Application Integration with Web Services

Web services enable companies to integrate applications over networks using standard Internet protocols. This illustration shows a scenario in which a newly acquired subsidiary (left) wants to integrate its accounting application with an application at corporate headquarters (right). Each organization creates a Web service that acts as a front end to its application. The organizations also agree on an XML message format for the data their applications need to exchange (e.g., sales data, product catalogs), based on the Simple Object Access Protocol (SOAP).

A typical transaction proceeds as follows: The subsidiary’s Web service extracts sales data from the subsidiary’s accounting system via an application-specific API. It packages the sales data into a SOAP message and sends the message to the Web service at headquarters using the Web-standard Hypertext Transfer Protocol (HTTP) The Web service at headquarters extracts the sales data from the message and posts the data to its own application. It then packages the application’s response into a SOAP reply message and sends that message back to the subsidiary’s Web service.