webservicearchitecture-150614164814-lva1-app6892.ppt
- 2. Table of Contents • What’s Web Service? • Web Service Model • Architecture Overview – SOAP – WSDL – UDDI • Conclusion
- 3. What’s Web Service? • “Software application identified by a URI, whose interfaces and bindings are capable of being defined, described, and discovered as XML artifacts” – W3C Web Services Architecture Requirements, Oct. 2002 • “Programmable application logic accessible using Standard Internet Protocols…” – Microsoft • “An interface that describes a collection of operations that are network accessible through standardized XML messaging …” – IBM • “Software components that can be spontaneously discovered, combined, and recombined to provide a solution to the user’s problem/request … “ - SUN
- 4. Web Services: The Next Horizon for e- business • Allow companies to reduce the cost of doing e-business, to deploy solutions faster – Need a common program-to-program communications model • Allow heterogeneous applications to be integrated more rapidly, easily and less expensively • Facilitate deploying and providing access to business functions over the Web
- 5. Sun J2EE MS .NET Platform CORBA
- 6. Table of Contents • What’s Web Service? • Web Service Model • Architecture Overview – SOAP – WSDL – UDDI • Conclusion
- 7. Web Service Model (1/3)
- 8. Web Service Model (2/3) • Roles in Web Service architecture – Service provider • Owner of the service • Platform that hosts access to the service – Service requestor • Business that requires certain functions to be satisfied • Application looking for and invoking an interaction with a service – Service registry • Searchable registry of service descriptions where service providers publish their service descriptions
- 9. Web Service Model (3/3) • Operations in a Web Service Architecture – Publish • Service descriptions need to be published in order for service requestor to find them – Find • Service requestor retrieves a service description directly or queries the service registry for the service required – Bind • Service requestor invokes or initiates an interaction with the service at runtime
- 10. Table of Contents • What’s Web Service? • Web Service Model • Architecture Overview – SOAP – WSDL – UDDI • Conclusion
- 12. SOAP: Simple Object Access Protocol • What is SOAP? – SOAP is a communication protocol – SOAP is for communication between applications – SOAP is a format for sending messages – SOAP is designed to communicate via Internet – SOAP is platform independent – SOAP is language independent – SOAP is based on XML – SOAP is simple and extensible – SOAP will be developed as a W3C standard
- 13. SOAP: Simple Object Access Protocol • SOAP 1.0: Microsoft, Userland, DevelopMentor – Specific to COM and HTTP • SOAP 1.1: includes contributions from IBM and Lotus – Substitutable transport binding (not just HTTP) – Substitutable language binding (e.g. Java) – Substitutable data encoding – Completely vendor-neutral – Independent of: programming language, object model, operating system, or platform • SOAP 1.2: current working draft from w3.org “XML Protocol” working group
- 14. SOAP Message Structure • Request and Response messages – Request invokes a method on a remote object – Response returns result of running the method • SOAP specification defines an “envelop” – “envelop” wraps the message itself – Message is a different vocabulary – Namespace prefix is used to distinguish the two parts Application-specific message vocabulary SOAP Envelop vocabulary
- 15. SOAP Request Message <?xml version="1.0"?> <soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope" soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding"> <soap:Body xmlns:m="http://www.stock.org/stock"> </soap:Body> </soap:Envelope> <m:GetStockPrice> <m:StockName>IBM</m:StockName> </m:GetStockPrice> SOAP Envelope Message SOAP Envelope Namespace Message Namespace
- 16. SOAP Response Message <?xml version="1.0"?> <soap:Envelope xmlns:soap="http://www.w3.org/2001/12/soap-envelope" soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding"> <soap:Body xmlns:m="http://www.stock.org/stock"> </soap:Body> </soap:Envelope> <m:GetStockPriceResponse> <m:Price>34.5</m:Price> </m:GetStockPriceResponse> SOAP Envelope Message Result returned in Body
- 17. • SOAP hides the technical choices and implementation details from both parties Simple standard XML Message
- 18. Why SOAP? • Other distributed technologies failed on the Internet – Unix RPC – requires binary-compatible Unix implementations at each endpoint – CORBA – requires compatible ORBs – RMI – requires Java at each endpoint – DCOM – requires Windows at each endpoint • SOAP is the platform-neutral choice – Simply an XML wire format – Places no restrictions on the endpoint implementation technology choices
