ccxml elements - transition

CCXML 1.0-W3C Development Guide

<transition> element

The <transition> element is used to catch incoming asynchronous events. The first <transition> element encountered in the document order that matches up with a specific event will be the first one executed by the CCXML interpreter.

Once a <transition> has been encountered, the tags nested within the element will then be executed in document order. If an event is thrown, and no matching <transition> is exeistent in the document, then the event will be dropped entirely, (and there will consequently be a message in the Voxeo logger indicating that an unhandled event was encountered).

Should any subsequent events arrive while a <transition> is already in progress, this second event will be placed into the event queue for later processing.

usage

<transition cond="(ECMAScript Expression)" event="(ECMAScript Expression)" name="(variable name)" state="STRING">

attributes

cond	Data Type: (ECMAScript Expression)	Default: True
	The cond attribute specifies an ECMAScript expression which can be evaluated to 'true' or 'false'. A condition must evaluate to 'true' in order for any enclosed operations to be performed.
event	Data Type: (ECMAScript Expression)	Default: none - attribute is required
	The event attribute denotes the matching event type used to kick off the code contained within the <transition> element. Event types can be a user-defined, dot separated ECMAScript string of any length, or, (more commonly), it can indicate a platform-defined event type. Note that the '*' suffix is a wildcard, and will match zero or more characters of any event name.
name	Data Type: (variable name)	Default: none - attribute is required
	The name attribute denotes the unique variable that is to receive the event indicated in the <transition> element.
state	Data Type: STRING	Default: none - attribute is required
	Indicates the current possible state(s) of the eventhandler.

parents

<eventprocessor>

children

<accept> <assign> <createccxml> <createconference> <destroyconference> <dialogstart> <dialogterminate> <disconnect> <else> <elseif> <if> <join> <reject> <send> <unjoin> <var>

code samples

<1.0 transition>

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns="http://www.w3.org/2002/09/ccxml">

<meta name="author" content="Jeff Menkel"/>
<meta name="copyright" content="2007 Voxeo Corporation"/>
<meta name="maintainer" content="YOUR_EMAIL@HERE.COM"/>

<eventprocessor>

<transition event="connection.alerting">
<log expr="'*** Incoming call detected ***'"/>
<accept/>
</transition>

<transition event="connection.connected">
<log expr="'*** The call was answered ***'"/>
<disconnect/>
</transition>

<transition event="connection.disconnected">
<log expr="'*** Disconnecting ***'"/>
<exit/>
</transition>

</eventprocessor>
</ccxml>

additional links

W3C Specification

ANNOTATIONS: EXISTING POSTS

mtatum111

10/9/2008 3:36 PM (EDT)

can you explain the difference between the event attribute and the name attribute for <transition>

It appears that both of them are very similar.

Thanks

voxeoAlexBring

10/9/2008 4:49 PM (EDT)

Hey Melissa,
The name attribute is actually now an outdated part of the transition element. It has been replaced by a much better feature that is built into ccxml 1.0-W3C. The newer feature is "event$". For example using it would look like this:
instead of:
[color=red]
<transition event="connection.connected" name="evnt">
<assign name="conn_id" expr="evnt.connectionid"/>
</transition>
[/color]
it would look like this:
[color=red]
<transition event="connection.connected">
<assign name="conn_id" expr="event$.connectionid"/>
</transition>
[/color]
Hope this helps to clear up any confusion, if you have any other questions please don't hesitate to ask.

Standing by,
Alex