Advanced Common Application Platform - The Role of ACAP

The Role of ACAP

In essence, ACAP makes it appear to interactive programming content that it is running on a so-called "common receiver." This common receiver contains a well-defined architecture, execution model, syntax and semantics.

As a middleware specification for interactive applications, ACAP gives content and application authors assurance that their programs and data will be received and run uniformly on all brands and models of receivers.

Trial implementations have already been done in South Korea by a consortium of organizations. In addition, an extensive ACAP demonstration was held at NAB2004.

An ACAP application is a collection of information processed by an application environment to interact with an end-user or otherwise alter the stateof- the-application environment. ACAP applications are classified into two categories, depending on whether the initial application content processed is of a procedural or a declarative nature.

These categories of applications are referred to as procedural (ACAP-J) and declarative (ACAP-X), respectively. An example of an ACAP-J application is a Java TV Xlet composed of compiled Java byte codes in conjunction with other multimedia content such as graphics, video and audio. An example of an ACAP-X application is a multimedia document composed of XHTML markup, style rules, scripts and embedded graphics, video and audio.

An ACAP application need not be purely procedural or declarative. In particular, an ACAP-J application may reference declarative content, such as graphics, or may construct and cause the presentation of markup content.

Similarly, ACAP-X applications may use script content, which is procedural in nature. Furthermore, an ACAP-X application may reference an embedded Java TV Xlet.

The architecture and facilities of ACAP are intended to apply to broadcast systems and receivers for terrestrial broadcast and cable TV systems.

In addition, the same architecture and facilities may be applied to other transport systems, such as satellite. ACAP is primarily based on the GEM (Globally Executable Multimedia) home platform specification developed by the DVB consortium and DASE, developed by the ATSC.