2. An Introduction to Web Services

3. Web Services using Java / Session 1 / 2 of 21 Objectives Discuss distributed computing Explain web services and their characteristics Discuss the generic architecture of web services Describe the life cycle of a web service Identify the requirements for a web service Explain the working of a web service Discuss the advantages and disadvantages of web services

4. Web Services using Java / Session 1 / 3 of 21 Component Architecture Components Method 1…… User submits parameters Appropriate Method called Returns the result Application Method 2……

5. Web Services using Java / Session 1 / 4 of 21 Application Computing Over the Years (1) Database Stand-alone Computers

6. Web Services using Java / Session 1 / 5 of 21 Client-Server Computing Server Clients: Smart terminals PC Computing Over the Years (2)

7. Web Services using Java / Session 1 / 6 of 21 Distributed Computing Smart terminals Network Distributed Computing Component A Windows OS Component B Component F Linux OS Component CComponent D Component E

8. Distributed Component Architectures  The three main Distributed Component Architectures are: CORBA Developed by OMG DCOM Developed by Microsoft RMI Developed by SUN. Uses CORBA for Heavy-Duty Distributed Systems

9. Web Services using Java / Session 1 / 8 of 21 Inter-Module Communication Application developed using C# Application developed using VB.net Inter-Module communication needs: 1. Set of rules for communication 2. Standard Language for interfaces 3. Interfaces for the modules

10. Web Services using Java / Session 1 / 9 of 21 Web-based Applications Must be simple, self explanatory and easy to use Services Offered e-mail, browsing, searching the net, chat applications Devices Used to Access the Web

11. Web Services using Java / Session 1 / 10 of 21 Web Services Network Network may be LAN, WAN, MAN or Internet  Web Services: Internet based modular applications Web Service

12. Web Services using Java / Session 1 / 11 of 21 Web Services Solutions Two of the most popular Web Services Solutions SUN TM OPEN NET ENVIRONMENT (SUN ONE)

13. Web Services using Java / Session 1 / 12 of 21 Web Service Example EMI Calculator Web Service Loan Application Using Web Service Running on Another Web Service

14. Web Services using Java / Session 1 / 13 of 21 Characteristics of Web Services Should be registered Uses XML Uses standard web protocols Accessed over the web Web Services Has a service interface Supported by loosely coupled applications Integrated Just In Time

15. Web Services using Java / Session 1 / 14 of 21 Important Components Service Broker Service Requestor Service Provider Service Registry Publish Find Bind

16. Web Services using Java / Session 1 / 15 of 21 Web Services: Generic Architecture

17. Web Services using Java / Session 1 / 16 of 21 Life Cycle 1. Create a web service 2. Define service interface, invocation methods for the web service 3. Publish the web service on the Internet or Intranet 5. Invoke the web service 6. Unpublish the web service when not needed 4. Search for the web service

18. Web Services using Java / Session 1 / 17 of 21 Requirements for a Web Service XML: Represent data in a standard format SOAP: Common extensible message format WSDL: Common, extensible, service description language UDDI: Maintains registries storing information about service providers and their services

19. Web Services using Java / Session 1 / 18 of 21 Working of a Web Service Soap Protocol XML over HTTP Parameters Return Value Get Type info (XML Schema) Service Description Web Server (With Web Service) Client Application

20. Web Services using Java / Session 1 / 19 of 21 Accessing Web Services over HTTP HTTP GET operation HTTP POST operation SOAP

21. Web Services using Java / Session 1 / 20 of 21 Business Process Web Service Organization A Organization B Advantages of Web Services  Cross business integration  Improved efficiency  Closer customer relationships  Facilitates just-in-time integration  Reduces complexity  Legacy applications

22. Web Services using Java / Session 1 / 21 of 21 Constraints Businesses not willing to expose the functionalities The only technology that forms the base is XML, that means we cannot do without XML The cost involved is very high