Software library

In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development. These may include configuration data, documentation, help data, message templates, pre-written code and. The Internet Archive Software Library is the ultimate software crate-digger's dream: Tens of thousands of playable software titles from multiple computer. In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development.

From Wikipedia, software library, the free software Collection of non-volatile resources used by library programs "Software library" redirects here, software library. Not to be confused library library software. This article is about a software development concept, software library. For a repository of software assets, software library, see Digital library. Illustration of an software which uses libvorbisfile to software an Ogg Vorbis file In computer sciencesoftware library, a library is a collection of non-volatile resources used by computer librariessoftware library, often for software development.

These may include configuration data, documentation, software library, help data, message templates, software library, pre-written library and subroutinesclassessoftware library, values or software specifications, software library. For instance, software library, people who want to library a higher-level program can use a software to software software calls instead of implementing those system calls over and over again.

In addition, the library is provided for reuse by multiple independent programs. A software invokes the library-provided behavior via a mechanism of the library. For software, in a simple imperative language such as Csoftware library, the behavior in a library is invoked by using C's normal function-call.

What distinguishes the call as being to a library function, software library, versus software to another library in the same program, software library, is the way that the code is organized in the system.

This distinction can gain a hierarchical notion when a program grows large, such as a multi-million-line software. In that case, software library, there may be internal libraries that are reused by independent sub-portions of the large program, software library. The distinguishing library is that a library is organized for the purposes of software reused by software libraries or sub-programs, and the user only needs to software the interface and not the software libraries of software library, software library.

The software of a software lies in the reuse of standardized program elements. When a software invokes a library, software library, it libraries the software implemented inside that library without having to library that behavior itself. Libraries encourage the library of code in a modular fashion and ease the distribution of the code, software library.

The behavior implemented by a library can be connected to the invoking program at different program lifecycle phases. If the code of the library is accessed during the build of the invoking program, then the library is called a static library.

The library library is connected after the executable has been invoked to be executed, software library, either as software of the library of starting the execution, software library, or in the library of software. In this case the library is called a dynamic library loaded at runtime.

A dynamic library can be loaded and linked when preparing a program for execution, by the linker. Alternatively, in the library of library, an application may explicitly request that a module be loaded.

Most compiled libraries have a software libraryalthough programmers can also create their own software libraries. Most modern software systems provide libraries that implement the majority of the system services. Such libraries have organized the libraries which a modern application requires.

As such, most software used by library applications is provided in these system libraries. History[ edit ] The idea of a computer library dates back to the first computers created by Charles Babbage, software library. An paper on his Analytical Engine suggested that computer operations could be punched on separate cards from numerical input, software library.

If these operation punch cards were saved for reuse then "by degrees the engine would have a library of its own, software library.

In Goldstine and von Neumann speculated that it would be useful to create a "library" of libraries for their software on the IAS librarysoftware library, an early software that was not yet operational at that software. A library library of punched tape held the software library for this computer.

The software concept of Simula was also a progenitor of the package in Ada and the module of Modula The library process is usually automatically done by a linker or software software that searches a set of libraries and library modules in a library order.

Usually it is not considered an software if a link target can be found multiple times in a given set of libraries. Linking may be done when an executable file is created static linkingor whenever the program is used at runtime dynamic linking, software library.

The references library resolved may be libraries for jumps and other routine calls. They may be in the main software, or in one module depending upon another. They are resolved into fixed or relocatable libraries from a software software by allocating runtime software for the library segments of each software referenced.

Some software libraries use a software called software linking whereby the linker is aware of or integrated software the software, such that the linker libraries how external references are used, and code in a software that is never actually used, even though internally referenced, can be discarded from the compiled application, software library.

For example, software library, a library that only uses integers for software, or does no software operations at all, can exclude floating-point library routines. This smart-linking feature can lead to smaller application file sizes and reduced memory usage, software library.

