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WS-BPEL 2.0 Web Services Business Process Execution Language Workshop Dieter König, IBM Senior Technical Staff Member

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Presentation on theme: "WS-BPEL 2.0 Web Services Business Process Execution Language Workshop Dieter König, IBM Senior Technical Staff Member"— Presentation transcript:

1 WS-BPEL 2.0 Web Services Business Process Execution Language Workshop Dieter König, IBM Senior Technical Staff Member Charlton Barreto, Adobe Senior Computer Scientist/Architect

2 WS-BPEL 2.0 MyProcess invoke receive invoke Handlers fault handler event handler fault handler compensation handler termination handler event handler Partner Links Partner Link Type Port Type 1 Port Type 2 partner link partner link Variables 42 WSDL Message XML Schema Type XML Schema Element Properties Correlation Sets Property 1 Property 2 Structured Activities if-else while scope pick sequence flow repeatUntil forEach Basic Activities receive reply invoke throw exit wait empty compensatevalidate assign rethrow extensionActivity compensateScope

3 Abstract Business Processes not only play a key role in Business-to-Business (B2B) and Enterprise Application Integration (EAI) scenarios by exposing the appropriate invocation and interaction patterns but they are the fundamental basis for building heterogeneous and distributed applications (workflow- based applications). Web Services Business Process Execution Language (WS-BPEL) provides the language to specify business processes that are composed of Web services as well as exposed as Web services. Business Processes specified via WS-BPEL are portable; they can be carried out by every WS-BPEL compliant execution environment. This presentation gives an overview of the WS-BPEL language and shows how it can be used to compose Web services. It provides highlights of WS- BPEL, including structured activities, correlation, compensation, and fault handling. Finally, the OASIS WS-BPEL Technical Committee work, the current status of the standard, and an outlook on follow-on activities is presented.

4 WS-BPEL 2.0 n Motivation n OASIS and WS-BPEL n Main Concepts n Examples n Status and support

5 n Integration continues to be a key problem facing businesses l Intra-enterprise integration (Enterprise Application Integration) l Integrating with partners (Business-to-Business Integration) l Syndication n Web services  move towards service-oriented computing l Applications are viewed as “services” l Loosely coupled, dynamic interactions l Heterogeneous platforms l No single party has complete control n Service composition l How do you compose services in this domain? Motivation

6 Integration

7 n BPEL processes can automate both simple and complex interactions between Web services l Supporting long running business transactions l Correlating message exchanges l Implementing parallel processing of activities l Mapping data between partner interactions l Providing consistent exception and recovery handling Concerns addressed by BPEL

8 Why the Need For BPEL? n WSDL defined Web services have a stateless interaction model l Messages are exchanged using n Synchronous invocation n Uncorrelated asynchronous invocations n Most “real-world” business processes require a more robust interaction model l Messages exchanged in a two-way, peer-to-peer conversation lasting minutes, hours, days, etc. n BPEL provides the ability to express stateful, long-running interactions

9 n Programming in the large l Non-programmers implementing flows n Flow logic deals with combining functions in order to solve a more complex problem (such as processing an order) n Programming in the small l Programmers implementing functions n Function logic deals with a discrete fine-grained task (such as retrieving an order document or updating a customer record) Two programming models

10 n Aiming for a single approach for both l Executable processes n Contain the partner’s business logic behind an external protocol l Abstract processes n Define the publicly visible behavior of some or all of the services an executable process offers n Define a process template embodying domain- specific best practices Process Usage Patterns

11 n Portability and Interoperability n Flexible Integration l Rich, and easily adaptable to changes in underlying services n Recursive, type-based composition, enables l Third-party composition of existing services l Providing different views on a composition to different parties l Increased scalability and reuse n Stateful conversations and lifecycle management l Supports multiple stateful long-running conversations n Recoverability l Long running business processes need fault handling and compensation mechanisms to manage and recover from errors Process Model Requirements

12 n Industry standard language for expressing business processes l Leverage a common skill set and language n Designed to fit naturally into the Web services stack l Expressed entirely in XML l Uses and extends WSDL 1.1 l Uses XML Schema 1.0 for the data model n Portable across platform and vendor l Will run on any BPEL-compliant engine n Interoperable between interacting processes l Layering on top of Web services stack Benefits of BPEL

