Voxeo Developer’s Corner

Greetings from the floor of O’Reilly’s Open Source Convention (OSCON) in Portland, ME…

As I said in the video, I’ll be speaking today at 5:20pm US Pacific time on the topic of “Mashing up Voice and the Web using Open Standards and XML” where I’ll be showing how you can use VoiceXML and CCXML to do interesting connections to “web 2.0″ sites. Needing a site to use for my examples, I decided to this round of demos with identi.ca, the new open source microblogging site (like Twitter, only open source).

Once my talk is over, I’ll post the slide deck here in this blog and also the code to the demos I’ve written. I’m looking forward to it… it should be fun! (If you’re here at OSCON, I will apparently be in room D137 at 5:20pm.)

P.S. You can also follow me on identi.ca at identi.ca/danyork

We all forget to make important calls from time-to-time. With this tutorial, you will be able to schedule a call ahead of time, so that Voxeo’s IVR system calls you at that time in the future, and then links you with the party you intended to call.

While you’re utilizing your free Voxeo developer account, you might as well keep the whole shabang free, right? Head on over to x10hosting.com or forwardhosting.com, and register for an account. These are two of the very few hosting companies that will allow you to run cron jobs for free. Now that you are all setup, let’s get into the design aspect, cron job first.

While cron web interfaces will certainly be different, the underlying principal is the same: cron will wait until the system time matches your job time, and then will execute an action. Most web portals to cron jobs will allow you specify minute, hour, day, month, and weekday.

Let’s assume you have to call your wife every Friday night at 5 pm to let her know that you’re coming straight home from work. We’ll set minute to “00″, the hour to “17″, the weekday to “4″, and the rest to “*”. This will make the cron job execute on Fridays at 1700. You may need to adjust the time on your cron job to account for differences between system time and your time. For example, the x10hosting box on which my cron job runs is set to US central time. For the cron job command, use the Unix command “curl” like so:

curl http://api.voxeo.net/SessionControl/CCXML10.start?tokenid=dd5a1d7f44e97f49856eb6e894c9c669d152e89a571f6201eb3b265045b7a1d2bb52ff8d9856fbbbbbbbbbba\&numdial=5551231234

This command sends an http request to api.voxeo.net for our CCXML 1.0 token. The request also contains the variable “numdial.”

( Please note that the backslash is used in cron to escape the ampersand. This request will not work properly from a browser window )

Now for the XML part:

<?xml version="1.0" encoding="UTF-8"?>
<ccxml version="1.0" xmlns:voxeo="http://community.voxeo.com/xmlns/ccxml">

<var name="state0" expr="'init'"/>
<var name="callid_out1"/>
<var name="callid_out2"/>
<var name="pin"/>
<var name="holdMusicDlg"/>

<eventprocessor statevariable="state0">

  <transition state="init" event="ccxml.loaded">
    <createcall dest="'tel:+15555555555'" connectionid="callid_out1" callerid="'1112223333'" timeout="'30s'"/>
  </transition>

  <transition state="init" event="connection.connected">
    <assign name="callid_out1" expr="event$.connectionid"/>
    <assign name="state0" expr="'enterpin'"/>
    <dialogstart src="'null://?termdigits=#&text=Press 1 and then pound if you want to dial' + session.values.numdial"&
    type="'application/x-fetchdigits'"/>
  </transition>

  <transition state="enterpin" event="dialog.exit">
    <log expr="'PIN = [' + event$.values.digits + ']‘”/>
    <if cond=”‘1′ != event$.values.digits”>
      <exit/>
    <else/>
      <assign name=”pin” expr=”event$.values.digits”/>
    </if>

    <assign name=”state0″ expr=”‘calling’”/>
    <dialogstart src=”‘holdingPattern.vxml’” type=”‘application/xml+vxml’” namelist=”pin” dialogid=”holdMusicDlg”/>
    <createcall dest=”‘tel:+1′ + session.values.numdial” connectionid=”callid_out2″ callerid=”‘5555555555′”/>

  </transition>

  <transition state=”calling” event=”connection.failed”>
    <assign name=”state0″ expr=”‘callfailed’”/>
    <dialogterminate dialogid=”holdMusicDlg”/>
  </transition>

