IV.5.1. Using Web Services to Distribute Data

A Web service is a software system used to transfer data across a network. That network could be the Internet, an intranet, or even an extranet. A Web service is designed to accept requests for information and return information based on the request.

The requests can be very simple or complex. Some common data returned by Web services include

  • Weather data: A ZIP code is passed into the service, and weather information (such as current temperature and future predictions) is passed back.

  • Order status: An order ID is passed into the service, and the current status of the order (such as shipped or being processed) is passed back.

  • Shipping status: A tracking number is passed into the service, and the current location or other shipping information is passed back.

Web services have several key elements:

  • Provider: The Web services provider gives the data that's requested from the Web services requestor. This could be a compiled application, or it could simply be SQL Server.

  • Requestor: The requestor queries the provider for specific information. The requestor is often a Web application that's used to embed information into a Web page.

  • Web Services Description Language (WSDL): WSDL (pronounced Wizzdull) can be thought of as a contract. It identifies specifically what can be requested and what will be returned. For example, a WSDL for a Web service designed to provide order statuses would specify how a valid order ID could be provided and then identify ...

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