An Overview of the .NET Framework

The .NET Framework covers all the layers of software development above the operating system level. It provides the richest level of integration among presentation technologies, component technologies, and data technologies ever seen on a Microsoft, or perhaps any, platform. The entire architecture has been created to make it as easy to develop Internet applications as it is to develop desktop applications.

The .NET Framework actually “wraps” the operating system, insulating software developed with .NET from most operating system specifics such as file handling and memory allocation. This prepares for a possible future in which the software developed for .NET is portable to a wide variety of hardware and operating system foundations.

The major components of the .NET Framework 3.0 are shown in Figure 1-1.

.NET Framework Classes for External Interface
ASP.NET	Windows Forms	Windows Presentation Foundation		Windows Communication Foundation
Web Forms	Controls and Forms
Web Services	Drawing	Pages, Animation, etc.		Pipelines, Endpoints, etc.
.NET Framework Base Classes for Internal and Local Use
ADO.NET	XML	Threading	IO	Workflow
Component Model	Security	Diagnostics	Exceptions	Etc.
Common Language Runtime
Memory Management	Common Type System	Lifecycle Monitoring		JIT Compilers,etc.

Open table as spreadsheet

Figure 1-1

The framework starts all the way down at the memory management and component loading level and goes all the way up to multiple ways of rendering user and program interfaces. In between, there are layers that provide just about any system-level capability that a developer would need.

At the base is the common language runtime, often abbreviated to CLR. This is the heart of the .NET Framework - it is the engine that drives key functionality. It includes, for example, a common system of datatypes. These common types, plus a standard interface convention, make cross-language inheritance possible. In addition to allocation and management of memory, the CLR also does reference tracking for objects and handles garbage collection.

The middle layer includes the next generation of standard system services, such as classes that manage data and Extensible Markup Language (XML). These services are brought under control of the framework, making them universally available and making their usage consistent across languages.

The top layer includes user and program interfaces. There are four major ways of providing an interface from within .NET to entities outside .NET:

Open table as spreadsheet

Technique	Description
ASP.NET	Provides browser-based user interfaces with Web Forms and system-to-system interface over the Web with Web Services
Windows Forms	Provides local forms-based interfaces, which can be Internet enabled with Web Services or Windows Communication Foundation (below). Based on the Windows Graphic Device Interface (GDI) kernel.
Windows Presentation Foundation	Provides vector-based user interfaces with a high degree of interaction. Based on DirectX technologies.
Windows Communication Foundation	Provides a highly flexible and configurable interface from system to system or process to process. Includes support for security, transactions, and other communication necessities.

All of these interfacing capabilities are available to any language based on the .NET platform, including, of course, Visual Basic 2005.