The Common Language Infrastructure (CLI) is an open

specification A specification often refers to a set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard. There are different types of technical or engineering specificati ...

and

technical standard A technical standard is an established norm or requirement for a repeatable technical task which is applied to a common and repeated use of rules, conditions, guidelines or characteristics for products or related processes and production methods, ...

originally developed by

Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...

and standardized by

ISO ISO is the most common abbreviation for the International Organization for Standardization. ISO or Iso may also refer to: Business and finance * Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007 * Iso ...

/ IEC (ISO/IEC 23271) and

Ecma International Ecma International () is a nonprofit standards organization for information and communication systems. It acquired its current name in 1994, when the European Computer Manufacturers Association (ECMA) changed its name to reflect the organization ...

(ECMA 335) that describes executable code and a runtime environment that allows multiple high-level languages to be used on different computer platforms without being rewritten for specific architectures. This implies it is platform agnostic. The

.NET Framework The .NET Framework (pronounced as "''dot net"'') is a proprietary software framework developed by Microsoft that runs primarily on Microsoft Windows. It was the predominant implementation of the Common Language Infrastructure (CLI) until bein ...

, .NET and Mono are implementations of the CLI. The metadata format is also used to specify the

API An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...

definitions exposed by the

Windows Runtime Windows Runtime (WinRT) is a platform-agnostic component and application architecture first introduced in Windows 8 and Windows Server 2012 in 2012. It is implemented in C++ and officially supports development in C++ (via C++/WinRT, C++/CX or ...

Overview

Among other things, the CLI specification describes the following four aspects: ;The

Common Type System In Microsoft's .NET Framework, the Common Type System (CTS) is a standard that specifies how type definitions and specific values of types are represented in computer memory. It is intended to allow programs written in different programming langu ...

(CTS) :A set of data types and operations that are shared by all CTS-compliant

programming language A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language. The description of a programming ...

s. ;The Metadata :Information about program structure is

language-agnostic Language-agnostic programming or scripting (also called language-neutral, language-independent, or cross-language) is a software paradigm in which no particular language is promoted. In introductory instruction, the term refers to teaching princip ...

, so that it can be referenced between languages and tools, making it easy to work with code written in a language the developer is not using. ;The Common Language Specification (CLS) :The CLI should conform with the set of base rules to which any language targeting, since that language should interoperate with other CLS-compliant languages. The CLS rules are a subset of the Common Type System. ;The 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 Common Intermediate Language (CIL), formerly called Microsoft Intermediate Language (MSIL) or Intermediate Language (IL), is the intermediate language binary instruction set defined within the Common Language Infrastructure (CLI) specification. ...

(CIL), which is an

intermediate language An intermediate representation (IR) is the data structure or code used internally by a compiler or virtual machine to represent source code. An IR is designed to be conducive to further processing, such as optimization and translation. A " ...

that is abstracted from the platform hardware. When the code is executed, the platform-specific VES will compile the CIL to the

machine language In computer programming, machine code is any low-level programming language, consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). Each instruction causes the CPU to perform a very ...

according to the specific hardware and operating system.

Standardization and licensing

In August 2000,

, Hewlett-Packard,

Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...

, and others worked to standardize CLI. By December 2001, it was ratified by the Ecma, with

/ IEC standardization following in April 2003. Microsoft and its partners hold patents for CLI. Ecma and ISO/IEC require that all patents essential to implementation be made available under " reasonable and non-discriminatory (RAND) terms." It is common for RAND licensing to require some royalty payment, which could be a cause for concern with Mono. As of January 2013, neither Microsoft nor its partners have identified any patents essential to CLI implementations subject to RAND terms. As of July 2009,

added C# and CLI to the list of specifications that the

Microsoft Community Promise The Microsoft Open Specification Promise (or OSP) is a promise by Microsoft, published in September 2006, to not assert its patents, in certain conditions, against implementations of a certain list of specifications. The OSP is not a licence, but r ...

applies to, so anyone can safely implement specified editions of the standards without fearing a patent lawsuit from Microsoft. To implement the CLI standard requires conformance to one of the supported and defined profiles of the standard, the minimum of which is the kernel profile. The kernel profile is actually a very small set of types to support in comparison to the well known core library of default .NET installations. However, the conformance clause of the CLI allows for extending the supported profile by adding new methods and types to classes, as well as deriving from new namespaces. But it does not allow for adding new members to interfaces. This means that the features of the CLI can be used and extended, as long as the conforming profile implementation does not change the behavior of a program intended to run on that profile, while allowing for unspecified behavior from programs written specifically for that implementation. In 2012, Ecma and ISO/IEC published the new edition of the CLI standard, which is not covered by the Community Promise.

Implementations

is Microsoft's original commercial implementation of the CLI. It only supports Windows. It was superseded by .NET in November 2020. * .NET, previously known as .NET Core, is the free and open-source multi-platform successor to .NET Framework, released under the

MIT License The MIT License is a permissive free software license originating at the Massachusetts Institute of Technology (MIT) in the late 1980s. As a permissive license, it puts only very limited restriction on reuse and has, therefore, high license comp ...

.NET Compact Framework The Microsoft .NET Compact Framework (.NET CF) is a version of the .NET Framework that is designed to run on resource constrained mobile/embedded devices such as personal digital assistants (PDAs), mobile phones, factory controllers, set-top box ...

is Microsoft's commercial implementation of the CLI for portable devices and

Xbox 360 The Xbox 360 is a home video game console developed by Microsoft. As the successor to the original Xbox, it is the second console in the Xbox series. It competed with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generati ...

. *

.NET Micro Framework The .NET Micro Framework (NETMF) is a .NET Framework platform for resource-constrained devices with at least 512 kB of flash and 256 kB of random-access memory (RAM). It includes a small version of the .NET Common Language Runtime (CLR ...

is an open source implementation of the CLI for resource-constrained devices. * Mono is an alternative open source implementation of CLI and accompanying technologies, mainly used for mobile and game development.

Overview

Standardization and licensing

Implementations

See also

Notes

References

External links