Python & XML

Sample Application and Flow Analysis

We will create a large sample application to illustrate many different concepts and show how they can be used together. An intelligent XML switch that knows how to move XML in the right direction holds the distributed application together. We also discuss how these switches can be daisy-chained together to form scalable networks of XML data. The components that are connected to the switch include a user input application, a customer profile SQL database, and an XML information store. Figure 10-1 shows a diagram of the application.

Figure 10-1. The sample distributed application

This application is meant to illustrate how several different applications that may have different purposes can utilize the same flow of XML traffic in the network by building intelligence between them, and not retrofitting them. The key to this application’s success is in the way the XML is moved between the applications in a decoupled fashion. From a high-level, the application appears as a portal web site to end-users. Backend systems of different types are integrated by exposing XML messaging APIs, allowing the portal to work. Other applications connect along the peripheral boundary of the main processing, to participate in the flow of XML information.

Decoupling Application Systems

Take for instance the Web/CGI application on the righthand side of Figure 10-1. Typically, ...