A web service represents a communication interface offered by the server, through that the clients (programs on other systems) may require different information. The customer may vary, may be present on the same computer server, may be in the same local network or it may be located in the opposite part of the country. It is a method by which applications can communicate with each other through asynchronous messages or calls on remote procedure (RPC Remote Procedure Call). So it can be concluded that a Web service is a software application that can be accessed remotely using XML-based languages. Web services are just two programs that change data between them on the Internet or Intranet in XML format called SOAP (Simple Object Access Protocol).