13 n BPEL is the Web Services Orchestration standard from OASIS l beepel’, beep’uhl, bip’uhl n An XML-based grammar for describing the logic to orchestrate the interaction between Web services in a business process BPEL Historical Timeline Dec 2000 Microsoft publishes XLANG March 2001 IBM publishes WSFL July 2002 IBM, Microsoft and BEA converge WSFL & XLANG into BPEL4WS 1.0 March 2003 BPEL4WS is submitted to OASIS May 2003 OASIS publishes BPEL4WS st H 2007 WS-BPEL 2.0 released BPEL Historical Timeline Dec 2000 Microsoft publishes XLANG March 2001 IBM publishes WSFL July 2002 IBM, Microsoft and BEA converge WSFL & XLANG into BPEL4WS 1.0 March 2003 BPEL4WS is submitted to OASIS May 2003 OASIS publishes BPEL4WS st H 2007 WS-BPEL 2.0 released WS-BPEL 2.0

14 WS-BPEL XML, Encoding Other protocols Other services Transport and Encoding Business Processes WSDL, Policy, UDDI, Inspection Description Security Reliable Messaging Transactions Coordination SOAP (Logical Messaging) Quality Of Service You are here WS-BPEL in the WS-* Stack

15 WS-BPEL 2.0 n Motivation n OASIS and WS-BPEL n Main Concepts n Examples n Status and support

16 Getting the Players Together BPEL 1.1 (*) (*) BPEL 1.1 authors, May 2003 WS-BPEL 2.0

17 OASIS Technical Committee n Charter of the WS-BPEL Technical Committee l Standardize … n Common concepts for a business process execution language for usage patterns including both the process interface descriptions and executable process models l Explicitly do not address … n Bindings to specific hardware/software platforms and other mechanisms required for a complete runtime environment for process implementation n > 280 committee members, including observers ~ 30 active voting members, attending weekly calls n Issues Process l List of all issues available at (original list - completed) (public review list)

18 WS-BPEL Design Goals n Business processes defined using an XML-based language n Web services are the model for process decomposition and assembly n The same orchestration concepts are used for both the external (abstract) and internal (executable) views of a business process n Both hierarchical and graph-like control regimes are used, reducing the fragmentation of the process modeling space n An identification mechanism for process instances is provided at the application message level n The basic lifecycle mechanism is in implicit creation and termination of process instances. n A long-running transaction model is defined to support failure recovery for parts of long-running business processes n Language built on compatible Web services standards in a composable and modular manner

19 WS-BPEL 2.0 n Motivation n OASIS and WS-BPEL n Main Concepts n Examples n Status and support

20 WS-BPEL Language Structure n Process n Partner links n Data handling n Properties and correlation n Basic and structured activities n Scopes

21 WS-BPEL Process Definition process imports Declare dependencies on external XML Schema or WSDL definitions extensions Declare namespaces of WS-BPEL extension attributes and elements variables Data holding state of a business process or exchanged with partners partner links Relationships that a WS- BPEL process will employ in its behavior correlation sets Application data fields that together identify a conversation message exchanges Relationship between inbound and outbound message activities event handlers Concurrently process inbound messages or timer alarms fault handlers Deal with exceptional situations in a process primary activity Perform the process logic – any number of activities may be recursively nested XML schemas WSDL definitions

22 n BPEL is layered on top of and extends the WSDL service model l WSDL defines the specific operations allowed l BPEL defines how WSDL operations are orchestrated to satisfy a business process l BPEL also specifies extensions to WSDL in support of long-running asynchronous business processes WSDL 1.1 BPEL 2.0 BPEL-defined WSDL extensions Relationship with WSDL

23 Recursive Composition n BPEL processes interact with WSDL services exposed by business partners Web Service Loan Approval Process Web Service WSDL Loan Approval PortType Financial Institution‘s Web Service (Loan Approver) invoke Interfaces exposed by the BPEL process Interfaces consumed by the BPEL process receive reply

24 Composition of Web Services Partner Link Type Service PService AService B A’s WSDLP’s WSDLB’s WSDLF invoke receive invoke

25 Partner Links process partner link partner link type Peer-to-peer conversational partner relationship WSDL port type myRole Provided port type WSDL port type partnerRole Required port type receive Inbound request – service provided by the process invoke Outbound request – service required by the process

26 Variables process assign xsl:transform receive request response invoke request reply response 42 WSDL message WSDL message WSDL messages Variables defined using WSDL messages 42 XML schemas XML Schema elements / types Variables defined using XML schema elements or types

27 process Variable Properties XML schema element WSDL message part... property alias Typed properties are mapped (aliased) to parts of WSDL messages or XML schema elements property alias A property creates a name that has semantic significance beyond an XML schema type getVariableProperty( variable, property ) Properties isolate the process logic from the details of a variable definition 

