Pat Deegan


        Copyright (C) 2007,2008 by Pat Deegan.
        All rights reserved

This library is released under the terms of the GNU GPL version 3, making it available only for free programs ("free" here being used in the sense of the GPL, see for more details). Anyone wishing to use this library within a proprietary or otherwise non-GPLed program MUST contact to acquire a distinct license for their application. This approach encourages the use of free software while allowing for proprietary solutions that support further development.

This file is part of VoiceXML::Client.

    VoiceXML::Client is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    VoiceXML::Client is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with VoiceXML::Client.  If not, see <>.


The VXML::Engine uses a number of components. These components serve to abstract away platform specific details, such as supported voice device hardware, TTS engines etc.

All components must use the VoiceXML::Client::Engine::Component as a base class (possibly indirectly, through multi-leveled inheritance). The VoiceXML::Client::Engine::Component serves as an abstract base class for all components, thereby assuring the engine that all it's components will provide a minimal common interface.

The VoiceXML::Client::Engine::Component class also implements the functionality that allows components to interact with other components, while using the engine as a mediator - thus eliminating any component interdependance (see the engineRequest() method); Components only know about the engine and the engine only guarantees that it will attempt to fullfill the request and will not die in the process.


Subclasses of Component may not use the reserved _component_ keyword as the first part of object hash keys (eg $self->{'_component_blah'}).


engineRequest TYPE [PARAM1 [PARAM2] [...]]

All components may request actions from the engine, using the engineRequest method. This method serves to mediate requests between components. For instance, a document fetcher may request the engine play background music while fetching a document, then request the engine stop playing music when done - all without the fetcher knowing anything about the audio components (Audio::Output and Audio::Device) involved in the activity.