View source for Interface description language

{{Short description|Computer language used to describe a software component's interface}}
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[[File:Component-based-Software-Engineering-example2.png|thumb|right|Representation of different software components for performing a hypothetical holiday reservation in [[Unified Modeling Language|UML]]]]

An '''interface description language''' or '''interface definition language''' ('''IDL''') is a generic term for a language that lets a program or object written in one language communicate with another program written in an unknown language. IDLs are usually used to describe [[data type]]s and interfaces in a [[Language-independent specification|language-independent]] way, for example, between those written in [[C++]] and those written in [[Java (programming language)|Java]].

IDLs are commonly used in [[remote procedure call]] software. In these cases the machines at either end of the ''link'' may be using different [[operating system]]s and computer languages. IDLs offer a bridge between the two different systems.

Software systems based on IDLs include [[Sun Microsystems|Sun's]] [[ONC RPC]], [[The Open Group]]'s [[Distributed Computing Environment]], [[IBM]]'s [[System Object Model]], the [[Object Management Group]]'s [[CORBA]] (which implements OMG IDL, an IDL based on DCE/RPC) and [[Data Distribution Service]], [[Mozilla]]'s [[XPCOM]], [[Microsoft]]'s [[Microsoft RPC]] (which evolved into [[Component Object Model|COM]] and [[Distributed Component Object Model|DCOM]]), [[Facebook]]'s [[Apache Thrift|Thrift]] and [[Web Services Description Language|WSDL]] for Web services.

== Examples ==
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* [https://developer.android.com/guide/components/aidl AIDL]: [[Java (programming language)|Java]]-based, for [[Android (operating system)|Android]]; supports local and remote procedure calls, can be accessed from native applications by calling through [[Java Native Interface]] (JNI)
* [[Apache Thrift]]: from [[Apache Software Foundation|Apache]], originally developed by [[Facebook]]
* [[Apache Avro|Avro IDL]]: for the Apache Avro system
* [[ASN.1]]
* [[Cap'n Proto]]: created by its former maintainer, avoids some of the perceived shortcomings of [[Protocol Buffers]].
* [[Concise Data Definition Language]] (CDDL, RFC 8610):<ref>{{Cite journal|title=Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures|url=https://www.rfc-editor.org/rfc/rfc8610|access-date=2022-05-24|website=RFC Editor|year=2019 |doi=10.17487/RFC8610 |language=en|last1=Birkholz |first1=H. |last2=Vigano |first2=C. |last3=Bormann |first3=C. |s2cid=195857027 |url-access=subscription }}</ref> A Notation for [[CBOR]] and [[JSON]] data structures
* [[CortoScript]]: Describe data and/or interfaces for systems that require [[Semantic interoperability]]
* [[Etch (protocol)|Etch]]: Cisco's Etch Cross-platform Service Description Language
* [[Extensible Data Notation]] (EDN): [[Clojure]] data format, similar to JSON
*[[FlatBuffers]]: Serialization format from [[Google]] supporting zero-copy deserialization
* [[Franca IDL]]: the open-source Franca interface definition language
* [https://fuchsia.dev/fuchsia-src/get-started/learn/fidl/fidl FIDL]: Interface description language for the [[Fuchsia (operating system)|Fuchsia Operating System]] designed for writing app components in [[C (programming language)|C]], [[C++]], [[Dart (programming language)|Dart]], [[Go (programming language)|Go]] and [[Rust (programming language)|Rust]].<ref>{{Cite web|title=FIDL Overview|url=https://fuchsia.dev/fuchsia-src/concepts/fidl/overview|access-date=2022-02-23|website=Fuchsia|language=en}}</ref> 
* [[IDL specification language]]: the original Interface Description Language
* [https://docs.imandra.ai/ipl IPL]: Imandra Protocol Language
* [[JSON]] Web-Service Protocol ([[JSON-WSP]])
* [[Lightweight Imaging Device Interface Language]]
* [[Microsoft Interface Definition Language]] (MIDL): the Microsoft extension of OMG IDL to add support for [[Component Object Model]] (COM) and [[Distributed Component Object Model]] (DCOM)
* [[OMG IDL]]: standardized by [[Object Management Group]], used in [[CORBA]] (for DCE/RPC services) and [[Data Distribution Service|DDS]] (for [[data modeling]]), also selected by the W3C for exposing the DOM of XML, HTML, and CSS documents
* [[OpenAPI Specification]]: a standard for [[Web API|Web APIs]], used by [[Swagger (software)|Swagger]] and other technologies. 
* [[Open Service Interface Definitions]]
* [[Protocol Buffers]]: [[Google]]'s IDL
* [[RESTful Service Description Language]] (RSDL)
* [https://smithy.io Smithy]: An AWS-invented protocol-agnostic interface definition language.
* Specification Language for [[Internet Communications Engine]] (Ice: [[Internet Communications Engine#Slice|Slice]])
* [[Universal Network Objects]]: [[OpenOffice.org]]'s component model
* [[Web Application Description Language]] (WADL)
* [[Web IDL]] by [[WHATWG]]: can be used to describe interfaces that are intended to be implemented in web browsers
* [[Web Services Description Language]] (WSDL)
* [[XCB]]: X protocol description language for [[X Window System]]
* Cross Platform Interface Description Language ([[XPIDL]]): Mozilla's way to specify XPCOM interfaces

== See also ==
* [[Component-based software engineering]]
* [[Interface-based programming]]
* [[Java Interface Definition Language]]
* [[List of computing and IT abbreviations]]
* [[Universal Interface Language]]
* [[User interface markup language]]

==References==
{{Reflist}}

== External links ==
* [https://resources.sei.cmu.edu/library/asset-view.cfm?assetid=5939 Documenting Software Architecture: Documenting Interfaces] (PDF)
* [https://www.omg.org/spec/IDL OMG Specification of OMG IDL]
* [http://www.omg.org/gettingstarted/omg_idl.htm OMG Tutorial on OMG IDL]

[[Category:Data modeling languages]]
[[Category:Remote procedure call]]
[[Category:Specification languages]]
[[Category:Domain-specific programming languages]]