Voxeo Developer’s Corner

I am happy to announce a new semi-regular addition to the Voxeo blog, where the Voxeo Support team will be adding VoiceXML, CallXML, and CCXML tips, tricks, and best practices for our developers, which we will christen as “Certified Tech Tips”. The name has a nice ring to it and all, but this isn’t just for show: 100% of the technical support team are certified VoiceXML developers, and we are pretty proud of being the only provider who holds these standards.

As we devise some really inventive means of achieving project goals & cool functionality when coding in the framework of these various IVR markups, we thought that we might share some of these tips to our readers of the Voxeo Blog.

For those who haven’t interacted with the support team yet, a bit of introduction is in order. My name is Matthew Henry, and serve as the Director of Customer Support here at Voxeo. I have been with the company since it’s inception (way back in the 20th Century), and have been lucky enough to work with a sizable number of really talented IVR developers and engineers, which has allowed me to learn a lot, and has also allowed me to build up a respectable code library for all things IVR. And now, it’s time for some payback.

=^)

As our maiden posting to the Voxeo blog, we will cover the topic of Semantic Interpretation for Speech Recognition-formatted grammar returns when using the Prophecy 8 software. A lot of folks are used to using plain-old Nuance GSL grammars due to it’s ease of use and concise markup, but the drawback of using this approach is pretty fundamental: As GSL is Nuance-specific, it isn’t guaranteed that every provider will support it. And those of us who have written complex grammars know that porting a grammar can be a tedious job to take on. For this reason, we always suggest that folks stick with a W3C standard when writing grammars, that being using the SRGS XML-based grammar format that leverages the SISR syntax to populate our grammar interpretations back to the VoiceXML dialog. Most of the documentation on our site references using the Nuance-specific return formatting, and today we will show you what a 100% w3c compliant grammar looks like.

To start things off, let’s take a look at some GSL, and some SRGS with Nuance-specific returns for the sake of comparison:

Simple GSL

MYRULENAME [
[utterance]      {<mySlotName  “my return value”>}
]

Simple SRGS with Nuance-returns

<?xml version= "1.0"?>
    <grammar xmlns=”http://www.w3.org/2001/06/grammar” xml:lang=”en-US”
        root = “MYRULENAME”>
      <rule id=”MYRULENAME”>
        <one-of>
          <item>
   	       utterance
	       <tag> <![CDATA[  <mySlotName "my return value"> ]]>  </tag>
          </item>
        </one-of>
      </rule>
    </grammar>

Simple SRGS with SISR returns

<?xml version= "1.0"?>
    <grammar xmlns=”http://www.w3.org/2001/06/grammar” xml:lang=”en-US”
          root = “MYRULENAME”>
      <rule id=”MYRULENAME”>
        <one-of>
          <item>
               utterance
	       <tag>$.mySlotName = “my return value”</tag>
	  </item>
        </one-of>
      </rule>
    </grammar>

The differences in syntax are fairly self-evident in these cases. In the case of SISR, the “$.” prefix allows us to specify any slotname that we will return to our VoiceXML dialog, and specifying a quoted interpretation value preceded by an ‘equals’ sign links the value to this slot.

In addition, we can also specify a “generic” return where no slotname is specified (which comes in handy for subgrammars) by putting $=”my return value” within the . If we want to get really fancy, we can even specify multiple slots to return back to the dialog by inserting a “;” delimiter between the slot/interpretation pairing. A sample multislot return with an “anonymous” slot also defined might look something like this:

<item>
    utterance
    <tag>
    $ = “my anonymous slot value”;
    $.mySlotName1=”my slot 1 return”;	 $.mySlotName2=”my slot 2 return”;
    </tag>
</item>

As you can see, the SISR returns are much more concise, easy to read, and much more lightweight than Nuance-specific returns. And once you write a grammar using SIRGS and SISR, then any Certified Compliant VoiceXML platform will run these grammars without any porting at all being required.

If you found this posting useful, then let us know! Mayhap we will dig deeper into this the next time, and whip out some more complex subgrammars to better illustrate the usage of SISR formatting within your IVR applications.

Till next time!
~Matthew Henry

Tags: grammars, SISR, VoiceXML

You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.