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WS Orchestration Eyal Oren DERI 2004/04/07

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Presentation on theme: "WS Orchestration Eyal Oren DERI 2004/04/07"— Presentation transcript:

1 WS Orchestration Eyal Oren DERI 2004/04/07

2 Eyal Oren2 Survey of WS orchestration definitions & requirements survey of standards –BPEL4WS –BPML –WSCI survey of vendors

3 Eyal Oren3 Definitions orchestration –executable process (that interacts with other web services) –control from the perspective of one business partner –for implementation –workflow choreography –sequence of messages –public message exchanges –for collaboration –protocols this is the private process, our orchestration is subset of this this is like our choreography

4 Eyal Oren4 Requirements a-synchronicity –need message correlation: identifying returning calls exception management –services (operations) throw & catch exceptions compensating transactions –resource locking not feasible reusable composition: –separation process logic – used web services –don’t understand, looking for hierarchy? goal – capability separation web service – capability separation we need to have this

5 Eyal Oren5 Standards overview BPEL4WS –describes (control logic for) coordination of web services –Microsoft, IBM, BEA (XLANG & WSFL) –execution environment (BPWS4J) –not considered by W3C : not royalty-free BPML –describes executable business processes –Intalio, Sun, …, WSCI –describes messages between collaborating web services –Sun, SAP, BEA, Intalio

6 Eyal Oren6 Standards relation

7 Eyal Oren7 BPEL4WS (1) (control logic for) coordination of web services abstract processes: –choreography –public message exchange executable processes: –orchestration –private workflow on top of WSDL

8 Eyal Oren8 BPEL4WS (2) primitive activity (input & input-output operations) –invoke (an operation on a web service) –receive (waiting for invocation) –reply(responding, in input/output operation) –wait(for … time) –assign(copy & compute data to variables) –throw(exception) –terminate(stop service instance) –empty structure activity (control flow) –combines primitives using: sequence, branch, loop, pick, flow –need more time to investigate possibilities

9 Eyal Oren9 BPEL4WS (3) (WSDL defines messages, operations, porttypes) link –describes conversation between two roles –(specifies porttype of service, to receive messages) –multiple messages can be exchanged during conversition –partner: web service with role in linktype business process: list of activities (with partners) actual web service grounding can be dynamic –unclear yet (WS-Adressing) –BPWS4J uses hard-wired at deploy we need this too (as Axel said on wsmo-d)

10 Eyal Oren10 BPML language for describing business processes simple activity –action, assign, call, compensate, delay, fault, synch complex activity –all, choice, foreach, sequence, switch, until, while transaction support (compensation, nesting) exception handling (throw, timeout)

11 Eyal Oren11 WSCI language for describing web services collaboration message correlation sequencing rules –basic: call, delay, empty, fault, spawn, join –complex: all, choice, foreach, sequence, switch, until, while –but cannot specify input/output exception handling transactions is this really only public message exchange then?

12 Eyal Oren12 Comparison BPEL4WS – BPML+WSCI intentions are the same no comparison in the article, no thorough search vd Aalst: pattern-based comparison: –WSCI – BPML offer same functionality too much overlap to justify separation WSCI can be used to model –BPEL4WS – BPML little more expressive no semantics too many overlapping constructs

13 Eyal Oren13 Useful for WSMO either: borrow requirements –asynchronicity –exception management –compensation –message correlation –control flow construct (workflow patterns, vd Aalst) or: use a standard

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