A number of Adobe applications support the Open Architecture (MOA). MOA provides a rich multimedia platform for both Adobe and third parties to build on to extend application functionality. The components of this architecture are described on in this document.

MOA is based on the Adobe Portable Object Model, which defines a way to declare interfaces that are implemented by classes. This model is compatible with the Component Object Model defined by Microsoft as the basis for OLE 2. In addition to the model, MOA provides a highly portable COM implementation that supports in-process objects on both the Macintosh and Windows.

MOA objects consist of 1) a set of private variables defined by a developer to keep track of relevant data, and 2) an implementation of one or more interfaces, each of which defines a table of virtual functions that provide the behaviors supported by the MOA object.

MOA objects are designed to be dynamically loaded into an application. They are the fundamental building blocks of Xtras, which contain functionality that can be plugged into Adobe applications. Application users simply drag Xtras into their application's Xtras folder to augment its functionality.

Adobe Xtras API enables developers to provide value-added extensions--Xtras--for many Adobe applications. The real breakthrough of this architecture is the development of Xtras that work not only across the Windows and Macintosh platforms with little or no platform-specific code, if no product specific interfaces are used, but will also work across multiple products (such as a Transition Xtra that works in both Director and Authorware). By having an architecture that is both cross-platform and cross-product, a third party creating an Xtra is assured of broader usage and bigger markets.

Xtras are the most visible and tangible result of the MOA for day-to-day users of Adobe products. Some Xtras are product-specific, while others are designed to work across multiple applications. The table below provides a sampling of how the Xtras can be supported in Adobe applications and where those Xtras appear in each application's user interface.

Connecting Xtras

The Adobe Xtras API supports rich, well-defined suites of functionality. One cornerstone of the architecture is the clear delineation of responsibilities between applications and Xtras. On the application side, this means providing a coherent way to expose internal data structures and behaviors to Xtras. On the Xtras side, this means providing modular units of behavior with the correct plugs to fit into corresponding application sockets. To support this, MOA uses interfaces- a standard means of defining the modules of functionality that an application or Xtra provides.

A second cornerstone is the provision of cross-application standards that define the interaction between applications and Xtras as generally as possible, to encourage developers to create Xtras that work across applications. For example, both Director and Authorware provide Xtras with access to the drawing surface of the display in precisely the same way.

All MOA-capable applications support a basic set of callback interfaces, which enable an Xtra to access standard services, including memory allocation, stream access, and simple user interface tools:

Similarly, all Xtras implement a set of cross-product interfaces so that they can register themselves and be installed into applications in a generic way.

Adobe Multimedia, Graphics, Audio

Functionality that is similar across applications is gathered into a common set of interfaces which can be accessed by Xtras, allowing a single Xtra to be used in multiple Adobe applications-even those released after an Xtra was created.

Multimedia Interfaces

Adobe defines a set of shared callback interfaces that are supported by Adobe multimedia applications. These interfaces are called by Xtras to invoke specific multimedia functionality inside an application (such as adding a new asset type to Director or Authorware). All applications that support multimedia implement these interfaces and can therefore share Xtras.

Adobe Apps

Adobe's core technologies provide the foundation for Adobe applications, forming the most extensive set of dynamic media building blocks in the industry. Adobe applications give Xtras access to these core technologies through product-specific interfaces for the internal data structures and major processing loops in those applications. This allows FreeHand Xtras to access splines, Director Xtras to access cast members, and SoundEdit Xtras to access sampled data streams.

Each application-specific Xtra provides an interface that can be called from its associated application, to provide information about the state of the Xtra processing and to provide appropriate information to the application display in dialogs or menus. Examples of product-specific interfaces include: