Component-based software engineering (CBSE), also called component-based development (CBD), is a style of software engineering that aims to build software out of loosely-coupled, modular components. It emphasizes the separation of concerns among different parts of a software system.
An individual software component is a software package, web service, web resource, or module that encapsulates a set of related functions or data.
Components communicate with each other via interfaces . Each component provides an interface (called a provided interface) through which other components can use it. When a component uses another component's interface, that interface is called a used interface.
In the UML illustrations in this article, provided interfaces are represented by lollipop-symbols, while used interfaces are represented by open socket symbols.
Components must be substitutable, meaning that a component must be replaceable by another one having the same interfaces without breaking the rest of the system.
Components should be reusable.
Component-based usability testing should be considered when software components directly interact with users.
Components should be:
The idea that software should be componentized, or built from prefabricated components, first became prominent with Douglas McIlroy's address at the NATO conference on software engineering in Garmisch, Germany, 1968, titled Mass Produced Software Components. [1] The conference set out to counter the so-called software crisis. McIlroy's subsequent inclusion of pipes and filters into the Unix operating system was the first implementation of an infrastructure for this idea.
Brad Cox of Stepstone largely defined the modern concept of a software component. [2] He called them Software ICs and set out to create an infrastructure and market for these components by inventing the Objective-C programming language. (He summarizes this view in his 1986 book, Object-Oriented Programming - An Evolutionary Approach.)
Software components are used in two different contexts: i) using components as parts to build a single executable, or ii) each executable is treated as a component in a distributed environment, where components collaborate with each other using internet or intranet communication protocols for IPC (Inter Process Communications). The above belongs to the former kind, while the below belongs to the latter kind.
IBM led the path with their System Object Model (SOM) in the early 1990s. As a reaction, Microsoft paved the way for actual deployment of component software with Object linking and embedding (OLE) and Component Object Model (COM). [3] As of 2010 [update] many successful software component models exist.
A computer running several software components is often called an application server. This combination of application servers and software components is usually called distributed computing. Typical real-world applications of this include financial applications and business software.
A component model is a specification of components' properties. [4]
A classification of the existing component models is given in [4] and. [5] Examples of component models are: Enterprise JavaBeans (EJB) model, Component Object Model (COM) model, .NET model, X-MAN component model, [6] and Common Object Request Broker Architecture (CORBA) component model.
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System.ComponentModel namespace in Microsoft .NET In distributed computing, a Remote Procedure Call (RPC) is when a computer program causes a procedure (subroutine) to execute in a different address space, which is written as if it were a normal (local) procedure call, without the programmer explicitly writing the details for the remote interaction. That is, the programmer writes essentially the same code whether the subroutine is local to the executing program, or remote. This is a form of client–server interaction, typically implemented via a request–response message passing system. In the object-oriented programming paradigm, RPCs are represented by remote method invocation (RMI). The RPC model implies a level of location transparency, namely that calling procedures are largely the same whether they are local or remote, but usually, they are not identical, so local calls can be distinguished from remote calls. Remote calls are usually orders of magnitude slower and less reliable than local calls, so distinguishing them is important.
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 systems on different operating systems, programming languages, and computing hardware. CORBA uses an object-oriented model although the systems that use the CORBA do not have to be object-oriented. CORBA is an example of the distributed object paradigm.
OpenStep is an object-oriented application programming interface (API) specification developed by NeXT. It provides a framework for building graphical user interfaces (GUIs) and developing software applications. OpenStep was designed to be platform-independent, allowing developers to write code that could run on multiple operating systems, including NeXTSTEP, Windows NT, and various Unix-based systems. It has influenced the development of other GUI frameworks, such as Cocoa for macOS, and GNUstep.
Middleware in the context of distributed applications is software that provides services beyond those provided by the operating system to enable the various components of a distributed system to communicate and manage data. Middleware supports and simplifies complex distributed applications. It includes web servers, application servers, messaging and similar tools that support application development and delivery. Middleware is especially integral to modern information technology based on XML, SOAP, Web services, and service-oriented architecture.
