Web and Binary-Exchange Services

This book also classifies services by the format of the data exchanged between a service and its requesters. A Web service exchanges data in a format based on Extensible Markup Language (XML). The W3C Web site suggests that the use of XML for data transfer is the only defining characteristic of a Web service. In many cases, the following description also applies:

• Details on the data are described in Web Services Description Language (WSDL).

• The format of the transmitted data is Simple Object Access Protocol (SOAP).

• The transport protocol is Hypertext Transfer Protocol (HTTP), the primary mechanism for exchanging program data over the Internet or a corporate intranet.

In contrast to a Web service, a binary-exchange service exchanges data in a format associated with a particular computer language or a specific vendor. Although a service written with Enterprise Generation Language (EGL) can be deployed as a Web service, for example, the logic also can be deployed as a service that exchanges binary data.

The use of binary-exchange services provides several benefits:

• allows a faster runtime response than is possible with Web services

• avoids the need to maintain WSDL definitions and related files

• avoids the need to learn the Web-service technologies

The cost, however, is reduced accessibility. A binary-exchange service is directly accessible only to software that transmits data in the binary format expected by the service.