Web Service ImplementationUsing ASP.NET T.Ponraj , Research Assistant, Pondicherry University, Puducherry.
Web services Definition: Software components that can be published, located, and run over the Internet using Extensible Markup Language (XML). A web service is a software application that works over the internet. A web service is service-oriented application that communicates over the web using messages We can test the web service by using the local web server.
Working of web service The web service is also a software, with its own class and methods . A request by the client application constitutes construction and sending a SOAP request using HTTP to the web server. For a web service to work, the computer has to be connected to the internet. The web server hosts the class and its methods of a web service, for a client computer to request and use. Any client computer located any where in the world, with an internet connection can request and use the class and its methods of the web service.
Web Service technologies A web service is service-orientedapplication that communicates over the webusing messages. The Web XML SOA
1 . The Web A Web service is a Web resource. It communicates over the internet using standard Web protocols. Leveraging the Web yields universal connectivity and pervasiveness. A web service is also hosted on a web server. We can access a web service programmatically, only programmatically and not by a browser.
2 . XML XML is a language for electronic documents and messages. It provides a universal, self-describing data format that can be interpreted, processed, and transformed by any application running on any platform. Each bit of information in a document is defined by tags without overload of formatting present in HTML. This type of representation is suitable for application to application communication.
3 . SOA SOA stands for service-oriented architecture. SOA is a concept and describes a set of well- established patterns. Each pattern represents a mechanism to describe a service, to advertise and discover a service, and to communicate with a service. Web services rely on these patterns and client applications connect to a service using these patterns.
3.1.Basic Roles Service provider :- Who develops or supplies the service. Service consumer :- Who uses the service. Service broker :- Facilitates the advertising and discovery process.
3.2.Operation Register :- The service provider registers the service with a service broker. Find :- The service broker gives the service consumer directions on how to find the service and its service contract . Bind :- The service consumer uses the contract to bind the client to the service, at which point the client and service can communicate.
3.3 . Standard WSDL :- WSDL provides a mechanism to describe a Web service. UDDI :- UDDI provides a mechanism to advertise and discover a Web service. SOAP:- SOAP provides a mechanism for clients and services to communicate.
3.3.3.SOAP Simple Object Access Protocol (SOAP) is an XML protocol. It is used by client applications to communicate with Web services. SOAP implements an envelope for sending an XML message. We put an XML message into an envelope and send it across the networks. A SOAP envelope is transported by various communication protocols. But, the most common way to transfer SOAP messages is to use HTTP. Other Web protocols commonly used are SMTP and FTP.
SOAP Message A SOAP message consists of two parts. SOAP header :- It includes system level information. SOAP body :- It contains the message the information that is being sent.
Reason for why we use Web Services Web Services operate on a service-based model architecture . Web Services allow us to communicate among all different entities without affecting their existence. It is written separately from the application logic. They improve the information flow between applications. web services use text based protocol that all applications can understand. Web services reduce licensing costs. They do not rely on special protocols.