BULLETINS

Web service is a web application that can be accessed over internet through web API. API is used for application to application communication. Web services uses XML and standard web protocols to communicate through internet.
Web services use numerous different protocols for the exchange of data. One of the protocols is SOAP (Simple object accessible protocol). HTTP (Hyper Text Transfer Protocol) is the most popular option for service transport. Most firewalls allow HTTP traffic. When all major platforms can access the Web using Web browsers, different platforms can interact. Any web service hosted on windows can also be consumed by UNIX and Linux platform. For these platforms to work together, Web-applications were developed. Web-applications are simple applications that run on the web. These are built around the Web browser standards and can be used by any browser on any platform.
Consumers of a Web Service need not know anything about the platform, object model, or programming language used to implement the service; they only need to understand how to send and receive SOAP messages (HTTP and XML).

Features:

• Platform independent (They can be deployed in any platform).
• Language independent (They can be consumed using any technology).
• Interoperable.
• Reusable application components.
• Rapid development

Web services platform elements:

• SOAP (Simple Object Access Protocol)
• UDDI (Universal Description, Discovery and Integration)
• WSDL (Web Services Description Language)
• DISCO

SOAP (Simple Object Access Protocol)

SOAP is an XML based communication protocol to exchange data between computers. SOAP is platform independent so that it can go around firewalls.

WSDL (Web Services Description Language)

WSDL exposes the structure of the Web Service. It is used to locate a web service which is based on XML and describes how to access them. WSDL also describes the methods and properties that the service supports, the data type it supports and the supported protocols.

UDDI (Universal Description, Discovery and Integration)

UDDI is a directory where web services can be registered and find existing web services. It acts as a public registry where we can publish and search Web service. It uses WSDL to describe interfaces to web services.

DISCO stands for Discovery.

It basically groups common services together on a server and provides the links to the schema documents of the services that it describes.
Hope you have a basic idea about Web services now.