What is the use of a .disco file?

A client application uses a .disco file to locate or discover the documents that contain the description of a Web service. The .disco file contains links to other resources, which describe essential features, such as capabilities of a Web service. The links contained in a .disco file can refer to other discovery documents or XSD schemas. The description about the services and capabilities of a Web service is written in Web services Description Language (WSDL). A .disco file can also contain the information about other XML Web services that reside on the same or a different Web server.

What are the names of public properties defined in the WebService class.

There are many properties defined in the WebServices class:

• Application - Obtains the application object for the current HTTP request
• Context - Obtains the HttpContext object for the current request, which encapsulates all HTTP-specific context used by the HTTP server to process Web requests
• Server - Obtains the HttpServerUtility object for the current request
• Session - Obtains the HttpSessionState object for the current request
• SoapVersion - Obtains the version of the SOAP protocol used to make the SOAP request to a Web service
• User - Obtains the Server User Object. This property can be used to authenticate whether a user is authorized to execute the request.

Explain the concept of Web services in brief.

A Web service may be defined as an independent and self-sustained unit of a software application that is hosted on the Web and implement specific functionalities to execute the business logic. A Web service provides so many functionalities, such as generating pay slips for employees, computing tax, broadcasting weather report, and providing updated news. The Web service allows applications to share information or exchange data with other applications across different operating systems and hardware.

Therefore, the work of a Web service is to unite software by exchanging data irrespective of their operating systems, supported hardware, and programming language used in their development. The Web services transfer data in the XML format and use Simple Object Access Protocol (SOAP) to communicate. It is an XML-based protocol. The Web services use Web Services Description Language (WSDL) and Universal Description, Discovery, and Integration (UDDI) to describe itself.

Explain the WSDL.

WSDL is a short form for Web Services Description Language, which is used to describe a Web service in terms of the messages that it creates and accepts. The WSDL document is an XML file that contains the interface schema for the Web service. It identifies the methods that are used during the exchange between a Web service consumer and a Web service provider. The following are the elements contained in the WSDL document:

• Types - Describe the variations of data types that are used to exchange messages between the user and the provider.
• Message - Describes the actual message or method call.
• portType - Describes the set of operations and each related message.
• binding - Describes the protocol details.
• service - Used to make groups a set of related ports together.