Types of Framework Applications

You can use Visual Studio .NET 2003 and the .NET Framework to develop the following types of applications and services:

• Windows Forms Smart Client Applications

• ASP.NET-based applications (Web-based applications)

• Extensible Markup Language (XML) Web services

• Windows Services

• Console applications

• Scripted or hosted applications

We will discuss each of these in turn:

Windows Forms Smart Client Applications

In Windows Forms Smart Client applications, the logic and code used to build the GUI runs on the client computer. Windows Forms controls and menus are actually .NET Framework classes, as are the Windows Forms themselves. In addition, display effects, such as colors, borders, sizes, and positions are all controlled by accessing classes and enumerations from the .NET Framework class library.

Windows Forms Smart Client applications provide the following benefits:

• A rich user interface

• Full access to the local disk and local application programming interfaces (APIs)

• Elimination of network latency (since the application runs on the client machine)

• Multiple deployment options

• Off-line application support

• Offloading of processing to the client machine

• Ability to interact with other locally installed applications

ASP.NET Applications (Web-based Applications)

Much of the logic and code used to build the user interface for a Microsoft ASP.NET application resides (and runs) on a Web server, rather than on the computer at which the user is sitting. The browser-based GUI is dynamically built by your ASP.NET application, which transmits HTML to the browser. The GUI may be supplemented with some client-side script to provide ease of usability, increased responsiveness, data-entry validation, and dynamic display effects, but the bulk of the interface is controlled by server-based code to which the client Web browser does not have direct access. In effect, the client uses HTML, supplemented by dynamic HTML (DHTML), to present the user interface. Although the server-side code depends on the .NET Framework to build the GUI, it produces browser-agnostic HTML.

ASP.NET applications may also include Windows Forms user controls. These are assemblies referenced from Web pages that are downloaded to the user's computer and executed upon demand. These controls can provide extra functionality to your application, much like Microsoft ActiveX controls hosted in a Web browser did in the past.

ASP.NET applications provide the following benefits:

• Processing handled by the server machine.

• Some local processing through Windows Forms user controls.

• Use of Dynamic HTML to create user interface features.

XML Web Services

XML Web services provide a standards-based platform for application integration. .NET-based applications may be constructed to use multiple XML Web services from various sources that work together regardless of where they reside or how they were implemented. As well as working with each other, XML Web services can also be consumed by both Windows Forms and ASP.NET applications. There are three major differences between Web services and traditional Web applications:

• Web services use SOAP messages instead of MIME messages.

• Web services are not HTTP specific.

• Web services provide metadata describing the messages they produce and consume.

Windows Services

Windows Services are applications which generally run in the background and are managed by the Service Control Manager. They can be started automatically at system boot, by a user through the Services MMC snap-in, or by another application.

Windows Services have their own processes, and start in a predefined security context that is independent of the logged on user. Windows Services do not usually have a user interface.

Note

Windows Services will not run on Windows 9x or Windows ME.

Console Applications

A console application provides character-mode support in a text-only window. Unlike a Windows Forms application, it is not forms driven, although Windows Forms can be called from a console application.

The Framework provides classes that support output and input from console windows with standard I/O behaviors.

Scripted or Hosted Applications

Scripted or hosted applications use existing hosting features of an operating system or application to run, meaning that the code can be interpreted at run time and does not have to be precompiled. The most common examples are Visual Basic Scripting Host (*.vbs) and Windows Scripting Host (*.wsf) applications. While these types of applications performs specific functions, the commonly do not have much if any user interface. These types of applications can often be incorporated into other applications to perform specific functions.