1. 1 WS Technologies III BPEL4WS Roberto Bruni Dipartimento di Informatica Università di Pisa Models and Languages for Coordination and Orchestration IMT- Institutions Markets Technologies - Alti Studi Lucca

2. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 2 Models and Languages for Coordination and Orchestration Contents Orchestration and Choreography WSFL Transactions and Compensations BPEL4WS

3. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 3 Models and Languages for Coordination and Orchestration WS Composition and Transactions: Early Work eCo framework vague notion of orchestration created by CommerceNet to demonstrate the value of integrating e-commerce services focus on the document exchanges required for B2B integration WSCL (Web Services Conversation Language) somewhat analogous to web services choreography outlined a simple conversation language standard, focused on modeling the sequencing of interaction between web services

4. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 4 Models and Languages for Coordination and Orchestration WS Composition and Transactions: Early Work WSFL IBM proposal flow model for orchestration, global model for choreography allowed for recursive (de)composition supported handling of exceptions had no direct support for transactions XLANG developed by Microsoft for the Microsoft BizTalk Server provided block-structured support for sequential, parallel, and conditional process control flow included a robust exception handling facility had support for long-running transactions through compensation

5. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 5 Models and Languages for Coordination and Orchestration WS Composition and Transactions: WSCI Web Services Choreography Interface pronounced “Whiskey” proposed by Sun, SAP, BEA, and Intalio XML-based choreography language for WS collaboration abstract processes, not executable processes supports message correlation, sequencing rules, dynamic collaboration, exception handling and transactions only describes the observable behavior between WS each partner needs a single WSCI document a WSCI choreography includes a set of WSCI documents

6. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 6 Models and Languages for Coordination and Orchestration Business Process Management Language developed by Business Process Management Initiative (BPMI.org), chartered by Intalio, Sterling Commerce, Sun, CSC, and others initially designed to support executable business processes (over a BPMS), but the first draft also incorporated the WSCI protocol basic activities for sending, receiving, and invoking services structured activities that handle conditional choices, sequential and parallel activities, joins, looping, and scheduling of tasks at specific times other features include persistence, roles, instance correlation, and recursive decomposition WS Composition and Transactions: BPML

7. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 7 Models and Languages for Coordination and Orchestration WS Composition and Transactions: BPEL4WS Business Process Execution Language for Web Services promoted by IBM, Microsoft, and BEA supersedes XLANG and WSFL (but is far more complex) XML-based grammar, leveraging WSDL for describing the control logic abstract processes (called business protocols) executable processes (over an orchestration engine) includes support for both basic and structured activities mechanism for catching and handling faults (like Java) compensatory activities via compensation handler

8. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 8 Models and Languages for Coordination and Orchestration WS Composition and Transactions

9. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 9 Models and Languages for Coordination and Orchestration BTP (Business Transactions Protocol) emerging proposal by OASIS (Organization for Advance Structured Information Systems), involving HP, Oracle, BEA aimed to B2B transactions in loosely coupled domains (not specifically for WS) WS-Coordination by W3C describes how services can make use of pre-defined coordination contexts to subscribe to a particular role in a collaborative activity WS-Transaction by W3C provides a framework for incorporating transactional semantics into coordinated activities. WS Composition and Transactions

10. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 10 Models and Languages for Coordination and Orchestration Business Process Execution Language for Web Services BPEL4WS v1.1 (5 May 2003) released along with two others specifications: WS-Coordination and WS-Transaction block-structured language (like XLANG), allowing recursive blocks but restricting definitions and declarations to the top level activities as the basic components structured activities for sequential control include sequence, switch, and while also nondeterministic choice based on external events (pick) concurrency and synchronization between activities is provided by flow (like WSFL)

11. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 11 Models and Languages for Coordination and Orchestration BPEL4WS: Terminology Partners (service providers) a subset of the partner links of the process Partner links the services with which a business process interacts each partner link is characterized by a partnerLinkType Partner link type characterizes the conversational relationship between two services by defining the "roles" played by each of the services in the conversation and specifying the portType provided by each service to receive messages within the context of the conversation

12. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 12 Models and Languages for Coordination and Orchestration BPEL4WS: Terminology Variables provide the means for holding messages that constitute the state of a business process variables can also hold data that are needed for holding state related to the process and never exchanged with partners the type of each variable may be a WSDL message type, an XML Schema simple type or an XML Schema element

13. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 13 Models and Languages for Coordination and Orchestration BPEL4WS: Activities blocking wait for a matching message to arrive to send a message in reply to a message that was received through a the combination of a and a forms a request-response operation on the WSDL portType to invoke a one-way or request-response operation on a portType offered by a partner

14. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 14 Models and Languages for Coordination and Orchestration BPEL4WS: Activities to update the values of variables with new data copying data from one variable to another is a common task within a business process a single construct can contain any number of elementary assignments this activity can also be used to copy endpoint references to and from partner links

15. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 15 Models and Languages for Coordination and Orchestration BPEL4WS: Activities to generate a fault from inside the business process to wait for a given time period or until a certain time has passed nil activity (useful for synchronization of concurrent activities)

16. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 16 Models and Languages for Coordination and Orchestration BPEL4WS: Activities to define a collection of activities to be performed sequentially in lexical order to select exactly one branch from a set of choices to indicate that an activity is to be repeated until a certain success criteria has been met

17. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 17 Models and Languages for Coordination and Orchestration BPEL4WS: Activities to block and wait for a suitable message to arrive or for a time-out alarm to go off when one of these triggers occurs, the associated activity is performed and the pick completes to specify one or more activities to be performed concurrently links can be used within concurrent activities to define arbitrary control structures, but with great care ex. a link MUST NOT cross the boundary of a while activity, a serializable scope, an event handler or a compensation handler

18. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 18 Models and Languages for Coordination and Orchestration BPEL4WS: Activities to define a nested activity with its own associated variables, fault handlers, and compensation handler to invoke compensation on an inner scope that has already completed normally can be invoked only from within a fault handler or another compensation handler

19. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 19 Models and Languages for Coordination and Orchestration BPEL4WS: Other Features Message correlation (like WSCI) Transition and join conditions dead path elimination Fault handlers Compensation handlers Event Handlers Serializable scopes...

20. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 20 Models and Languages for Coordination and Orchestration It’s Not a Stack, It’s a Web of Dependencies WS-Coordination WS-Transaction WS-Addressing WSDL 1.1 WS-SecureConversation Xpath 1.0 XML Schema 1.0 XML 1.0 XML Infoset XML Namespaces XML Encryption X.509 WS-Trust WS-Policy WS-Routing A Partial View (  Gartner) BPEL 1.1 WS-ReliableMessaging WS-Security XML Signature SOAP 1.2 WS-PolicyAssertions WS-SecurityAddendum WS-SecurityPolicy WS-PolicyAttachments

21. Roberto Bruni @ IMT Lucca 23 March 2005 Institutions Markets Technologies IMT 21 Models and Languages for Coordination and Orchestration Vendor Landscape BEA WebLogic Workshop while BEA contributed to both the BPEL4WS and WSCI initiatives, it does not provide native support for either standard Collaxa Orchestration Server supports BPEL4WS, WS-Coordination, WS-Transaction IBM BPWS4J Java runtime platform for BPEL + editor Sun WSCI Editor supports WSCI (in pat), not BPEL