The previous chapters have used console applications to demonstrate C# and the CLR. Although console applications can be implemented simply, it is time to turn your attention to the reason you're learning the C# language in the first place: building Windows and web applications.
In the early days of Windows computing, an application ran on a desktop, in splendid isolation. Over time, developers found it beneficial to spread their applications across a network, with the user interface on one computer and a database on another. This division of responsibilities, or partitioning of an application, came to be called two-tier or client-server application development. Later, three-tier or n-tier approaches emerged as developers began to use web servers to host business objects that could handle the database access on behalf of clients.
When the Web first came along, there was a clear distinction between Windows applications and web applications. Windows applications ran on the desktop or a local area network (LAN), and web applications ran on a distant server and were accessed by a browser. This distinction is now being blurred as Windows applications reach out to the Web for services. Many new applications consist of logic running on a client, a database server, and remote third-party computers located on the Web. Traditional desktop applications such as Excel or Outlook are now able to integrate data retrieved through web connections seamlessly, and web applications can distribute some of their processing to client-side components.
The primary remaining distinction between a Windows application and a web application might be this: who owns the user interface. Will your application use a browser to display its user interface, or will the UI be built into the executable running on the desktop?
There are enormous advantages to web applications, starting with the obvious: they can be accessed from any browser that can connect to the server. In addition, updates can be made at the server, without the need to distribute new dynamic link libraries (DLLs) to your customers.
On the other hand, if your application derives no benefit from being on the Web, you might find that you can achieve greater control over the look and feel of your application or that you can achieve better performance by building a desktop application.
.NET offers closely related, but distinguishable, suites of tools for building Windows or web applications. Both are based on forms, with the premise that many applications have user interfaces centered on interacting with the user through forms and controls, such as buttons, listboxes, text, and so forth.
The tools for creating web applications are called Web Forms and are considered in Chapter 15. The tools for creating Windows applications are called Windows Forms and are the subject of this chapter.
In the following pages, you will learn how to create a simple Windows Form using either a text editor such as Notepad, or the Design tool in Visual Studio .NET. Next you will build a more complex Windows application using Visual Studio, the Windows Forms framework, and a number of C# programming techniques you learned in earlier chapters. The chapter concludes with a brief introduction to Documentation Comments, a new XML-facilitated means to document applications, and an introduction to the deployment of .NET applications.