MTAT Enterprise System Integration. Lecture 10. Process-Centric Services: Design & Implementation

Size: px

Start display at page:

Download "MTAT Enterprise System Integration. Lecture 10. Process-Centric Services: Design & Implementation"

Christine Norman
5 years ago
Views:

MTAT.03.229 Enterprise System Integration Lecture 10.

1 MTAT Enterprise System Integration Lecture 10. Process-Centric Services: Design & Implementation Marlon Dumas marlon. dumas ät ut. ee

2 SOA Lifecycle Solution Architect Service & Process Design Service & Process Implementation Developer Tester Service & Process Analysis Testing & Deployment Business Analyst Opportunity & Issue Identification Operation & Monitoring Administrat or 2 2 / 112

3 Recall Order Management Scenario 3

4 Recall Order Management Scenario warehouse sales customer finance 4

5 Let s have a look inside Supplier 5

6 Process-Centric Service Design: Concepts Interaction: information exchange between two services; involves one or more communication tasks on each side. Communication action Send message Receive message Internal action Data transformation/manipulation, Invocation to an unit of processing (e.g. provided by a component 6

7 Viewpoints in Process-Centric Service Design Choreography Global model of the interactions between two or more services. No preferred party Only interactions, no internal actions Interface (Behavioural and Structural) Model of the interactions between a service and one or several other services; Only interactions, no internal actions Orchestration Model of the interactions and internal actions that a (composite) service needs to undertake to achieve a goal. 7

8 Choreography 8

9 Behavioural Interface (Order Management) 9

10 Orchestration (Order Management) 10

11 Process-Centric Service Design Methods Choreography-driven Service Design Design a choreography in collaboration with my partners; Determine which interactions in the choreography involve me; Derive the behavioural interfaces I need to implement; Implement the behavioural interfaces. Orchestration-driven Service Design Define an orchestration and find appropriate services to plug into it (these two steps can be done in either order); Derive a behavioural interface from the orchestration; Expose this interface to the outside world. In some cases, mismatches can occur 11

12 Provided vs. Required Interfaces Buyer B's provided Buyer ("as is") B interface Purchase Order Choreography Buyer B's required ("to Buyer be") A interface SND Purchase Order RCV Order Response End Seller SND Purchase Order RCV Order Response No End All Responses Yes Received? 12

13 Choreography & Orchestration: Summary choreography... required interface provided interface Adaptation Adaptation Adaptation orchestration Internal service/api 13

14 BPEL Business Process Execution Language (BPEL) Domain-Specific Language for implementing process-centric services (orchestrations) XML Syntax, but vendors provide visual notations, e.g. Oracle SOA Suite ActiveVOS IBM WebSphere (dialect) Windows Workflow Foundation (dialect) Alternative: BPMN

15 Why BPEL? One could implement process-centric services in Java or C# 15

16 Why BPEL (cont.) But instead of hard-coding important business processes in application code we put it under the control of a BPM system Facilitates: Modification Reconfiguration Optimization Graphical tools can be used to visualize process flow 16

17 BPEL Overview At its core, BPEL is an imperative programming language: scoped variables assignment sequence while if then else exception handlers (throw / catch) 17

18 BPEL overview (cont.) BPEL offers few features specific to WS programming: XML variable typing (XML Schema or WSDL) expressions can be written in XPath/XSL Message send and receive actions parallelism and synchronisation Race conditions (e.g. message competing with a timer) multiple sequential or concurrent executions of a block (foreach) 18

WSDL Message receive exit Variables invoke

throw rethrow compensate compensatescope wait

partner link Port Type 1 Partner Links Partner

extensionactivity receive invoke invoke flow

Activities repeatuntil scope foreach if-else

handler Handlers compensation handler fault

19 WSDL Message receive exit Variables invoke assign validate reply empty Basic Activities throw rethrow compensate compensatescope wait 42 XML Schema Type XML Schema Element MyProcess partner link Port Type 1 Partner Links Partner Link Type partner link Port Type 2 receive extensionactivity receive invoke invoke flow pick invoke sequence while Structured Activities repeatuntil scope foreach if-else Properties Correlation Sets event handler event handler Handlers compensation handler fault handler fault handler termination handler Property 1 F. Casati et al. Property 2 19

20 BPEL Data Model: Variables Scoped variables typed as WSDL messages or XML Schema elements/types Activities input and output kept in scoped variables receive assign invoke Assignment activities move data around 0 reply 1 F. Casati et al

21 Partner Links Partner link: instance of typed connector Partner link type specifies required and/or provided porttypes (NOT the actual service) Channel along which a peer-to-peer conversation with a partner takes place Process 1 Port Partner Port Process 2 Type 1 Link Type Type 2 F. Casati et al. 21

