2.1. The Unified API

The Unified API (Application Programming Interface) enables the development of applications across a variety of manufacturers switches (both Key and PBX systems) through a single interface. The Unified API provides a single set of basic functions (refer to Chapter 3) that can be used for any supported switch and are sent directly to the switch through the D/42 Series board, without additional hardware. Functioning as an extension to Dialogic standard voice API, the Unified API offers a single design model that allows developers to take advantage of advanced PBX features (such as called/calling number ID and ASCII display information).

Using the Unified API shortens development time by eliminating the need to learn separate APIs for each switch. It enables you to create applications with a common set of functions, which operate with switches produced by different manufacturers, thereby widening your product's support beyond the traditional single-switch focus.

Developers who wish to continue designing switch-specific applications can continue to do so, as the Unified API also provides access to lower-level function calls made available through each individual switch protocol. And for customers unwilling to shift from older PBX integration development models, the Unified API provides for backward compatibility, preserving their development investment.

Utility functions included in the Unified API allow programmers to control the D/42 Series board. The application can retrieve the D/42-xx channel type, obtain and set D/42-xx channel parameters, start and stop the D/42 driver, and retrieve D/42 firmware/driver/library version numbers. The application can retrieve error information using the ATDV_LASTERR( ) and ATDV_ERRMSGP( ) functions in the standard voice API.

The D/42 runtime library works in conjunction with the standard voice runtime library to enable applications to set up calls and perform PBX call functions using D/42-xx boards. In addition, the D/42 runtime library supports the Unified API.

NOTE:

The Unified API contains both synchronous and asynchronous functions. These terms, along with programming models and callback handlers or asynchronous event handlers, are discussed in the Standard Runtime Library Programmer's Guide, which is in the Voice Software Reference.

The D/42 runtime library treats boards and channels as separate devices, even though channels are physically part of a board. A channel device is an individual PBX line connection, and a board device is a D/42-xx board that contains channels. Most functions are performed at the channel level, such as getting called/calling number ID. Certain functions, such as setting board parameters, can occur at the board level and effect all channels on that board.

NOTE:

Since boards and channels are considered separate devices under Windows, it is possible to open and use a channel without opening the board where the channel is located. There is no board-channel hierarchy imposed by the D/42 runtime library.

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