28 process instance 3 process Properties and Correlation Sets correlation set customerId orderNumber process instance 1process instance 2 process instance 4 receive Submit purchase order How to identify stateful instances via stateless Web service interfaces? Messages in long-running conversations are correlated to the correct process instance locate purchaseOrder cId = 0815 orderNo = 42 receive Query order status queryOrderStatus custId = 0815 oNo = 42 customerId orderNumber 4(0815, 49) 3(0815, 42) 2(0707, 11) 1(0311, 33) initiate process instance 3

29 process Basic Activities receivereply invoke Invoke a one-way or request-response operation Do a blocking wait for a matching message to arrive / send a message in reply validate assign Update the values of variables or partner links with new data Validate XML data stored in variables throw rethrow Generate a fault from inside the business process Forward a fault from inside a fault handler exit Immediately terminate execution of a business process instance compensate compensateScope Invoke compensation on all completed child scopes in default order Invoke compensation on one completed child scope wait Wait for a given time period or until a certain time has passed empty No-op instruction for a business process extensionActivity Wrapper for language extensions

30 process flow Contained activities are executed in parallel, partially ordered through control links sequence Contained activities are performed sequentially in lexical order while Contained activity is repeated while a predicate holds repeatUntil Contained activity is repeated until a predicate holds pick Block and wait for a suitable message to arrive (or time out) forEach Contained activity is performed sequentially or in parallel, controlled by a specified counter variable if-elseif-else Select exactly one branch of activity from a set of choices scope Associate contained activity with its own local variables, partner links, etc., and handlers Structured Activities 2.N.1. … B C A c c c1c2 … 2.N.1. … … AM2M1

31 Nesting Structured Activities... receive reply receive invoke assign sequence flow while

32 process Scopes scope Scopes provide a context which influences the execution behavior of its enclosed activities Isolated scopes provide control of concurrent access to shared resources scope Local declarations – partner links, message exchanges, variables, correlation sets Local handlers – event handlers, fault handlers, a termination handler, and a compensation handler Compensation handler to undo persisted effects of already completed activities Termination handler to deal with forced scope termination (external faults) primary activity scope

33 Process Process Instance Lifecycle n Business processes defined in BPEL represent stateful Web services l When a process is started, a new instance is created according to the process definition l The creation and destruction of BPEL process instances is by design implicit receivereplyinvoke

34 WS-BPEL 2.0 n Motivation n OASIS and WS-BPEL n Main Concepts n Examples n Status and support

35 Graph-Oriented Authoring Style 1. A customer asks for a loan, providing name and amount info 2. Two services are involved: a) A risk assessor which can approve the loan if the risk is low b) A loan approver which checks the name and approves/disapproves the loan 3. The reply is returned to the customer invoke receive invoke reply assign loanApprovalPT loan approver riskAssessmentPT loan assessor amount < 10000amount >= risk = "high" risk = "low"approved = "true" approved = "false" flow

36 if buyer$$ < seller$$ else Structured Authoring Style reply (buyer) reply (seller) receive (buyer) receive (seller) assign "success" assign "failure" sequence flow if-else

37 scope event handler parallel forEach scope flow... scope event handler event handler event handler event handler event handler event handler event handler event handler event handler event handler Parallel Processing

38 compensation handler charge credit card refund customer ship goods fault handler notify manager compensate fault handler rethrow Process sequence scope Fault Handling & Compensation

39 Process BProcess A Dynamic Partner Link Assignment receive request invoke callback PortType-B PortType-A invoke service receive response Partner Link Type A-role B-role partner link partner link assign EPR assign EPR

40 Abstract & Executable Processes n Executable Processes l Contain the partner’s business logic behind an external protocol l Model actual behavior of a participant in a business interaction l Encompass enough detail to fully specify execution

41 Abstract & Executable Processes n Abstract Processes l Partially specified processes that are not intended to be executed l May hide some of the required concrete operational details l Serve a descriptive role l Used to guide executable processes l More than one possible use case

42 Travel Reservation - Example Abstract Process ViewExecutable Processes View get itinerary get order tickets receive confirmation confirm flight send tickets send confirmation submit to agent receive tickets receive confirmation select airline reserve seats charge credit card plan trip Agent ProcessAirline ProcessTraveler Process

43 Abstract Profiles n Profiles address varying requirements among Abstract Processes n Two profiles provided in WS-BPEL l Observable Behavior l Process Template

44 Abstract Profiles & Use Cases n Use cases l Constraints on message exchange n Specify order in which messages are consumed or produced l View on internal processes n Only projection of internal (executable) process is visible l Bridge model to executable n Provide hooks to executable for model definition to enable abstraction l Template as “best practice” n Specification of common activities, major data structures, and main control flow

