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Web Services 101 Introduction to Web Services

Web Services 101 Introduction to Web Services. 2110472 Computer Networks Natawut Nupairoj, Ph.D. Department of Computer Engineering Chulalongkorn University. Outline. What is web service ? Any why ? Service-Oriented Architecture. Web Services Products. Existed and Future Applications.

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Web Services 101 Introduction to Web Services

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  1. Web Services 101Introduction to Web Services 2110472 Computer Networks Natawut Nupairoj, Ph.D. Department of Computer Engineering Chulalongkorn University

  2. Outline • What is web service ? Any why ? • Service-Oriented Architecture. • Web Services Products. • Existed and Future Applications. • Trends and Future.

  3. What is web service ? “Next-generation service-oriented Internet applications.” “Component-based software architecture.” “A concept of a programmable Internet.”

  4. OK, what really is web service ? • Well…nobody really knows for sure. • Everyone has its own definition. • Something in common • Software components with well-defined interfaces. • Communicating through XML-based messaging. • Connecting via HTTP-based protocol.

  5. Why then ? • Everybody is doing it !!!

  6. No…that’s not a good answer!!!

  7. Web Services Model

  8. Driving Forces • E-business trends • Flexible architecture. • From RPC to messaging-centric model. • Business needs • EAI – Enterprise Application Integration. • B2B / G2G.

  9. The Ultimate Goals • Web service is • Platform independent. • Implementation independent. • Software Components. • Features • Described using a service description language. • Published to a registry of services. • Discovered through a standard mechanism. • Invoked through a declared API over a network. • Composed with other services.

  10. Service Oriented Architecture • Publish – Find – Bind. Service Registry WSDL UDDI Find Publish SOAP Service Requestor Service Provider Bind

  11. Web Services Interoperability Stacks • Proposed to W3C by IBM and Microsoft in March 2001 • Wire stack. • Description stack. • Discovery stack.

  12. Wire Stack • Determine how a message is sent from the service requestor to the service provider. • Components • HTTP (SMTP, FTP, RMI/IIOP, MQSeries). • XML. • SOAP. “XML-based RPC over HTTP”

  13. SOAP RPC Request POST /bws/inventory.jws HTTP/1.0 … <?xml version=“1.0” encoding=“UTF-8”?> <SOAP-ENV:Envelope SOAP-ENV:encodingStyle=http://schemas.xmlsoap.org/soap/encoding/ xmlns:xsd=http://www.w3.org/2001/XMLSchema xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/ xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance> <SOAP-ENV:Body> <doCheck> <arg0 xsi:type=“xsd:string”>947-TI</arg0> <arg1 xsi:type=“xsd:int”>1</arg1> </doCheck> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

  14. SOAP RPC Response HTTP/1.0 200 OK … <?xml version=“1.0” encoding=“UTF-8”?> <SOAP-ENV:Envelope SOAP-ENV:encodingStyle=http://schemas.xmlsoap.org/soap/encoding/ xmlns:xsd=http://www.w3.org/2001/XMLSchema xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/ xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance> <SOAP-ENV:Body> <doCheckResponse> <doCheckResult xsi:type=“xsd:boolean”>true</doCheckResult> </doCheckResponse> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

  15. SOAP Messaging <?xml version=“1.0” encoding=“UTF-8”?> <SOAP-ENV:Envelope SOAP-ENV:encodingStyle=http://schemas.xmlsoap.org/soap/encoding/ xmlns:xsd=http://www.w3.org/2001/XMLSchema xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/ xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance> <SOAP-ENV:Body> <po xmlns=http://www.skatestown.com/ns/po id=“503383” submitted=“2001-12-06”> <billTo> <company>The Skateboard Warehouse</company> <street>One Warehouse Park</street> … </billTo> … </po> </SOAP-ENV:Body> </SOAP-ENV:Envelope>

  16. Description Stack • Describe the details of the service • What a service does (provided methods). • How a service is accessed (data format & protocol). • Where a service is located (e.g. URL). • WSDL / WSEL • XML-based format. • Service implementation and interface. • Endpoint description.UDDI.

  17. Discovery Stack • Provide service discovery mechanism. • There are 2 levels • Inspection – discovering the service description given that service identifier (URL) is known. • IBM’s ADS and Microsoft’s DISCO. • Directory – capabilities-based lookup. • UDDI.

  18. What are in the market ? • J2EE • BEA – WebLogic Server. • IBM – WebSphere SOAP toolkit. • Sun – SunOne. • Iona – XMLBus • Macromadia – JRun 3.1 / JRun 4.0. • Apache – Axis (SOAP API). • University of Indiana – SOAP-RMI. • Mind Electric – GLUE. • Microsoft’s .NET

  19. Any existing applications ? • Yes…there are some… • Dealersphere • National Auto Dealer Association. • Car dealers to communicate with other companies via ebXML and SOAP. • Features? • Handling credit checks. • Getting the exact color and car options. • Locating the car at another dealer.

  20. Any existing applications ? • Public eService Infrastructure (PSi) • iDA Singapore. • Integrate over 600 online services from several government agencies. • Ex: • Request for a new driver’s license. • Service provided by Land Transport Authority of Singapore. • However, citizen information is needed from Citizen Department. • And payment must be made online. • Other services also need these information.

  21. Future applications ? • Authentication services • Microsoft’s Passport. • Liberty Alliance. • Agent-based shopping. • Internet syndication.

  22. Conclusion • Web services is still unclear • Open areas. • Or just a hype! • Publish + find + bind = WSDL + UDDI + Soap

  23. References • S. Graham et. al, “Building Web Services with Java”, SAMS Publishing, 2002. • http://www.webservices.org • And others…

  24. Questions ?

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