ActiveX is a framework for defining reusable software components in a programming language-independent way. Software applications can then be composed from one or more of these components in order to provide their functionality.[1]
It was introduced in 1996 by Microsoft as a development of its Component Object Model (COM) and Object Linking and Embedding (OLE) technologies and is commonly used in its Windows operating system, although the technology itself is not tied to it.
Many Microsoft Windows applications — including many of those from Microsoft itself, such as Internet Explorer, Microsoft Office, Microsoft Visual Studio, and Windows Media Player — use ActiveX controls to build their feature-set and also encapsulate their own functionality as ActiveX controls which can then be embedded into other applications. Internet Explorer also allows embedding ActiveX controls onto web pages.
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ActiveX controls, mini program building blocks, can serve to create distributed applications working over the Internet through web browsers. Examples include customized applications for gathering data, viewing certain kinds of files, and displaying animation.
ActiveX controls are comparable to Java applets: programmers designed both of these mechanisms to allow web browsers to download and execute them. But Java applets can run on nearly any platform, while ActiveX components officially operate only with Microsoft's Internet Explorer web browser and the Microsoft Windows operating system.[2]
Malwares, e.g. computer viruses and spywares, can be accidentally installed from malicious websites using ActiveX controls (drive-by downloads).
Programmers can write ActiveX controls in any language which supports COM component development, including the following languages/environments:
Common examples of ActiveX controls include command buttons, list boxes, dialog boxes, and the Internet Explorer browser.
Faced with the complexity of OLE 2.0 and with poor support for COM in MFC, Microsoft rationalized the specifications to make them simpler, and rebranded the technology as ActiveX in 1996.[4][5] Even after simplification, users still required controls to implement about six core interfaces. In response to this complexity, Microsoft produced wizards, ATL base classes, macros and C++ language extensions to make it simpler to write controls.
Starting with Internet Explorer 3.0 (1996), Microsoft added support to host ActiveX controls within HTML content. If the browser encountered a page specifying an ActiveX control via an OBJECT tag, it would automatically download and install the control with little or no user intervention. This made the web "richer" but provoked objections (since such controls ran only on Windows) and security risks (especially given the lack of user intervention). Microsoft subsequently introduced security measures to make browsing including ActiveX safer[6] . For example:
It may not always be possible to use Internet Explorer to execute ActiveX content (e.g. on a Wine installation), nor may a user want to.
Microsoft has developed a large number of products and software platforms using ActiveX objects. Some remain in use as of 2009:
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