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Web Services Composition Technologies. 2. Agenda. IntroductionWSFLBPML/WSCIBPMLWSCIComparison. Web Services Composition Technologies. 3. How to tap the full potential of . Web servicesMultiple invocation between two or more servicesAll parties - Service providers and service clients. SER
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1. Web Service Composition Technologies A closer look at WSFL and BPML/WSCI
Katharina Siorpaes
katharina.siorpaes@deri.at
Next Web Generation Seminar SS04
DERI Innsbruck
2. Web Services Composition Technologies 2 Agenda Introduction
WSFL
BPML/WSCI
BPML
WSCI
Comparison
3. Web Services Composition Technologies 3 How to tap the full potential of … … Web services
Multiple invocation between two or more services
All parties - Service providers and service clients
4. Web Services Composition Technologies 4 WSFL Web Service Flow Language
By IBM
To fit into the WS Stack naturally
XML-based grammar to describe WS interactions
5. Web Services Composition Technologies 5 Web Services Stack
6. Web Services Composition Technologies 6 Multi-party business processes Operational description
? WSDL (Web Service Description Language)
Behavioural description
? WSEL (Web Service Endpoint Description Language)
Composition and choreography of WS
? WSFL (Web Service Flow Language)
7. Web Services Composition Technologies 7 Flow Composition in WSFL (I) Choreograph functionalities of a collection of WS
Logic of a business process
Specification of the execution sequences of the functionalities of services
8. Web Services Composition Technologies 8 Flow Composition in WSFL (II) Business tasks
Control flow
Data flow
9. Web Services Composition Technologies 9 Global Composition in WSFL Specification of interaction pattern of a collection of WS
No specification of execution sequence
Interactions between service providers and service requestors
Peer-to-peer interactions
Hierarchical interactions
10. Web Services Composition Technologies 10 BPML/WSCI ? Complementary efforts
Business Process Model Language
describes executable business processes
private
Web Services Choreography Interface
describes messages between collaborating web services
XML-based language for WS collaboration
Public interactions and choreographies between services
11. Web Services Composition Technologies 11 Web Service stack
12. Web Services Composition Technologies 12 BPML XML-based meta-language
Developped by Intalio, SUN, SAP, Versata, CSC, SeeBeyond (www.bpmi.org - Business Process Management Initiative)
Modeling collaborative and transactional business processes
Relying on a formal model
13. Web Services Composition Technologies 13 BPML – 5 elements Activities
performance of simple or complex functions
Processes
types of complex activities that define its own context
Contexts
environment for the execution of activities
Properties
information exchange within a context
Signals
coordination of activities
14. Web Services Composition Technologies 14 BPML key features basic activities for sending, receiving, and invoking services
handles conditional, sequential, and parallel activities
for Long-running processes supporting persistence
supports short and long-running transactions
robust exception handling mechanisms
Recursive composition
No automation support! Services and partners to be specified at design time
15. Web Services Composition Technologies 15 WSCI Defines overall choreography of WS taking part in an interaction
BEA Systems, BPMI.org, Commerce One, Fujitsu Limited, Intalio, IONA, Oracle Corporation, SAP AG, SeeBeyond Technology Corporation and Sun Microsystems.
Uses messages
No focus on the definition of executable business processes (that‘s what BPML does)
Direct correspondence to WSDL
Each WSCI unit of work ? WSDL operation
WSDL: entry points of each service
WSCI: interactions among WSDL operations
16. Web Services Composition Technologies 16 WSCI – key features (I) Support for basic activities:
each activity specifies the WSDL operation involved
use <action> to define a basic request/response message
use <call> to invoke external services
17. Web Services Composition Technologies 17 WSCI – key features (II) Support for structured activities:
sequential, parallel, and conditional looping
use <all> to specify a unordered actions to perform
Support for business transactions and exceptions:
transactional contexts can be defined in WSCI
any failure in a context will result in all transactions in context being rolled back
18. Web Services Composition Technologies 18 WSCI – concepts (I) Interface
Observable behaviour of a WS in a message exchange with other WS
Activities
Basic unit of behaviour; either atomic or complex (composed of other activities)
Processes
Top-level processes and nested processes
Properties
Reference a value within an IF definition
19. Web Services Composition Technologies 19 WSCI – concepts (II) Context
Environment: a set of activities is executed
Message correlation
Structure of conversations, management of multiple conversations with the partner
Exceptional behaviour
Alternative patterns of behaviour; association to activities
Transactional behaviour
Global model
Overall message exchange
20. Web Services Composition Technologies 20 BPEL4WS- BPML BPML is a strict superset of BPEL4WS
BPML and BPEL4WS share an identical set of idioms and similar syntaxes as the basis of convergence
BPML provides a rich and mature language for expressing both simple and complex business processes
21. Web Services Composition Technologies 21 BPEL4WS – BPML BPML and BPEL4WS are both block-structured languages, with the addition of nested processes in BPML
BPML is based on a logical process model that can fully express concurrent, repeating, and dynamic tasks
BPML builds on the foundation of WSCI for expressing public interfaces and choreographies
22. Web Services Composition Technologies 22 BPEL4WS – BPLM/WSCI WSCI/BPML has much richer choreography support and backing by W3C working group
BPEL4WS has major supporters behind it, with developer tools and documentation already available
23. Web Services Composition Technologies 23 BPEL4WS – BPLM/WSCI
24. Web Services Composition Technologies 24 References V.d. Aalst, W.M.P., Dumas, M., ter Hofstede, A.H.M., Wohed, P. (2002) Pattern-based analysis of BPML (and WSCI), http://xml.coverpages.org/Aalst-BPML.pdf
Cabera, F., Copeland, G., Freund, T., Klein J., Langworthy D., Orchard, D., Shewchuk, J., Storey, T. (2002) Web Service Coordination (WS-Coordination), http://www-106.ibm.com/developerworks/library/ws-coor/, 2002
Leymann, F. (2001) Web Services Flow Language (WSFL1.0), http://www-306.ibm.com/software/solutions/webservices/pdf/WSFL.pdf
Arkin, A., (2002) Business Process Modeling Language,
Arkin, A., Askary, S., Fording, S., Jekeli, W., Kawaguchi, K., Orchard, D., Pogliani, S., Riemer, K., Struble, S., Takacsi-Nagy, P., Trickovic, I., Zimek, S. (2002) Web Service Choreography Interface 1.0
25. Web Services Composition Technologies 25 Thanks for your attention!