The Microsoft .NET Framework is a software component that can be added to or is included with Microsoft Windows operating system. It provides a large body of pre-coded solutions to common program requirements, and manages the execution of programs written specifically for the framework. The .NET Framework is a key Microsoft offering, and is intended to be used by most new applications created for the Windows platform.
The pre-coded solutions that form the framework's class library cover a large range of programming needs in areas including: user interface, data access, database connectivity, cryptography, web application development, numeric algorithms, and network communications. The functions of the class library are used by programmers who combine them with their own code to produce applications.
.NET
Programs written for the .NET Framework execute in a software environment that manages the program's runtime requirements. This runtime environment, which is also a part of the .NET Framework, is known as the Common Language Runtime (CLR). The CLR provides the appearance of an application virtual machine, so that programmers need not consider the capabilities of the specific CPU that will execute the program. The CLR also provides other important services such as security mechanisms, memory management, and exception handling. The class library and the CLR together compose the .NET Framework. The framework is intended to make it easier to develop computer applications and to reduce the vulnerability of applications and computers to security threats.
It is included with Windows Server 2003 and Windows Vista, and can be installed on most older versions of Windows.
Design goals and principal features
Microsoft .NET Framework was designed with several intentions:
Interoperability - Because interaction between new and older applications is commonly required, the .NET Framework provides means to access functionality that is implemented in programs that execute outside the .NET environment. Access to COM components is provided in the System.Runtime.InteropServices and System.EnterpriseServices namespaces of the framework, and access to other functionality is provided using the P/Invoke feature.
Common Runtime Engine - Programming languages on the .NET Framework compile into an intermediate language known as the Common Intermediate Language, or CIL (formerly known as Microsoft Intermediate Language, or MSIL). In Microsoft's implementation, this intermediate language is not interpreted, but rather compiled in a manner known as just-in-time compilation (JIT) into native code. The combination of these concepts is called the Common Language Infrastructure (CLI), a specification; Microsoft's implementation of the CLI is known as the Common Language Runtime (CLR).
Language Independence - The .NET Framework introduces a Common Type System, or CTS. The CTS specification defines all possible datatypes and programming constructs supported by the CLR and how they may or may not interact with each other. Because of this feature, the .NET Framework supports development in multiple programming languages. This is discussed in more detail in the .NET languages section below.
Base Class Library - The Base Class Library (BCL), sometimes referred to as the Framework Class Library (FCL), is a library of types available to all languages using the .NET Framework. The BCL provides classes which encapsulate a number of common functions, including file reading and writing, graphic rendering, database interaction and XML document manipulation.
Simplified Deployment - Installation of computer software must be carefully managed to ensure that it does not interfere with previously installed software, and that it conforms to increasingly stringent security requirements. The .NET framework includes design features and tools that help address these requirements.
Security - .NET allows for code to be run with different trust levels without the use of a separate sandbox.
A design goal of the .NET Framework was to support platform independence. That is, a program written to use the framework should run without change on any type of computer for which the framework is implemented. However, Microsoft has only implemented the full .NET framework on the Windows operating system. Microsoft and others have implemented portions of the framework on non-Windows systems, but to date these implementations are neither complete nor widely used, so full cross-platform support has not been achieved.
Standardization and licensing
In August 2000, Microsoft, Hewlett-Packard, and Intel worked to standardize CLI and the C# programming language. By December 2001, both were ratified ECMA standards (ECMA 335 and ECMA 334). ISO followed in April 2003 (ISO/IEC 23271 and ISO/IEC 23270).
While Microsoft and their partners hold patents for CLI and C#, ECMA and ISO requires that all patents essential to implementation be made available under "reasonable and non-discriminatory (RAND) terms." In addition to meeting these terms, the companies have agreed to make the patents available royalty-free.
However, this does not apply for the part of the .NET Framework which is not covered by the ECMA/ISO standard, which includes Windows Forms, ADO.NET, and ASP.NET. Patents that Microsoft holds in these areas may deter non-Microsoft implementations of the full framework.
Future development
Microsoft has not yet made public a roadmap of the development plans for future edition of .NET framework, but has released general information regarding it. Future revisions will have better support for parallel programs, that target multi-core or distributed systems.[S. Somasegar. The world of multi and many cores. Retrieved on 2007-05-11] Technologies like PLINQ, a parallel implementation of the LINQ engine, and Concurrency and Coordination Runtime can make an appearance.
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