<data>

Experimental Extension. Fetches arbitrary XML data from an HTTP server, or submits values to a server.

Syntax

 <data
     src="URI"
     name="string"
     srcexpr="js_expression"
     expr="js_expression"
     method="get"|"post"
     namelist="variable1 ..."
     enctype=MIME_type
     fetchhint="prefetch"|"safe"
     fetchtimeout="time_interval"
     fetchaudio="URI" 
     maxage="time_interval" 
     maxstale="time_interval" 
 />

Description

The <data> tag fetches or submits data without transitioning to a new VoiceXML document.

The XML data fetched by the <data> element is returned in a read-only JavaScript variable via an object model as specified in the W3C Document Object Model (DOM), described in http://www.w3c.org/TR/DOM-Level-2-Core. Appendix E of the specification describes the JavaScript language binding for the DOM.

Note: The current BeVocal VoiceXML implementation of <data> precedes finalization of the standard to give developers the opportunity to use the tag and provide feedback, which we can pass on to the W3C. If <data> is standardized, the BeVocal VoiceXML implementation will change as necessary to match the VoiceXML standard. If such changes occur, we will attempt to maintain backwards compatibility with the current implementation.

Attribute Description

src
URI specifying the location of the XML data. Optional (as alternative to expr).

name
Variable name, which must be a valid JavaScript identifier and may not be a reserved keyword in either JavaScript or Java.

If the name attribute is omitted, the HTTP request is submitted, but the retrieved data is ignored.

srcexpr
JavaScript expression that evaluates to grammar file URI. Optional (as alternative to src or an inline grammar).

If you specify this attribute, the element cannot have content.

You can specify either srcexpr or expr, but not both. If you specify both, a parse error is thrown.

expr
Extension. JavaScript expression that evaluates to grammar file URI. Optional (as alternative to src or an inline grammar).

Note: The expr attribute has been replaced by the srcexpr attribute and may be deprecated in a future release.

If you specify this attribute, the element cannot have content.

You can specify either srcexpr or expr, but not both. If you specify both, a parse error is thrown.

method
The query request method, either get or post. Optional (default is get).

enctype
MIME encoding used when submitting data with the post method. Optional (default is application/x-www-form-urlencoded).

The supported types are:
application/x-www-form-urlencoded multipart/form-data
The type multipart/form-data is more efficient when submitting large amounts of binary data.

namelist
Space-separated list of variables to submit to the server. Optional (default is to submit no variables).

This attribute can specify any variable currently in scope, both VoiceXML variables and JavaScript variables, including shadow variables and other variables that have not been explicitly declared.

A variable set to a JavaScript object is submitted as the individual component values; see Submitting Complex JavaScript Objects.

fetchhint
Specifies whether the interpreter can attempt to optimize dialog interpretation by prefetching the resource. See Prefetching Resources. Optional.

fetchtimeout
Specifies the interval to wait for the resource to be returned before throwing a error.badfetch event. See Handling Fetching Delays. Optional.

fetchaudio
Specifies the URI of an audio clip to play while a resource is being fetched. See Background Audio. Optional.

The specified audio clip is played only if the bevocal.dtmf.flushbuffer property is set to true.

maxage
Specifies the maximum acceptable age, in seconds, of the cached resource. See Maximum Age. Optional.

maxstale
Specifies the maximum acceptable time, in seconds, during which an expired cached resource can still be used. See Maximum Stale Time. Optional.

If a <data> element names a variable that is already in scope, it does not declare a new variable with the same name, but simply assigns a value to the existing variable--the variable is assigned a reference to the DOM returned from the server.

(VoiceXML 1.0 only) The following attributes can be used in applications in which the version attribute of the <vxml> tag is set to 1.0.

Attribute Description

caching
VoiceXML 1.0 only. Specifies the caching policy for the resource being fetched. See Caching. Optional.

Used in place of the VoiceXML 2.0 attributes maxage and maxstale.

Tip:

•	If a JavaScript expression contains any of the characters "`<`", "`>`", or "`&`", that character must be replaced with the corresponding escape sequence "`<`", "`>`", or "`&`". For more information, see JavaScript Quick Reference.

Usage

Parents Children

<bevocal:foreach> <block> <catch> <error> <filled> <foreach> <form> <help> <if> <noinput> <nomatch> <vxml>
None.

