What are PlugIns?

PlugIns

What are plugins?
     A plugin is a piece of software that extends the basic capability of a browser. Often plugins allow for better video or audio support. In Nasdaq Online, the Shockwave plugin is used to enhance the appearance and operation of the control buttons used throughout the system.
     Plugin modules are software programs that extend the capabilities of browsers. A plugin is installed on your hard disk using instructions that come with the plugin.
     The plugin application programming interface (API) allows third parties to extend browsers with native support for new data types and additional features. Plugins are dynamic code modules, native to each browser platform. Plug-ins are complementary to architectures such as OLE and platform-independent programming languages such as Java. Here are the primary goals of the plugin API:

Provide seamless new data-type support for browser users.
Provide the maximum degree of flexibility for plugin writers.
Be functionally equivalent across all platforms.

The plug-in API supports four broad areas of functionality. Plugins can:

Draw into, and receive events from, a native window element that is a part of the browsers window hierarchy.
Obtain data from the network via URLs.
Generate data for consumption by other plug-ins or browsers.

     Plug-ins can have one of three modes of operation: embedded, full-screen, or hidden. An embedded plugin is a part of a larger HTML document, visible as a rectangular frame within a page (embedded plug-ins are specified in HTML with the EMBED tag). A full-screen plug-in is a self-contained viewer, completely filling the content area of a browser window. A hidden plug-in runs in the background.
     The browsers user interface remains relatively unchanged even when plug-ins are in use. Frames without plug-in data function like ordinary frames. Basic operations such as navigation, history, and opening files are not changed by plugins.
     A plugin can retrieve a URL with the same network functionality as a browser. The data from such a URL is provided as a stream as the data arrives from the network. Plug-ins can themselves generate data that browsers or other plug-ins can display. Plugins can both produce and consume data.
     Plugins are associated with a MIME data type that the browser does not natively support. When a browser encounters an unknown data type from a server, the browser looks for a plug-in that is associated with that MIME type and loads the plug-in.

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