ActiveX
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ActiveX is a framework for defining reusable software components (known as controls) that perform a particular function or a set of functions in a way that is independent of the programming language used to implement them. A software application can then be composed from one or more of these components in order to provide its functionality.[1]
It was introduced in 1996 by Microsoft Corporation as a development of its Component Object Model (COM) and Object Linking and Embedding (OLE) technologies and it 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 Corporation itself, such as Internet Explorer, Microsoft Office, Microsoft Visual Studio, Windows Media Player, etc. — 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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[edit] ActiveX controls
ActiveX controls — small program building blocks — can serve to create distributed applications that work over the Internet through web browsers. Examples include customized applications for gathering data, viewing certain kinds of files, and displaying animation.
One can compare ActiveX controls in some sense to Java applets: programmers designed both these mechanisms so that web browsers could download and execute them. However, they also differ:
- 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]
- Programmers can grant to ActiveX controls a much higher level of control over Windows than Java applets ever achieve, making them both more powerful and dangerous. Malware, such as computer viruses and spyware, often spreads as ActiveX controls in webpages.
Programmers can write ActiveX controls in any of the following languages/environments:
Common examples of ActiveX controls include command buttons, list boxes, dialog boxes, and the Internet Explorer browser.
[edit] History
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.[3][4] 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 only ran on Windows) and security risks (especially given the lack of user intervention). Microsoft subsequently introduced security measures to make browsing including ActiveX safer. For example:
- digital signing of installation packages (Cabinet files and executables)
- controls must explicitly declare themselves safe for scripting
- increasingly more stringent default security settings
- Internet Explorer maintains a blacklist of bad controls
[edit] Other ActiveX technologies
Microsoft has developed a large number of products and software platforms using ActiveX objects, and[weasel words]many remain in use as of 2009:
- ActiveX Data Objects (ADO)
- Active Server Pages
- ActiveMovie, later renamed to DirectShow
- Active Messaging, later renamed to Collaboration Data Objects
- Active Scripting, a technology for scripting ActiveX objects
- ActiveX Streaming Format (ASF), renamed to Advanced Streaming Format, then to Advanced Systems Format
[edit] Active technologies
In the late 1990s Microsoft began to reuse the term "Active" in a large number of its technologies. The following technologies do not relate to ActiveX itself, but have similar naming:
[edit] See also
- Active Setup
- Active Template Library
- IUnknown interface
- Windows DNA
- NPAPI, an alternative interface for web-browser plugins
[edit] Notes
- ^ Introduction to ActiveX Controls at microsoft.com, accessed 18-Jan-2008
- ^ "ActiveX". Mozilla. 2009-02-24. http://support.mozilla.com/en-US/kb/Activex. Retrieved on 2009-03-12. "As a Microsoft product, ActiveX was specifically designed to work with Windows systems. ActiveX is not supported by Microsoft on other operating systems such as Mac or Linux."
- ^ "Using ActiveX with LabVIEW -- Examining Mission Editor Version 1.0". NI Developer Zone. National Instruments. 2007-08-13. http://zone.ni.com/devzone/cda/tut/p/id/4496. Retrieved on 2009-03-12. "The term ActiveX surfaced in the Microsoft world in early 1996."
- ^ "Microsoft Announces ActiveX Technologies: Microsoft Corp. announced ActiveX Technologies, which make it easy for the broadest range of software developers and Web designers to build dynamic content for the Internet and the PC.". Microsoft PressPass. Microsoft. 1996-03-12. http://www.microsoft.com/presspass/press/1996/mar96/activxpr.mspx. Retrieved on 2009-03-12. "SAN FRANCISCO, March 12, 1996 - Microsoft Corp. today announced ActiveX ... Technologies, which make it easy for the broadest range of software developers and Web designers to build dynamic content for the Internet and the PC. ... ActiveX Technologies form a robust framework for creating interactive content using software components, scripts and existing applications. Specifically, ActiveX Technologies enable developers to build Web content easily using ActiveX Controls (formerly OLE Controls), active scripts and active documents. ... ActiveX Technologies are available in the form of the Microsoft ActiveX Development Kit, which is being distributed to more than 4,000 developers attending the Professional Developers Conference in San Francisco today."
[edit] External links
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