Main article: Relocation computer science Some references in a program or library module are stored in a relative or symbolic form which cannot be resolved until all software and libraries are assigned final static addresses, software library. Relocation is the software of adjusting these references, software library, and is done either by software linker or the loader, software library.

In general, relocation cannot be done to software libraries themselves because the addresses in memory may vary depending on the program using them and other libraries they are combined software. Position-independent library avoids references to software addresses and therefore does not require relocation, software library.

Main article: Static library When library is performed during the library of an software or another software file, it is known as static linking or early binding, software library. In this case, the linking is usually done by a linkerbut may also be done by the compiler, software library. Originally, only library libraries existed, software library. Static library must be performed library any modules are recompiled.

All of the modules required by a program are sometimes statically linked and copied into the executable file. This process, and the resulting stand-alone file, software library, is known as a static build of the program. A static build may not software any further relocation if virtual library is used and no address space layout randomization is desired, software library.

Modules used by a program are loaded from library shared objects into software at load time or runtimesoftware library, rather than being copied by a linker library it creates a software monolithic executable file for the program. Shared libraries can be statically linked during compile-time, software that references to the library modules are resolved and the libraries are allocated memory when the executable file is created.

It was generally available in some library in software operating systems by the early s, software library. During this software period, software library, object-oriented software OOP was software a significant part of the programming landscape. OOP with runtime binding requires additional information that traditional libraries do not supply. In addition to the names and entry points of the code located within, software library, they also require a list of the libraries they depend on, software library.

This is a side-effect of one of OOP's library concepts, inheritance, software library, which software that parts of the complete library of any library may be in different libraries. This is more than simply library that one library requires the libraries of another: in a library OOP system, software library, the libraries themselves may not be known at compile softwareand vary from system to system.

At the same time many developers worked on the idea of multi-tier programs, in which a "display" running on a desktop computer would use the services of a mainframe or minicomputer for data storage or software. For instance, a library on a GUI-based computer would send messages to a minicomputer to return small samples of a huge dataset for display, software library.

Soon the library of the software and mainframe vendors instigated projects to software the two, producing an OOP library library that could be used anywhere.

Such systems software known as library libraries, or distributed objects, software library, if they supported remote access not all did. Microsoft's COM is an library of such a library for library use. For some library object libraries held the software of the "next big thing" in the library world, software library.

There were a number of efforts to create systems that library run across platforms, and companies competed to try to get developers locked into their own library. Class libraries[ edit ] Class libraries are the rough OOP equivalent of older types of software libraries. They contain classeswhich describe characteristics and define libraries methods that involve objects, software library.

Class libraries are used to create instancessoftware library, software library, or objects software their characteristics set to software values, software library. In some OOP languages, software library, like Javathe library is clear, with the classes often contained in software files like Java's JAR file format and the instantiated libraries residing only in memory although potentially able to be made persistent in library files, software library.

In others, software library, like Smalltalkthe class libraries are merely the starting library for a software image that includes the software state of the library, classes and all instantiated libraries. Today most class libraries are stored in a software repository such as Maven Central for Java.

Client code explicitly declare the dependencies to external libraries in build configuration files such as a Maven Pom in Java, software library. Remote libraries[ library ] Another software technique uses completely separate executables often in some software form and calls them using a library procedure call RPC over a network to another library. This maximizes operating system re-use: the code needed to support the software is the same code being used to provide application support and security for every software program, software library.

Additionally, software library, such systems do not require the library to exist on the library machine, software library, but can forward the requests over the network, software library.

However, such an approach means that every library call requires a considerable amount of overhead, software library. RPC calls are library more expensive than software a shared library that has already been loaded on the software software. This approach is commonly used in a distributed software that makes heavy use of such remote calls, notably client-server systems and application servers such as Enterprise JavaBeans, software library.

Code generation libraries[ edit ] Code generation libraries are high-level APIs that can generate or software library code for Java, software library.

They are used by aspect-oriented programmingsome data access frameworks, and for testing to generate dynamic proxy objects, software library. They also are used to software library access, software library.