Common Language Infrastructure
Encyclopedia
The Common Language Infrastructure (CLI) is an open specification developed by Microsoft
and standardized by ISO and ECMA that describes the executable code and runtime environment that form the core of the Microsoft .NET Framework
and the free and open source
implementations Mono
and Portable.NET
. The specification defines an environment that allows multiple high-level languages to be used on different computer platforms without being rewritten for specific architectures.
Among other things, the CLI specification describes the following four aspects:-
The Common Type System
(CTS) : A set of data type
s and operations that are shared by all CTS-compliant programming language
s.
Metadata
: Information about program structure is language-agnostic, so that it can be referenced between languages and tools, making it easy to work with code written in a language you are not using.
Common Language Specification (CLS) : A set of base rules to which any language targeting the CLI should conform in order to interoperate with other CLS-compliant languages. The CLS rules define a subset of the Common Type System.
Virtual Execution System
(VES) : The VES loads and executes CLI-compatible programs, using the metadata to combine separately generated pieces of code at runtime.
All compatible languages compile to Common Intermediate Language
(CIL), which is an intermediate language
that is abstracted from the platform hardware. When the code is executed, the platform-specific VES will compile the CIL to the machine language according to the specific hardware and operating system.
, Hewlett-Packard
, Intel, and others worked to standardize CLI. By December 2001, it was ratified by the ECMA
, with ISO
standardization following in April 2003.
Microsoft and its partners hold patents for CLI. ECMA and ISO require that all patents essential to implementation be made available under "reasonable and non-discriminatory (RAND) terms
", but interpretation of this has led to much controversy, particularly in the case of Mono .
As of July 2009. Microsoft
applied C# and CLI under the Community Promise, so anyone can safely implement those standards without fearing a patent lawsuit.
is statically typed.
The Dynamic Language Runtime
is an ongoing effort to bring this support to the CLR
.
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
and standardized by ISO and ECMA that describes the executable code and runtime environment that form the core of the Microsoft .NET Framework
.NET Framework
The .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
and the free and open source
Free and open source software
Free and open-source software or free/libre/open-source software is software that is liberally licensed to grant users the right to use, study, change, and improve its design through the availability of its source code...
implementations Mono
Mono (software)
Mono, pronounced , is a free and open source project led by Xamarin to create an Ecma standard compliant .NET-compatible set of tools including, among others, a C# compiler and a Common Language Runtime....
and Portable.NET
Portable.NET
Part of the DotGNU project, Portable.NET is a free software and open source software initiative aiming to build a portable toolchain and runtime for Common Language Infrastructure applications. The project focuses on compatibility with the ECMA-334 and ECMA-335 standards and support for .NET's...
. The specification defines an environment that allows multiple high-level languages to be used on different computer platforms without being rewritten for specific architectures.
Overview
The Common Type System
Common Type System
In Microsoft's .NET Framework, the Common Type System is a standard that specifies how Type definitions and specific values of Types are represented in...
(CTS) : A set of data type
Data type
In computer programming, a data type is a classification identifying one of various types of data, such as floating-point, integer, or Boolean, that determines the possible values for that type; the operations that can be done on values of that type; the meaning of the data; and the way values of...
s and operations that are shared by all CTS-compliant programming language
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
s.
Metadata
.NET metadata
.NET metadata, in the Microsoft .NET framework, refers to certain data structures embedded within the Common Intermediate Language code that describes the high-level structure of the code. Metadata describes all classes and class members that are defined in the assembly, and the classes and class...
: Information about program structure is language-agnostic, so that it can be referenced between languages and tools, making it easy to work with code written in a language you are not using.
Common Language Specification (CLS) : A set of base rules to which any language targeting the CLI should conform in order to interoperate with other CLS-compliant languages. The CLS rules define a subset of the Common Type System.
Virtual Execution System
Virtual Execution System
The Virtual Execution System provides an environment for executing managed code. It provides direct support for a set of built-in data types, defines a hypothetical machine with an associated machine model and state, a set of control flow constructs, and an exception handling model...
(VES) : The VES loads and executes CLI-compatible programs, using the metadata to combine separately generated pieces of code at runtime.
All compatible languages compile to Common Intermediate Language
Common Intermediate Language
Common Intermediate Language is the lowest-level human-readable programming language defined by the Common Language Infrastructure specification and is used by the .NET Framework and Mono...
(CIL), which is an intermediate language
Intermediate language
In computer science, an intermediate language is the language of an abstract machine designed to aid in the analysis of computer programs. The term comes from their use in compilers, where a compiler first translates the source code of a program into a form more suitable for code-improving...
that is abstracted from the platform hardware. When the code is executed, the platform-specific VES will compile the CIL to the machine language according to the specific hardware and operating system.
Standardization and licensing
In August 2000, MicrosoftMicrosoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
, Hewlett-Packard
Hewlett-Packard
Hewlett-Packard Company or HP is an American multinational information technology corporation headquartered in Palo Alto, California, USA that provides products, technologies, softwares, solutions and services to consumers, small- and medium-sized businesses and large enterprises, including...
, Intel, and others worked to standardize CLI. By December 2001, it was ratified by the ECMA
Ecma International
Ecma International is an international, private non-profit standards organization for information and communication systems. It acquired its name in 1994, when the European Computer Manufacturers Association changed its name to reflect the organization's global reach and activities...
, with ISO
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
standardization following in April 2003.
Microsoft and its partners hold patents for CLI. ECMA and ISO require that all patents essential to implementation be made available under "reasonable and non-discriminatory (RAND) terms
Reasonable and Non Discriminatory Licensing
Reasonable and non-discriminatory licensing is a type of licensing typically used during standardization processes. When joining a standardization body, companies normally agree that if they receive any patents on technologies which become essential to the standard they agree to allow other...
", but interpretation of this has led to much controversy, particularly in the case of Mono .
As of July 2009. Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
applied C# and CLI under the Community Promise, so anyone can safely implement those standards without fearing a patent lawsuit.
Support for dynamic languages
The Common Language Infrastructure currently has no built-in support for Dynamically typed languages because the existing Common Intermediate LanguageCommon Intermediate Language
Common Intermediate Language is the lowest-level human-readable programming language defined by the Common Language Infrastructure specification and is used by the .NET Framework and Mono...
is statically typed.
The Dynamic Language Runtime
Dynamic Language Runtime
The Dynamic Language Runtime from Microsoft is an ongoing effort to bring a set of services that run on top of the Common Language Runtime and provides language services for several different dynamic languages...
is an ongoing effort to bring this support to the CLR
Common Language Runtime
The Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
.
Implementations
- The .NET Framework.NET FrameworkThe .NET Framework is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages which allows language interoperability...
is built on the Common Language RuntimeCommon Language RuntimeThe Common Language Runtime is the virtual machine component of Microsoft's .NET framework and is responsible for managing the execution of .NET programs. In a process known as just-in-time compilation, the CLR compiles the intermediate language code known as CIL into the machine instructions...
, Microsoft's commercial implementation of the CLI for desktop and server systems, and also encompasses a large collection of programming frameworks and libraries. - Shared Source Common Language InfrastructureShared Source Common Language InfrastructureThe Shared Source Common Language Infrastructure , previously codenamed Rotor, is Microsoft's shared source implementation of the CLI, the core of .NET. Although the SSCLI is not suitable for commercial use due to its license, it does make it possible for programmers to examine the implementation...
is a reference implementation of the CLI available from Microsoft, under the Shared sourceShared sourceShared source is an umbrella term covering some of Microsoft's legal mechanisms for software source code distribution. Microsoft's Shared Source Initiative, launched in May 2001, includes a spectrum of technologies and licenses...
licensing program. - .NET Compact Framework.NET Compact FrameworkThe Microsoft .NET Compact Framework is a version of the .NET Framework that is designed to run on resource constrained mobile/embedded devices such as personal digital assistants , mobile phones, factory controllers, set-top boxes, etc...
is Microsoft's commercial implementation of the CLI for portable devices and Xbox 360Xbox 360The Xbox 360 is the second video game console produced by Microsoft and the successor to the Xbox. The Xbox 360 competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles...
. - Microsoft SilverlightMicrosoft SilverlightMicrosoft Silverlight is an application framework for writing and running rich Internet applications, with features and purposes similar to those of Adobe Flash. The run-time environment for Silverlight is available as a plug-in for web browsers running under Microsoft Windows and Mac OS X...
, an implementation for use in web browsers - for Microsoft WindowsMicrosoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
and Mac OS XMac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
. - Mono development platformMono (software)Mono, pronounced , is a free and open source project led by Xamarin to create an Ecma standard compliant .NET-compatible set of tools including, among others, a C# compiler and a Common Language Runtime....
is an open sourceOpen sourceThe term open source describes practices in production and development that promote access to the end product's source materials. Some consider open source a philosophy, others consider it a pragmatic methodology...
implementation of CLI and accompanying technologies, sponsored by XamarinXamarinXamarin is a company created in May 2011 by the engineers that created Mono, MonoTouch and Mono for Android which are cross-platform implementations of the Common Language Infrastructure and Common Language Specifications ....
. - Portable.NETPortable.NETPart of the DotGNU project, Portable.NET is a free software and open source software initiative aiming to build a portable toolchain and runtime for Common Language Infrastructure applications. The project focuses on compatibility with the ECMA-334 and ECMA-335 standards and support for .NET's...
, part of the dotGNUDotGNUDotGNU is a part of the GNU Project that aims to provide a free software replacement for Microsoft's .NET Framework by Free Software Foundation...
project, is a Free SoftwareFree softwareFree software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
implementation of ECMA-335 by Free Software FoundationFree Software FoundationThe Free Software Foundation is a non-profit corporation founded by Richard Stallman on 4 October 1985 to support the free software movement, a copyleft-based movement which aims to promote the universal freedom to create, distribute and modify computer software...
. - VMKit part of Low Level Virtual MachineLow Level Virtual MachineThe Low Level Virtual Machine is a compiler infrastructure written in C++ that is designed for compile-time, link-time, run-time, and "idle-time" optimization of programs written in arbitrary programming languages...
toolkit as of version 2.3. Implements very incomplete and alpha stage support of a Virtual Execution SystemVirtual Execution SystemThe Virtual Execution System provides an environment for executing managed code. It provides direct support for a set of built-in data types, defines a hypothetical machine with an associated machine model and state, a set of control flow constructs, and an exception handling model...
. It is based on DotGNUDotGNUDotGNU is a part of the GNU Project that aims to provide a free software replacement for Microsoft's .NET Framework by Free Software Foundation...
, Portable.NETPortable.NETPart of the DotGNU project, Portable.NET is a free software and open source software initiative aiming to build a portable toolchain and runtime for Common Language Infrastructure applications. The project focuses on compatibility with the ECMA-334 and ECMA-335 standards and support for .NET's...
corelib and class libraries.