View source for Common Language Infrastructure

{{Short description|Open specification for runtime environments}}
{{Infobox technology standard
| title             = Common Language Infrastructure
| status            = Published
| year_started      = {{Start date and age|2000}}
| version           = Sixth edition
| version_date      = {{Start date and age|2012|06}}
| organization      = '''Developed by:''' [[Microsoft]], [[Hewlett-Packard]], [[Intel]], and others<br />
'''Standardized by:''' [[Ecma International|Ecma]], [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]]
| related_standards = 
| abbreviation      = CLI
| domain            = Common Language ([[Cross-platform]])
| website           = {{URL|https://www.ecma-international.org/publications-and-standards/standards/ecma-335/|ECMA-335}},<br />{{URL|https://www.iso.org/standard/58046.html|ISO/IEC 23271}}
| long_name         = ISO/IEC 23271:2012(E)
| first_published   = {{Start date and age|2001}} (Ecma) and {{Start date and age|2003}} (ISO/IEC)
| committee         = [[ISO/IEC JTC 1/SC 22]]
| license           = [[Reasonable and non-discriminatory licensing|RAND]]
}}
The '''Common Language Infrastructure''' ('''CLI''') is an open [[specification]] and [[technical standard]] originally developed by [[Microsoft]] and standardized by [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]] ('''ISO/IEC 23271''') and [[Ecma International]] ('''ECMA 335''')<ref name="iso_iec_23271_2012">{{cite web| url = http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=58046| title = ISO/IEC 23271:2012 - Information technology -- Common Language Infrastructure (CLI) |website=ISO |url-status=live |archive-url=https://web.archive.org/web/20230702003946/https://www.iso.org/standard/58046.html |archive-date= Jul 2, 2023 }}</ref><ref name="ecma_355_2012">{{cite web| url = https://www.ecma-international.org/publications-and-standards/standards/ecma-335/| title = ECMA-335 |issue=6th edition |date=June 2012 |website=ECMA International |url-status=live |archive-url=https://web.archive.org/web/20231016101943/https://www.ecma-international.org/publications-and-standards/standards/ecma-335/ |archive-date= Oct 16, 2023 }}</ref> that describes executable code and a runtime environment that allows [[List of CLI languages|multiple high-level languages]] to be used on different [[Computing platform|computer platforms]] without being rewritten for specific architectures. This implies it is platform agnostic. The [[.NET Framework]], [[.NET]] and [[Mono (software)|Mono]] are implementations of the CLI.
The [[metadata]] format is also used to specify the [[API]] definitions exposed by the [[Windows Runtime]].<ref>{{cite web| url = https://www.microsoftpressstore.com/articles/article.aspx?p=2199428&seqNum=3| title = Introduction to Advanced Windows Store App Development using HTML5 and JavaScript |website=Microsoft Press Store |date=Oct 15, 2013 |url-status=live |archive-url=https://web.archive.org/web/20230330075408/https://www.microsoftpressstore.com/articles/article.aspx?p=2199428&seqNum=3 |archive-date= Mar 30, 2023 }}</ref><ref>{{cite web| url = https://tirania.org/blog/archive/2011/Sep-15.html| title = WinRT demystified |first1=Miguel |last1=de Icaza |date=15 Sep 2011 |url-status=live |archive-url=https://web.archive.org/web/20231130221232/https://tirania.org/blog/archive/2011/Sep-15.html |archive-date= Nov 30, 2023 }}</ref>

==Overview==
[[File:Overview of the Common Language Infrastructure 2015.svg|thumb|280px|Visual overview of the Common Language Infrastructure (CLI)]]
Among other things, the CLI specification describes the following five aspects:

;The [[Common Type System]] (CTS)
:A set of [[data type]]s and operations that are shared by all CTS-compliant [[programming language]]s.
;The [[Metadata (CLI)|Metadata]]
:Information about program structure is [[Language-independent specification|language-agnostic]], 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 CLS, a subset of the CTS, are rules to which components developed with/for the supported languages must adhere.
:They apply to consumers (developers who are programmatically accessing a component that is CLS-compliant), frameworks (developers who are using a language compiler to create CLS-compliant libraries), and extenders (developers who are creating a tool such as a language compiler or a code parser that creates CLS-compliant components).
;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]] (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.
:In the CLI standard initially developed by Microsoft, the VES is implemented by the [[Common Language Runtime]] (CLR).

