Summary

A SQL-NS application consists of several functional components. Some of these components, including the event providers and the subscription management interface, deal with getting data into the application. Other components, such as the content formatters and delivery protocols, deal with the output of the application. At the core of the application is a matching component that processes the input data and produces the final notifications as output. In this matching component, the core logic of the application is implemented.

The most effective way to build an application is to begin by designing and prototyping the matching component. In the design stage, you define the key elements of the application. In the prototype stage, you implement the design and test it with sample data. SQL-NS provides facilities you can use to get data in and out of the application before you build the real input and output components your application will use in its final form. Using the components provided by SQL-NS at the prototype stage allows you to focus on the implementation of the core logic and not be distracted by the mechanics of the application's input and output interfaces.

Building the prototype involves writing the application's ADF. The ADF defines the schema of the input and output data and the logic used to generate notifications. Rather than trying to build the whole ADF all at once, it's much easier to build it in stages. Starting from a skeleton ADF, you can add one piece of functionality at a time and compile it incrementally with the SQL-NS update tools. As you add each piece of functionality, you can test it in isolation. When the prototype is complete, it's a good idea to recompile the whole application from scratch and test it in an end-to-end scenario.

In this chapter, we designed and prototyped the basic features of a sample application: a notification service for a music store. In the upcoming chapters, we'll continue the development process on the music store application.

Note

In Chapter 6, we will continue to work with the instance created in this chapter. For this reason, do not delete this chapter's instance as you've done in other chapters. I've provided full cleanup instructions at various points later in this book for use when you're finished working with the instance.