45 WS-BPEL 2.0 n Motivation n OASIS and WS-BPEL n Main Concepts n Examples n Status and support

46 WS-BPEL n Portable, interoperable process model for long running business processes n Flexible integration of Web services l WSDL abstract interfaces alone used to define composition n Enables two levels of adaptive behavior Abstract partners can be bound to actual services at runtime The process can choose a protocol for communicating with the service at runtime l Services whose data definitions do not match can be composed n Data transformations can be inlined in process definition

47 Conditional behavior – if { elseif } [ else ] l Replacing the BPEL4WS 1.1 switch activity Repetitive execution – repeatUntil l Like BPEL4WS 1.1 while activity with at least one iteration Processing multiple branches – forEach l Sequential or parallel iteration controlled by a counter variable and a completion condition Reversing work – compensate and compensateScope l Compensate all child scopes or one specific child scope Propagating faults – rethrow l Rethrow the fault caught in a fault handler Validating data – validate l Explicit XML schema validation of WS-BPEL variable content l Validation also possible within assignment Immediately ending a process – exit l Replacing the BPEL4WS 1.1 terminate activity Adding new activity types – extensionActivity l Designated WS-BPEL extension point for new activity types What’s new since BPEL 1.1?

48 n Variable initialization l Inline within variable declaration n Partner links l Intent for partner role initialization n Locally declared messageExchange l Internal correlation of receive/pick/onEvent and reply activities n Correlation sets l Join behavior for multiple start activities n XML schema variables in Web service activities l Usability enhancement for WS-I compliant doc/lit-style WS interactions n Assignment l Clarification of copy behavior l Keep source element name l Ignore missing from data l Extension assign operation n XSLT for variable transformations New XPath extension function bpel:doXslTransform(...) n XPath access to variable data l XPath variable syntax $variable[.part]/location n Flow activity l Scope isolation and link semantics What’s new since BPEL 1.1?

49 n Fault handlers l XML schema typed fault variables l Exit on standard fault behavior n Compensation handlers l New scope snapshot semantics l Fault handling during compensation n Event handlers l Recurring events l Resolution of variable, partnerLink, messageExchange, correlationSet n Termination handler l Customize scope termination behavior n Import l Predefined import types WSDL and XSD n Extensibility l Global documentation element n Extension namespace declarations l Mandatory and optional extensions n Abstract processes l Common base (syntax) and profiles (semantics) l Opacity and omission of activities, expressions, attributes What’s new since BPEL 1.1?

50 WS-BPEL Adoption: Products n Active Endpoints ActiveBPEL Designer n Active Endpoints ActiveBPEL Enterprise Server n BEA WebLogic n bexee BPEL Execution Engine (open source) n Cape Clear Orchestrator n FiveSight Process eXecution Engine (PXE) n IBM WebSphere Studio Application Developer – Integration Edition n IBM WebSphere Business Integration – Server Foundation n IBM WebSphere Integration Developer n IBM WebSphere Process Server n Microsoft BizTalk Server n MidOffice BPEL Editor (open source) n MidOffice BPEL Engine (open source) n OpenLink Virtuoso Universal Server n OpenStorm ChoreoServer n Oracle BPEL Process Manager n Parasoft BPEL Maestro n SAP NetWeaver n SeeBeyond eInsight BPM n Twister (open source)

51 WS-BPEL Application Areas n Business Process Design n Autonomic Computing n Grid Computing n Semantic Web

52 WS-BPEL Schedule n Status (March 2007) l First and second public reviews completed l Approved Committee Specification submitted for standardization l Five organizations have certified use of WS- BPEL in product n ActiveEndpoints, IBM, Intalio, SEEBURGER, Sun

53 WS-BPEL Schedule n Next steps l OASIS standard - April 2007 n Voting opens March 19 and closes March 30 l OASIS Symposium - April 15-20, 2007 San Diego, California, USA n WS-BPEL Lightning Round - April 16 n Business Process Sessions - April 16 n WS-BPEL Workshop - April 18

54 WS-BPEL Follow-on Work n BPEL4People l Human user interactions n BPEL Subprocesses l Based on a coordination protocol n BPELJ l Inline Java code in activities and expressions n Currency with related standards l WSDL 2.0, XPath 2.0, XQuery, etc.

55 WS-BPEL Resources n WS-BPEL 2.0 – Committee Specfication (03/2007) n OASIS Technical Committee n Info aggregator sites l Wikipedia l BPEL Resource Guide n Numerous books and conference papers n Analyst reports n BPEL4WS 1.1 /


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