1. 1 Understanding Web Services Presented By: Woodas Lai

2. 2 Understanding Web Services By Jaideep Roy and Anupama Ramanujan What is Web Services? Architecture Core technologies XML SOAP WSDL UDDI

3. 3 What is Web Services?  A Web Services is a unit of application logic providing data and services to other applications  They are published to the Web in such a way that other applications can find and use them

4. 4 Examples of Web Services a credit card service that processes credit card transactions for a given account a market data service that provides stock market data associated with a specified stock symbol

5. 5 Architecture

6. 6 Core Technologies Technologies for Web Services XML UDDI ( XML Based ) SOAP ( XML Based ) WSDL ( XML Based )

7. 7 SOAP Simple Object Access Protocol (SOAP) http://www.w3.org/TR/SOAP/ A lightweight XML communication message protocol

8. 8 Role of SOAP

9. 9 SOAP Overview Describe the messaging format for machine-to-machine communication Enable procedure calls on remote objects Define elements to specify remote function names, parameters and return types

10. 10 SOAP Overview Support different Internet protocols, such as HTTP, SMTP, FTP (Protocol neutral) SOAP = XML + RPC + HTTP (Typical use) A SOAP document is an XML document designed to invoke methods on remote computers over HTTP

11. 11 SOAP Structure

12. 12 SOAP Example …… http://www.w3.org/2001/06/soap- encoding DIS

13. 13 WSDL Web Services Description Language (WSDL) http://www.w3.org/TR/wsdl Description of Web Services via XML-based standard format Define the set of functions supported by the server and the formats a client should be used to request the service, like IDL in CORBA

14. 14 WSDL WSDL is used to describe the web services. So, how to describe? WSDL has its own XML vocabulary defined so as to describe the web service

15. 15 WSDL has a well-defined XML vocabulary to answer the following questions regarding the web service involved: What does the service do? Both in machine and human-readable forms What language does the service speak? The format/data structure of the message exchanged WSDL

16. 16 How does the client talk to the service? HTTP/SMTP/FTP Where is the location of the web service? The access point (URL) WSDL

17. 17 WSDL <wsdl:definitions targetNamespace="http://137.189.94.136:8080/axis/echo.jws" xmlns="http://schemas.xmlsoap.org/wsdl/" xmlns:apachesoap="http://xml.apache.org/xml-soap" xmlns:impl="http://137.189.94.136:8080/axis/echo.jws" xmlns:intf="http://137.189.94.136:8080/axis/echo.jws" xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/" xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:wsdlsoap="http://schemas.xmlsoap.org/wsdl/soap/" xmlns:xsd="http://www.w3.org/2001/XMLSchema">

18. 18 WSDL <wsdl:input message="intf:echoStringRequest" name="echoStringRequest" /> <wsdlsoap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http" /> <wsdlsoap:body encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" namespace="http://137.189.94.136:8080/axis/echo.jws" use="encoded" />

19. 19 WSDL <wsdlsoap:body encodingStyle=http://schemas.xmlsoap.org/soap/encoding/http://schemas.xmlsoap.org/soap/encoding/ namespace=http://137.189.94.136:8080/axis/echo.jwshttp://137.189.94.136:8080/axis/echo.jws use="encoded" />

20. 20 UDDI Universal Description, Discovery, and Integration Specifications for service description and discovery Open-Standard Raised By Ariba, IBM and Microsoft http://www.uddi.org (by Oasis) http://www.uddi.org XML-based message

21. 21 Service Architecture UDDI defines a way to publish and discover information about Web services

22. 22 UDDI Information about the business (company name, company address ……) Categorization of the business and its services Technical information about services provided by a business (like the URL to invoke the Web Services) White Page Yellow Page Green Page

23. 23 Core Structures of UDDI Business Entity White Pages information Business Services Yellow Pages information Binding Templates Green Pages information Contains references to tModels tModels Service Type Definitions Interface specifications for a service (WSDL)

24. 24 Research Challenge How to secure the Web Services Invocation? How to ensure the reliability of the Web Services? How to deal with the Quality of Services?

25. 25 Q&A