- 19. SOAP Usage Models • RPC-like message exchange – Request message bundles up method name and parameters – Response message contains method return values – However, it isn’t required by SOAP • SOAP specification allows any kind of body content – Can be XML documents of any type – Example: • Send a purchase order document to the inbox of B2B partner • Expect to receive shipping and exceptions report as response
- 20. Web Services Description Language • What is WSDL? – WSDL is written in XML – WSDL is an XML document – WSDL is used to describe Web services – WSDL is also used to locate Web services – WSDL is not yet a W3C standard • Operational information about the service – Location of the service – Service interface – Implementation details for the service interface
- 21. WSDL Document Structure (1/2) • <portType> element – Defines a web service, the operations that can be performed, and the messages that are involved • <message> element – Defines the data elements of an operation – consists of one or more parts. – The parts can be compared to the parameters of a function call in a traditional programming language
- 22. WSDL Document Structure (2/2) • <types> element – Defines the data type that are used by the web service – For maximum platform neutrality, WSDL uses XML Schema syntax to define data types • <binding> element – Defines the message format and communication protocols used by the web service
- 23. <message name="getTermRequest"> <part name="term" type="xs:string"/> </message> <message name="getTermResponse"> <part name="value" type="xs:string"/> </message> <portType name="glossaryTerms"> <operation name="getTerm"> <input message="getTermRequest"/> <output message="getTermResponse"/> </operation> </portType> WSDL Example
- 24. <message name="getTermRequest"> <part name="term" type="xs:string"/> </message> <message name="getTermResponse"> <part name="value" type="xs:string"/> </message> <portType name="glossaryTerms"> <operation name="getTerm"> <input message="getTermRequest"/> <output message="getTermResponse"/> </operation> </portType> <binding type="glossaryTerms" name="b1"> <soap:binding style="document" transport="http://schemas.xmlsoap.org/soap/http" /> <operation> <soap:operation soapAction="http://example.com/getTerm"/> <input> <soap:body use="literal"/> </input> <output> <soap:body use="literal"/> </output> </operation> </binding> Binding to SOAP
- 25. Universal Description, Discovery and Integration (UDDI) • What is UDDI? – Directory service where businesses can register and search for Web services • Directory for storing information about web services • Directory of web service interfaces described by WSDL – UDDI communicates via SOAP • What is UDDI Based On? – Uses W3C Internet standards such as XML, HTTP, and DNS protocols – UDDI uses WSDL to describe interfaces to web services
- 26. UDDI Roles and Operations • Service Registry – Provides support for publishing and locating services – Like telephone yellow pages • Service Provider – Provides e-business services – Publishes these services through a registry • Service requestor – Finds required services via the Service Broker – Binds to services via Service Provider
- 27. How can UDDI be Used?
- 28. UDDI Benefits • Making it possible to discover the right business from the millions currently online • Defining how to enable commerce once the preferred business is discovered • Reaching new customers and increasing access to current customers • Expanding offerings and extending market reach
- 29. Types of UDDI nodes (1/3) • Internal Enterprise Application UDDI node – Web Services for use within a company for internal enterprise application integration – The scope can be single application, departmental, corporate – Sit behind the firewall – Allow the service providers more control over their service registry and its accessibility
- 30. Types of UDDI nodes (2/3) • Portal UDDI node – Web Services published by a company for external partners to find and use – Runs outside the service provider’s firewall – Contains only those service descriptions that a company wishes to provide to service requestors from external partners • Partner catalog UDDI node – Web services to be used by a particular company – Runs behind the firewall – Contains only approved, tested and valid Web service descriptions for legitimate business partners
- 31. Types of UDDI nodes (3/3) • E-Marketplace UDDI node – Web Services that the service provider intends to compete for requestors’ business with other Web Services – Hosted by an industry standards organization or consortium – Contains service descriptions from businesses in a particular industry
- 33. Conclusion • Web Serivices substitute for existing distributed computing model such as RPC, CORBA • To apply to real e-business application, the following problems should be covered – Security – Transaction Management – QOS (ex., reliable message transmission) – Efficient methods for composing Web Services