Stages in the Application Development Process

A fully functional notification application is likely to be a sophisticated piece of software, consisting of several modules with complex interactions and dependencies. At the start, it can be difficult to correctly predict the implementation details of an application in its entirety. For this reason, SQL-NS applications are usually developed in stages. Figure 5.2 shows the various stages in the process.

Figure 5.2. The development process for a SQL-NS application.

Development begins with a high-level initial design. This design specifies the important characteristics of the application and scopes the problem that the application will solve. The section "Initial Design: Seven Important Questions About Your Application" (p. 124) describes the questions about your application that need to be asked and answered at the design stage.

After the initial design is complete, you then move on to building a prototype. The prototype essentially consists of the application's matching component, shown at the center of Figure 5.1. However, instead of connecting the matching component to the real input and output components that the application will ultimately work with, you use the test facilities that SQL-NS provides to feed sample data into the matching component and observe the output it generates. Using these facilities, you can determine whether the application's matching logic is working correctly, without concerning yourself with the details of the real input and output components.

As you build the prototype, you'll test it, debug problems, and make refinements as necessary. You may go through several iterations before the prototype is complete. In this chapter, we'll begin prototyping the music store application. In the "Building the Application Prototype" section (p. 126), we start developing the ADF and test it with sample data. By the end of this chapter, we'll have a working prototype that implements the basic features of the music store application's matching component. In Chapter 6, "Completing the Application Prototype: Scheduled Subscriptions and Application State," we'll complete the prototype by implementing the more advanced features and then test the complete prototype from end to end.

Note

Chapters 7, 8, 9, and 10 cover the next four stages of the application development process: building a subscription management interface, event providers, content formatters, and delivery protocols. Chapters 12, 13, and 14 describe the final stages: performance tuning, deployment, and administration.