22 Partner Links Process purchaseorderprocess purchaseorder PT PartnerLink purchasing I declare what I need and what I offer PartnerLink invoicing PartnerLink shipping PartnerLink scheduling computepricept invoicecallbackpt shippingpt shippingcallbackpt schedulingpt F. Casati et al. 22

23 Basic Activities receive Do a blocking wait for a matching message to arrive reply invoke assign Send a message in reply to a formerly received message Invoke a one-way or request-response operation updates values of variables or partner links F. Casati et al. 23

24 Receive <receive partnerlink="purchasing" porttype="lns:purchaseorderpt" operation="sendpurchaseorder" variable="po" createinstance="yes"> <documentation>receive Purchase Order</documentation> </receive> F. Casati et al. 24

25 Reply <reply partnerlink="purchasing" porttype="lns:purchaseorderpt" operation="sendpurchaseorder" variable="invoice"> <documentation>invoice Processing</documentation> </reply> Receive+Reply request/response F. Casati et al

26 Invoke <invoke partnerlink="shipping" porttype="lns:shippingpt" operation="requestshipping" inputvariable="shippingrequest" outputvariable="shippinginfo"> <documentation>decide On Shipper </documentation> </invoke> For one-way message sending, outputvariable is omitted F. Casati et al. 26

27 More Basic Activities wait Wait for a given time period or until a certain time has passed exit Immediately terminate execution of a business process instance <wait> <until>' t18:00+01:00'</until> </wait> <wait> <for> P1Y10M28DT10H37M46S </for> </wait> F. Casati et al. 27

28 BPEL Structured Activities flow sequence while repeatuntil Contained activities are executed in parallel, partially ordered through control links Contained activities are performed sequentially in lexical order Contained activity is repeated while a predicate holds Contained activity is repeated until a predicate holds pick foreach if then else scope Block and wait for a suitable message to arrive (or time out) Contained activity is performed multiple times sequentially or concurrently Select exactly one branch of activity from a set of choices (also called switch in BPEL 1.1) Associate contained activity with its own local variables, fault handlers, compensation handler, and event handlers D. Koenig 28

29 Nesting of Activities <sequence> <receive.../> <flow> <sequence> <invoke.../> <while... > <assign>...</assign> </while> </sequence> <sequence> <receive.../> <invoke... > </sequence> </flow> <reply> </sequence> receive sequence invoke while assign sequence flow sequence receive invoke reply D. Koenig 29

30 Sequence sequence <sequence> <wait> <until>' t18:00+01:00'</until> </wait> <invoke partnerlink="callserver" porttype="automaticphonecall" operation="texttospeech" inputvariable="seasongreetings" /> </sequence> F. Casati et al. 30

31 if then else If then else <if xmlns:inventory=" xmlns:flt=" <condition> bpel:getvariableproperty('stockresult','inventory:level') > 100 </condition> <flow>  </flow> <elseif> </elseif> <else> <throw faultname="flt:itemdiscontinued" /> </else> </if> 31

32 Loops while repeatuntil foreach <while> <condition>$orderdetails > 100</condition> <scope>...</scope> </while> <foreach countername="po > <startcountervalue>1</startcountervalue> <finalcountervalue> count($purchaseorder/itemslist/*) </finalcountervalue> <scope> </scope> </foreach> 32

33 Scopes and Handlers Scope Local variables Local partner links Local correlation sets Set of activities (basic or structured) Handlers Event handlers Message events or timer events (deadline or duration) Fault handlers Dealing with different exceptional situations (internal faults) Compensation handler Undoing persisted effects of already completed activities Termination handler Dealing with forced scope termination (external faults) variables partner links scope correlation sets... event handlers fault fault handlers handler compensation handler termination handler D. Koenig 33

34 Human Tasks Executable Business Process (BPEL) A1 A2 Human Task Handling Service A4 A3 Service A1 Service A2 Service A3 Service A4 Service Bus / Container App1: COBOL App2: PL1 App3: Java App4: C# 34

35 References and Acknowledgments This lecture material is based on: R. Khalaf et al.: The Business Process Execution Language for Web Services. Chapter 13 of Process-Aware Information Systems, John Wiley & Sons, 2005 Some slides taken from lecture material by Fabio Casati, with permission 35

Enterprise System Integration. Lecture 10: Implementing Process-Centric Composite Services in BPEL

Enterprise System Integration. Lecture 10: Implementing Process-Centric Composite Services in BPEL MTAT.03.229 Enterprise System Integration Lecture 10: Implementing Process-Centric Composite Services in BPEL Marlon Dumas marlon. dumas ät ut. ee Questions about reading material Week 8: Zimmermann, Doubrovski,