In programming and

software design Software design is the process of conceptualizing how a software system will work before it is implemented or modified. Software design also refers to the direct result of the design process the concepts of how the software will work which co ...

, a binding is an

application programming interface An application programming interface (API) is a connection between computers or between computer programs. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standard that des ...

(API) that provides

glue code In computer programming, glue code is code that allows components to interoperate that otherwise are incompatible. The adapter pattern describes glue code as a software design pattern. Glue code describes language bindings or foreign function ...

specifically made to allow a

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

to use a foreign

library A library is a collection of Book, books, and possibly other Document, materials and Media (communication), media, that is accessible for use by its members and members of allied institutions. Libraries provide physical (hard copies) or electron ...

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

service (one that is not native to that language).

Characteristics

Binding generally refers to a mapping of one thing to another. In the context of

software libraries In computing, a library is a collection of resources that can be leveraged during software development to implement a computer program. Commonly, a library consists of executable code such as compiled functions and classes, or a library can ...

, bindings are wrapper libraries that bridge two

s, so that a

written for one language can be used in another language. Many software libraries are written in

system programming language A system programming language is a programming language used for system programming; such languages are designed for writing system software, which usually requires different development approaches when compared with application software. Eds ...

s such as C or C++. To use such libraries from another language, usually of higher-level, such as

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

Common Lisp Common Lisp (CL) is a dialect of the Lisp programming language, published in American National Standards Institute (ANSI) standard document ''ANSI INCITS 226-1994 (S2018)'' (formerly ''X3.226-1994 (R1999)''). The Common Lisp HyperSpec, a hyperli ...

, Scheme,

Python Python may refer to: Snakes * Pythonidae, a family of nonvenomous snakes found in Africa, Asia, and Australia ** ''Python'' (genus), a genus of Pythonidae found in Africa and Asia * Python (mythology), a mythical serpent Computing * Python (prog ...

, or Lua, a binding to the library must be created in that language, possibly requiring recompiling the language's code, depending on the amount of modification needed. However, most languages offer a

foreign function interface A foreign function interface (FFI) is a mechanism by which a program written in one programming language can call routines or make use of services written or compiled in another one. An FFI is often used in contexts where calls are made into a bin ...

, such as Python's and

OCaml OCaml ( , formerly Objective Caml) is a General-purpose programming language, general-purpose, High-level programming language, high-level, Comparison of multi-paradigm programming languages, multi-paradigm programming language which extends the ...

's ctypes, and

Embeddable Common Lisp Embeddable Common Lisp (ECL) is a small implementation of the ANSI Common Lisp programming language that can be used stand-alone or embedded in extant applications written in C. It creates OS-native executables and libraries (i.e. Executable and ...

's cffi and uffi. For example,

bindings are used when an extant C library, written for some purpose, is to be used from Python. Another example is libsvn which is written in C to provide an API to access the

Subversion Subversion () refers to a process by which the values and principles of a system in place are contradicted or reversed in an attempt to sabotage the established social order and its structures of Power (philosophy), power, authority, tradition, h ...

software repository A software repository, or repo for short, is a storage location for Package format, software packages. Often a table of contents is also stored, along with metadata. A software repository is typically managed by source or version control, or rep ...

. To access Subversion from within Java code, libsvnjavahl can be used, which depends on libsvn being installed and acts as a bridge between the language Java and libsvn, thus providing an API that invokes functions from libsvn to do the work. Major motives to create library bindings include

software reuse Code reuse is the practice of using existing source code to develop software instead of writing new code. ''Software reuse'' is a broader term that implies using any existing software asset to develop software instead of developing it again. An as ...

, to reduce reimplementing a library in several languages, and the difficulty of implementing some

algorithm In mathematics and computer science, an algorithm () is a finite sequence of Rigour#Mathematics, mathematically rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algo ...

s efficiently in some high-level languages.

Runtime environment

Object models

Common Object Request Broker Architecture The Common Object Request Broker Architecture (CORBA) is a standard defined by the Object Management Group (OMG) designed to facilitate the communication of systems that are deployed on diverse platforms. CORBA enables collaboration between sy ...

(CORBA) –

cross-platform Within computing, cross-platform software (also called multi-platform software, platform-agnostic software, or platform-independent software) is computer software that is designed to work in several Computing platform, computing platforms. Some ...

-language model *

Component Object Model Component Object Model (COM) is a binary-interface technology for software components from Microsoft that enables using objects in a language-neutral way between different programming languages, programming contexts, processes and machines ...

(COM) –

Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

only cross-language model **

Distributed Component Object Model Distributed Component Object Model (DCOM) is a proprietary Microsoft technology for communication between software components on networked computers. DCOM, which originally was called "Network OLE", extends Microsoft's COM, and provides the co ...

(DCOM) – extension enabling COM to work over networks ** Cross Platform Component Object Model (

XPCOM Cross Platform Component Object Model (XPCOM) is a cross-platform component model from Mozilla. It is similar to Component Object Model (COM), Common Object Request Broker Architecture (CORBA) and system object model (SOM). It features multiple ...

) – Mozilla applications

model *

Common Language Infrastructure 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/ ...

– .NET Framework

-language model *

Freedesktop.org freedesktop.org (fd.o), formerly X Desktop Group (XDG), is a project to work on interoperability and shared base technology for free-software desktop environments for the X Window System (X11) and Wayland on Linux and other Unix-like operatin ...

D-Bus D-Bus (short for "Desktop Bus") is a message-oriented middleware mechanism that allows communication between multiple Process (computing), processes running concurrently on the same machine. D-Bus was developed as part of the freedesktop.org pro ...

– open

-language model

Virtual machines

Comparison of application virtual machines Application virtualization software refers to both application virtual machines and software responsible for implementing them. Application virtual machines are typically used to allow application bytecode to run portably on many different comput ...

Porting

* Portable object –

-language object model definition

References

External links

JTC1/SC22/WG11 - Binding Techniques
an ISO standard for language bindings
What is a language binding?
Compilers Computer libraries {{compu-lang-stub