Web service has three main components:

i) SOAP
ii) WSDL and
iii) UDDI

i) SOAP

Simple Object Access Protocol (SOAP) is a communication protocol that communicates between applications without understanding the configuration and programming of any operating system and programming language. A program from one computer system can communicate with other program on another computer system within and beyond network using SOAP protocol on the Internet.

SOAP can run on any operating system and need not to assess the programming code. It is based on XML and HTTP and runs using the nexus of both on to the Internet. SOAP is simple and extensible and allows the user to woo firewall. It is a mechanism generally used for information exchange over the Internet.

Since the emerging of web protocols that runs on all major operating system platforms, HTTP and XML solve the problem of running within different operating systems and in different programming language. Similar like this, SOAP also describes how to encode an HTTP header and an XML file to make communication between two computers and call any program from one’s to others. SOAP will also describe the criteria of returning the response of the program.

Microsoft, DevelopMentor, and Userland Software have jointly developed the SOAP and promoted it as a standard interface to the Internet Engineering Task Force (IETF). It is a little bit analogous to the Internet Inter-ORB Protocol (IIOP). IIOP is a protocol that is a part of the Common Object Request Broker Architecture (CORBA). The program calls through SOAP protocol has a benefit of that it can interact firewall servers, which screen out the request other than those for known applications using designated port mechanism.

ii) WSDL

Web Services Description Language (WSDL) is an XML-based language written in XML and used for describing Web services and the process of accessing it. It is also used for locating web services. WSDL specify the network services, location service and operation services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. The operations and messages are illustrated conceptually, and then leap to a concrete network protocol and message configure to identify an endpoint. The integrated concrete endpoints are tied up with abstract endpoints (services). The WSDL navigates for individuals and other business to access the service

The Web Services Description Language (WSDL) is an XML-based language used to describe the services a business offers and to provide a way for individuals and other businesses to access those services by electronic means. WSDL is the base of the Universal Description, Discovery, and Integration (UDDI) that facilitate businesses to be listed themselves and their services on the Internet.