ActiveX is a deprecated software framework created by Microsoft that adapts its earlier Component Object Model (COM) and Object Linking and Embedding (OLE) technologies for content downloaded from a network, particularly from the World Wide Web. Microsoft introduced ActiveX in 1996. In principle, ActiveX is not dependent on Microsoft Windows operating systems, but in practice, most ActiveX controls only run on Windows. Most also require the client to be running on an x86-based computer because ActiveX controls contain compiled code.
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 types and interfaces in a language-independent way, for example, between those written in C++ and those written in Java.
In computer science, an object can be a variable, a data structure, a function, or a method. As regions of memory, objects contain a value and are referenced by identifiers.
An object-oriented operating system is an operating system that is designed, structured, and operated using object-oriented programming principles.
In distributed computing, an object request broker (ORB) is a concept of a middleware, which allows program calls to be made from one computer to another via a computer network, providing location transparency through remote procedure calls. ORBs promote interoperability of distributed object systems, enabling such systems to be built by piecing together objects from different vendors, while different parts communicate with each other via the ORB. Common Object Request Broker Architecture standardizes the way ORB may be implemented.
In software engineering, service-oriented architecture (SOA) is an architectural style that focuses on discrete services instead of a monolithic design. By consequence, it is also applied in the field of software design where services are provided to the other components by application components, through a communication protocol over a network. A service is a discrete unit of functionality that can be accessed remotely and acted upon and updated independently, such as retrieving a credit card statement online. SOA is also intended to be independent of vendors, products and technologies.
In programming and software design, binding is an application programming interface (API) that provides glue code specifically made to allow a programming language to use a foreign library or operating system service.
.NET Remoting is a Microsoft application programming interface (API) for interprocess communication released in 2002 with the 1.0 version of .NET Framework. It is one in a series of Microsoft technologies that began in 1990 with the first version of Object Linking and Embedding (OLE) for 16-bit Windows. Intermediate steps in the development of these technologies were Component Object Model (COM) released in 1993 and updated in 1995 as COM-95, Distributed Component Object Model (DCOM), released in 1997, and COM+ with its Microsoft Transaction Server (MTS), released in 2000. It is now superseded by Windows Communication Foundation (WCF), which is part of the .NET Framework 3.0.
Apache Axis2 is a web service engine. It is a redesign and re-write of the widely used Apache Axis SOAP stack. Implementations of Axis2 are available in Java and C.
Component Object Model (COM) is a binary-interface standard for software components introduced by Microsoft in 1993. It is used to enable inter-process communication (IPC) object creation in a large range of programming languages. COM is the basis for several other Microsoft technologies and frameworks, including OLE, OLE Automation, Browser Helper Object, ActiveX, COM+, DCOM, the Windows shell, DirectX, UMDF and Windows Runtime.
Robotics middleware is middleware to be used in complex robot control software systems.
An application programming interface (API) is a way for two or more computer programs or components 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 to build or use such a connection or interface is called an API specification. A computer system that meets this standard is said to implement or expose an API. The term API may refer either to the specification or to the implementation. Whereas a system's user interface dictates how its end-users interact with the system in question, its API dictates how to write code that takes advantage of that system's capabilities.
An Internet operating system, or Internet OS, is any type of operating system designed to run all of its applications and services through an Internet client, generally a web browser. The advantages of such an OS would be that it would run on a thin client, allowing cheaper, more easily manageable computer systems; it would require all applications to be designed on cross-platform, open standards; and would not tie a user's applications, documents, and preferences to a single computer, but rather place them in the Internet cloud. The Internet OS has also been promoted as the perfect type of platform for software as a service.
Middleware is a type of computer software program that provides services to software applications beyond those available from the operating system. It can be described as "software glue".
The modern concept of a software component largely defined by Brad Cox of Stepstone, => Objective-C programming language
1990, IBM invents their System Object Model. 1990, as a reaction, Microsoft released OLE 1.0 OLE custom controls (OCX)[ permanent dead link ]
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