In this book, we'll study the concepts and skills required to successfully plan and build an enterprise application with Visual Basic. Not only will we show how to develop such an application, but we'll also show that the coding approach we take allows the solution to be easily extended and modified with the minimum of effort. To demonstrate this we'll show you how to Web-enable the application, and make use of new technologies to facilitate communication with other applications.

In order to make the most of this book, you should already be familiar with Visual Basic, and know how to build objects using Visual Basic. As we pointed out earlier, we're going to begin by exploring the programming tools that we'll need to develop enterprise applications. Thus, in Chapters 3 and 4 you'll find a refresher on Visual Basic object-oriented software and component development, while in
Chapter 5 we'll discuss the services provided by Microsoft to manage our components.

As you'll quickly come to realize, over the course of developing an enterprise application you'll have to develop an awareness of a number of different technologies to complement your VB knowledge. For example, in Chapters 10, 11, and 12 we'll be using ActiveX Data Objects (ADO) and Structured Query Language (SQL) to communicate with a SQL Server 7.0 database.

The strategy we're going to adopt to make use of these potentially unfamiliar programming concepts is to investigate the theory, and then see how it works using a simple example. We'll then, at the appropriate time, extend these concepts and demonstrate how they are used in the case study.

The case study is a complex application, and it can be downloaded from the Wrox web site at www.wrox.com. Although we're not expecting that you'll type all the code in yourself, all the code in the application can be found either in the body of the book or in Appendix A, so if you wish you can build the application as you read.

When we start to develop enterprise applications we need to pay attention to a variety of interesting issues, such as scalability, reliability and availability.