System Overview: Applications and Loadable Bundles

Applications and Loadable Bundles

Loadable bundles contain code and programming resources that an application can dynamically load at runtime. The most common type of loadable bundle is a plug-in, but there can be others, such as Interface Builder palettes. Loadable bundles are somewhat different from frameworks and can have a slightly different relation with applications.

Loadable bundles are bundles just as much as application packages. They can thus contain all the things an application can, such as private frameworks and other supplementary code, including other plug-ins and other loadable bundles. (Frameworks, on the other hand, are “versioned” bundles with a different internal organization, among other differences. See the chapter “Frameworks” for more information on frameworks.)

Plug-ins and other loadable modules are divided into three categories based on how essential they are to an application:

those that an application requires to run

those that are not essential to execution but that are considered part of an application because users generally want to use them (a tools palette, for example)

those that meet neither of the above criteria but offer some additional functionality (often provided by third-party developers)

Plug-ins and other loadable bundles that meet the first two criteria should be packaged in the PlugIns directory of the application bundle. They should always be packaged with the application so they come along if the user moves the application to another location. If a loadable bundle is in the third category, the convention for users is to install it in the

Library/Application
Support

directory of the logged-in user’s home directory (local or remote). System administrators or expert users can install such a loadable bundle in the

Library/Application
Support

directory of the system-local or network domains to make it more widely availabl e.

Regardless of where a plug-in or loadable module is stored, it is the responsibility of the application to provide some human-interface mechanism enabling users to select them (as files, not directories). As an example, an application might display a dialog listing all plug-ins available for loading.

Last updated: 2003-08-21




	Get information on Apple products. Visit the Apple Store online or at retail locations. 1-800-MY-APPLE Copyright © 2003 Apple Computer, Inc. All rights reserved. \| Terms of use \| Privacy Notice