;The [[Standard Libraries (CLI)|Standard Libraries]]
:A set of libraries providing many common functions, such as file reading and writing. Their core is the [[Standard Libraries (CLI)#Base Class Library|Base Class Library]] (BCL).

==Standardization and licensing==
In August 2000, [[Microsoft]], [[Hewlett-Packard]], [[Intel]], and others worked to standardize CLI. By December 2001, it was ratified by the [[Ecma International|Ecma]], with [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|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 licensing|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 (software)|Mono]]. {{as of|2013|January}}, neither Microsoft nor its partners have identified any patents essential to CLI implementations subject to RAND terms.{{cn|date=October 2024}}

{{as of|2009|July}},<ref>{{Cite web
|url=http://port25.technet.com/archive/2009/07/06/the-ecma-c-and-cli-standards.aspx
|title=The Ecma C# and CLI Standards 
|website=Port 25
|first1=Peter |last1=Galli
|date=2009-07-06
|access-date=September 26, 2009
|archive-url=https://web.archive.org/web/20090709232640/http://port25.technet.com/archive/2009/07/06/the-ecma-c-and-cli-standards.aspx
|archive-date=July 9, 2009
|url-status=dead
}}</ref> [[Microsoft]] added [[C Sharp (programming language)|C#]] and CLI to the list of specifications that the [[Microsoft Community Promise]] applies to,<ref>{{Cite web |last=v-alje |title=[MS-DEVCENTLP]: Microsoft Community Promise |url=https://learn.microsoft.com/en-us/openspecs/dev_center/ms-devcentlp/8b8d1b7a-a10a-4667-9558-6d9c43adf60d |access-date=2023-05-01 |website=Microsoft Learn |date=March 16, 2023 |language=en-us}}</ref> 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.<ref name="iso_iec_23271_2012"/><ref name="ecma_355_2012"/>

==Implementations==
*[[.NET Framework]] 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]]
*[[.NET Compact Framework]] is Microsoft's commercial implementation of the CLI for portable devices and [[Xbox 360]].
*[[.NET Micro Framework]] is an open source implementation of the CLI for resource-constrained devices.
*[[Mono (software)|Mono]] is an alternative open source implementation of CLI and accompanying technologies, mainly used for mobile and game development.
*[[DotGNU]] is a decommissioned part of the GNU Project started in January 2001 that aimed to provide a [[free and open source software]] alternative to Microsoft's [[.NET Framework]].

==See also==
*[[Standard Libraries (CLI)]]
*[[List of CLI languages]]
*[[.NET Standard]]

==Notes==
{{Reflist}}

==References==
*{{Cite web
|title = Standard ECMA-335, Common Language Infrastructure (CLI)
|work = Ecma International
|url = https://www.ecma-international.org/publications-and-standards/standards/ecma-335/
|access-date = November 1, 2023
}}
*{{Cite web
|title = ISO/IEC 23271, Common Language Infrastructure
|work = ISO/IEC
|url = http://www.iso.org/iso/en/CatalogueDetailPage.CatalogueDetail?CSNUMBER=42927
|access-date = September 27, 2006
}}
*{{Cite web
|title = Ecma C# and Common Language Infrastructure Standards
|work = Microsoft Corporation
|url = http://msdn.microsoft.com/en-us/netframework/aa569283.aspx
|access-date = October 13, 2009
}}
*{{Cite web
|title = Language independence and language-independent components
|work = Microsoft Learn
|date = December 21, 2022
|url = https://learn.microsoft.com/en-us/dotnet/standard/language-independence
|access-date = May 19, 2023
}}

==External links==
*{{Official|https://www.iso.org/standard/58046.html|ISO/IEC 23271:2012 Information technology — Common Language Infrastructure (CLI)}}

{{Common Language Infrastructure}}
{{Ecma International Standards}}
{{ISO standards}}

{{Use mdy dates|date=January 2019}}
{{Use American English|date=January 2019}}
[[Category:Common Language Infrastructure| ]]
[[Category:Ecma standards]]
[[Category:IEC standards]]
[[Category:ISO standards]]