See Also

None

Example

 <?xml version="1.0" ?>
 <!DOCTYPE vxml PUBLIC "-//BeVocal Inc//VoiceXML 2.0//EN"
  "http://cafe.bevocal.com/libraries/dtd/vxml2-0-bevocal.dtd">
 
 <vxml version="2.0" xmlns="http://www.w3.org/2001/vxml">
   <var name="quote"/>
   <var name="ticker" expr="'f'"/>
 
   <form id="get_quote">
     <block>
       <data name="quote" src="quote.xml"/>
       <assign name="document.quote" expr="quote.documentElement"/>
       <goto next="#play_quote"/>
     </block>
   </form>
 
   <form id="play_quote">
     <script>
       <![CDATA[
         // retrieve the value contained in the node t from the DOM exposed by d
         function GetData(d, t, nodata) {
           try {
             return d.getElementsByTagName(t).item(0).firstChild.data;
           }
           catch(e) {
             // the value could not be retrieved, so return this instead
             return nodata;
           }
         }
       ]]>
     </script>
 
     <block>
       <!-- retrieve the change in the stock's value -->
       <var name="change" expr="GetData(quote, 'change', 0)"/>
 
       <!--Say the company name -->
       <prompt>
         The stock for <value expr="GetData(quote, 'name', 'unknown')"/> is
       </prompt>
       <!-- Say 'unchanged, 'up', or 'down' -->
       <!-- based on zero, positive, or negative change -->
       <if cond="change == 0">
         <prompt> unchanged at </prompt>
       <else/>
         <if cond="change &gt; 0"> <!-- Positive change -->
           <prompt> up by </prompt>
         <else/> <!-- Negative change -->
           <prompt> down by </prompt>
         </if>
 
         <!-- Say change in value as positive number -->
         <prompt>
           <value expr="Math.abs(change)"/> to
         </prompt>
       </if>
       <!-- Say the current price per share -->
       <prompt> <value expr="GetData(quote, 'last', 0)"/> </prompt>
     </block>
   </form>
 </vxml>

The data file quote.xml follows:

 <?xml version="1.0" ?>
 <xml>
   <quote>
     <ticker>F</ticker>
     <name>Ford Motor Company</name>
     <change>1.0</change>
     <last>30.00</last>
   </quote>
 </xml>

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Attribute	Description
`src`	URI specifying the location of the XML data. Optional (as alternative to `expr`).
`name`	Variable name, which must be a valid JavaScript identifier and may not be a reserved keyword in either JavaScript or Java. If the `name` attribute is omitted, the HTTP request is submitted, but the retrieved data is ignored.
`srcexpr`	JavaScript expression that evaluates to grammar file URI. Optional (as alternative to `src` or an inline grammar). If you specify this attribute, the element cannot have content. You can specify either `srcexpr` or `expr`, but not both. If you specify both, a parse error is thrown.
`expr`	Extension. JavaScript expression that evaluates to grammar file URI. Optional (as alternative to `src` or an inline grammar). Note: The `expr` attribute has been replaced by the `srcexpr` attribute and may be deprecated in a future release. If you specify this attribute, the element cannot have content. You can specify either `srcexpr` or `expr`, but not both. If you specify both, a parse error is thrown.
`method`	The query request method, either `get` or `post`. Optional (default is `get`).
`enctype`	MIME encoding used when submitting data with the post method. Optional (default is `application/x-www-form-urlencoded`). The supported types are: `application/x-www-form-urlencoded` `multipart/form-data` The type multipart/form-data is more efficient when submitting large amounts of binary data.
`namelist`	Space-separated list of variables to submit to the server. Optional (default is to submit no variables). This attribute can specify any variable currently in scope, both VoiceXML variables and JavaScript variables, including shadow variables and other variables that have not been explicitly declared. A variable set to a JavaScript object is submitted as the individual component values; see Submitting Complex JavaScript Objects.
`fetchhint`	Specifies whether the interpreter can attempt to optimize dialog interpretation by prefetching the resource. See Prefetching Resources. Optional.
`fetchtimeout`	Specifies the interval to wait for the resource to be returned before throwing a `error.badfetch` event. See Handling Fetching Delays. Optional.
`fetchaudio`	Specifies the URI of an audio clip to play while a resource is being fetched. See Background Audio. Optional. The specified audio clip is played only if the `bevocal.dtmf.flushbuffer` property is set to `true`.
`maxage`	Specifies the maximum acceptable age, in seconds, of the cached resource. See Maximum Age. Optional.
`maxstale`	Specifies the maximum acceptable time, in seconds, during which an expired cached resource can still be used. See Maximum Stale Time. Optional.

Parents	Children
`<bevocal:foreach>` `<block>` `<catch>` `<error>` `<filled>` `<foreach>` `<form>` `<help>` `<if>` `<noinput>` `<nomatch>` `<vxml>`	None.