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Web Services and Seamless Interoperability

Web Services and Seamless Interoperability. João Paulo Almeida ( almeida@cs.utwente.nl ) Luís Ferreira Pires ( pires@cs.utwente.nl ) Marten van Sinderen ( sinderen@cs.utwente.nl ) Centre for Telematics and Information Technology (CTIT), University of Twente. Web Services are about….

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Web Services and Seamless Interoperability

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  1. Web Services and Seamless Interoperability João Paulo Almeida (almeida@cs.utwente.nl) Luís Ferreira Pires (pires@cs.utwente.nl) Marten van Sinderen (sinderen@cs.utwente.nl) Centre for Telematics and Information Technology (CTIT), University of Twente

  2. Web Services are about… • SOAP, WSDL, XML Schema, UDDI, BPEL4WS, …

  3. Web Services are about… and about… • SOAP, WSDL, XML Schema, UDDI, BPEL4WS, … • Web Services hosting platforms • JAX-RPC / JSP / EJB / Java • .NET / CLR / XML Web Services / C# • CORBA / C++, Java, COBOL, … • CCM • Add your favourite: • middleware platforms • programming languages

  4. There are always other platforms involved

  5. Mismatch: Web Services x Hosting Platform • Mappings: • from and to Java in the JAX-RPC specification • from and to .NET’s Common Type System • from and to CORBA IDL • recurring: and then to programming languages • Can be automated, and spare us from a lot of work • (WSDL may be “human readable” (?) but I prefer Java)

  6. Mismatch: Web Services x Hosting Platform • Mismatch Example: • A Java developer is used to passing remote object references as parameters in J2EE • Not if an object is to be exposed as a web service endpoint (JAX-RPC) • Lots of patterns used will depend on references

  7. Mismatch: Web Services x Hosting Platform • Divergences in the behavior of components of different technology domains • E.g., use of the Naming Service in CORBA • Even if the mapping from SOAP/IIOP were transparent, requesters would have to be able to use the Naming Service • Rule of thumb: • Avoid exposing such “internal”characteristics in a web services definition • Works with trivial web services • Assumes services can be simplified regardless of complexity of service requester - service provider interactions

  8. Challenge: Seamless interoperation • Developers should be shielded from: • the existence of different middleware platforms and programming languages • and from the resulting mismatch • We need support to accommodate the differences, to: • provide abstractions that are suitable and intuitive for application developers, and • re-use specifications and components defined in terms of the abstractions of particular technology domains

  9. Opportunity: MDA and platform-independence

  10. Risk: it starts again...

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