Introduction

This is the first chapter from the book Visual Basic 6 Application Development

Even if you've written only a few applications using Visual Basic (VB), you probably know how easy it makes creating small applications. VB's visual tools allow you to drag and drop user interface elements onto forms, and its integrated environment is superb for interactively writing the code that drives the application. Because there are only a few steps involved, only minimal planning is needed to successfully create an application.

However, building a large, distributed enterprise application is a complex undertaking, even when using VB. This book aims to show you how to build on your understanding of the VB language, and introduce you to the concepts and approaches required in the development of larger applications. We're going to cover a lot of ground over the next few hundred pages – we'll be showing you programming techniques, as well as introducing the systematic methods used to design, create and manage a distributed application throughout its life (the software development life cycle – SDLC).

Don't worry though; we're going to be breaking down the complexity into manageable steps. This whole book is based around developing an online banking application. We'll begin by giving you a thorough grounding in the programming approaches needed for such applications. These approaches will be demonstrated with clear, simple examples so that when we move on to the case study proper, you'll be familiar with the coding techniques used.

Initially we need to get a good handle on the differences between small VB programs, and distributed or enterprise applications. So, in this chapter, we'll look at the following topics:

• Application development

• Distributed applications

• Software development processes and why they are used

• Distributed application development using Microsoft products

• The WROBA case study

• The software requirements for making best use of this book

In particular, we'll be introducing the technologies that are used to build large, enterprise-class applications on the Windows family of operating systems. Each of these technologies will receive more detailed coverage in later chapters, so by the end of the book you'll have a clear understanding of how they are used.

Let's begin by clarifying what application development involves.