronous communication between services Correlate message exchanges between parties Implement parallel processing of activities Implement
20、compensation logic(Undo operations),Manipulate/transform data between partner interactions Support for long running business transactions and activities Handle exception handling Need for universal data model for message exchange,BPEL Document Structure,BPEL Activities,Basic Activities ,Structured A
21、ctivities ,BPEL: Basic Activities,To invoke a one-way or request/response operation on a portType offered by a partnerTo do a blocking wait for a matching message to arriveCan be the instantiator of the business processTo send a message in reply to a message that was received through a The combinati
22、on of a and a forms a request-response operation on the WSDL portType for the process,BPEL: Basic Activities,Can be used to update the values of variables with new dataGenerates a fault from inside the business processAllows you to wait for a given time period or until a certain time has passedAllow
23、s you to insert a “no-op“ instruction into a business processThis is useful for synchronization of concurrent activities, for instance,BPEL: Structured Activities, Perform activities in sequential order Perform activities in parallel Conditional choice of activities Enclose multiple activities in a
24、single scope,Example Business Process,Sample Activities in BPEL,BPEL: Relationship to Partners,Why Do You Care on BPEL?, In SOA-enabled environment, you are more likely to build an application by orchestration various services via BPEL You will probably use BPEL design tool to create a BPEL document
25、 The BPEL document is then executed by BPEL engineHighly likely in JBI enabled platform,Example Scenario The Loan Processing Composite Application,WSDL: Schema Types (1) LoanProcessor.wsdl,WSDL: Schema Types (1) LoanProcessor.wsdl,BPEL Header,BPEL: Partner Links & Variables,BPEL: Partner Links & Var
26、iables,BPEL: the Decision,BPEL: the Decision, Reply,Loan Processor Service (EJB 3),What Are the Artifacts?,Service Consumption (Java APIs) for XML Web Services (JAX-WS 2.0),Runtime: Java EE Platform and Java Business Integration,Java Business Integration serves as messaging infrastructure Java EE we
27、b services interact through Java Business Integration Java Business Integration bindings allow remote consumers and providers Add other service technologies as Java Business Integration components Transparent to programmer using Java EE technology Reuse without re-coding,Java Business Integration (J
28、SR 208),Web Service Orchestration,Author, design, deploy and test business processes with the BPEL Designer Supports the BPEL 2.0 constructs Adds powerful methods for visual authoring Step through debugging support Built in testing capability for unit testingBPEL Mapper for BPEL variable assignments
29、Quickly generate XPath expressionsDeploy to the built in BPEL engine Running as a service engine in the JBI environment within the provided Sun Java System Application Server,Summary,SOA enables flexible and agile enterprise application architecture Services can be created and used using a variety o
30、f Java EE technologies BPEL is a service orchestration language for creating stateful composite applications Services can be re-implemented using other technologies as long as service interface is preserved without changing consumers Java Business Integration is the enabling infrastructure,Questions?,
