What Is a Web Service?

A web service is any piece of software that uses REST and/or a standardized XML messaging system, described by a WSDL (Web Service Definition Language) (pronounced "wiz-dal"), to exchange data between applications or systems. A web service must have some simple mechanism for interested parties to locate the service and its public interface using standard network protocols, such as, but not limited to, SOAP over HTTP. Software applications written in various programming languages and running on various platforms can use web services transparently to exchange data over computer networks, like the Internet, because the WSDL serves as the definition of the language used by the computers.

In Product Advertising API::

  1. Requests and responses occur across the Internet.
  2. Client and server use REST, SOAP, or XML as the means of communication.
  3. Client and server agree on the grammar and syntax used in the requests and responses by specifying a WSDL.
  4. XML Response message format received as SOPA response message.
  5. Requests and responses are not tied to a single operating system or programming language.

A simple example of a Product Advertising API request uses the ItemSearch operation.

  1. You submit a request with the ItemSearch operation. The operation asks web servers to find descriptions of an item in its databases..
  2. The web servers carry out their service by finding the item descriptions.
  3. The web servers send the item data back to the requester.

All Product Advertising API requests are based on REST or SOAP and all of the responses are based on XML.