Events

An event is thrown by the VoiceXML platform for any type of reason, such as a user not responding to an input, not responding correctly, or requesting help, etc. An event is also thrown if there is a semantic error in the VoiceXML document, or when the <throw> element is encountered. The <throw> element generates an event (user-defined or system) and the <catch> element catches the event thrown by the VoiceXML document, dialog, or form item.

< throw >	The < throw > element generates predefined or user-defined events.

Following is an example of the use of the <throw> element:

<throw event="nomatch"/>

In this case, an event is generated when an input by the user is not recognized as part of the active grammar. The attribute for the <throw> element is event, which defines the event to be thrown.

< catch >	The <catch> element catches the event thrown by the VoiceXML document, dialog, or form item.

Folowing is an example of the use of the <catch> element:

<catch event="nomatch"/>
<throw event="event.password.invalid"/>
</catch>

Following is a set of available <catch> elements:

< error >	The < error > catch element catches events of type error.
< help >	The < help > catch element catches events if no help is available.
< noinput >	The < noinput > catch element catches events if there was no input by the user.
< nomatch >	The < nomatch > catches events if an input by the user is not recognized as part of the active grammar.