  <transition state=”callfailed” event=”dialog.exit”>
    <assign name=”state0″ expr=”‘playingCallFailed’”/>
    <dialogstart src=”‘callFailure.vxml’” type=”‘application/xml+vxml’” connectionid=”callid_out1″/>
  </transition>

  <transition state=”playingCallFailed” event=”dialog.exit”>
    <disconnect/>
  </transition>

  <transition state=”calling” event=”connection.connected”>
    <if cond=”event$.connectionid == callid_out1″>
      <exit/>
    <else/>
      <assign name=”state0″ expr=”‘beforeBridging’”/>
      <dialogterminate dialogid=”holdMusicDlg”/>
    </if>
  </transition>

  <transition state=”beforeBridging” event=”dialog.exit”>
    <send name=”‘pause’” target=”session.id” delay=”‘200ms’”/>
  </transition>

  <transition state=”beforeBridging” event=”pause”>
    <assign name=”state0″ expr=”‘bridged’”/>
    <join id1=”callid_out1″ id2=”callid_out2″/>
  </transition>

  <transition event=”error.conference.join”>
    <log expr=”‘*** ERROR DURING JOIN ***’”/>
    <exit/>
  </transition>

  <transition event=”error.*”>
    <log expr=”‘an error has occured (’ + event$.reason + ‘)’”/>

    <voxeo:sendemail to=”‘yourEmail@there.com’”
      from=”‘myApp@here.com’”
      type=”‘debug’”
      body=” ‘generic error detected ! ‘ “/>
    <exit/>
  </transition>
</eventprocessor>
</ccxml>

This application has a fairly simple flow. It calls 1-555-555-5555, and then asks the callee to press 1 and then # to connect to whatever number was passed in via the http request (in this case numdial=5551231234).

That’s it. To make this work for you, you need to change four values:

1. token ID in http request
2. numdial variable in http request
3. “5555555555″ is found twice in the CCXML file - both instances should be changed to your number
4. sendemail “to” and “from” in CCXML file

Good luck with your development - mix in a little MySQL and PHP action to make adding more cron jobs easier.

Till next time,

Jeremy McCall
Voxeo Network Operations

This is a guest post from Mark Headd, a voice application developer who was one of the first 10,000 users of our platform, and was originally published on his Vox Populi blog on May 6, 2008.

---

A few weeks ago, I posted about accessing web services from CCXML using PHP. This post will demonstrate how to do the same thing, only from VoiceXML. We’ll be using Voxeo Prophecy and PHP for this example. We’ll also be referring to the GreenPhone project — available free for download — for the sample code.

Before we dive in, its important to keep in mind that there are a number of different techniques for getting information from web services into a VoiceXML dialog. This is just one method — there are many others. Voxeo even has its own platform-specific way of accessing SOAP web services via JavaScript. Ultimately, the method you employ needs to be a good fit for the environment your working in and the requirements of your project.

Using the greenSoapClient Class

In the last post on this topic, I demonstrated how to use a simple PHP class as a way to access multiple SOAP-based web services from CCXML. This class forms the basis of our method for accessing web services from VoiceXML as well. However, in this instance, instead of using the CCXML <send/> element, we’ll use a VoiceXML subdialog.

Subdialogs in VoiceXML are typically used to create reusable dialog components for capturing common types of input, like a series of digits (e.g., credit card numbers, account numbers, etc). They can also be used to compartmentalize complex interactions with a caller and provide a simple interface for accessing results. By way of example, this is how the OSDMs from Nuance work, as well as the Targus service from Voxeo. We’ll borrow this approach to access a web service from StrikeIron that will send the details of an E85 or bio-diesel station to a cell phone via SMS.

Setting up our Subdialog

In order to send an SMS message with details on an E85 or bio-diesel station, we’ll need 2 things; the station details, and a cell phone number to send it to.

In order to send the details on a station from VoiceXML to PHP, we’ll pack it up in a pipe-delimited string called “detailsToSend” (I won’t go into too much detail about how this is done in this post — to learn more, refer to the GreenPhone Project code). The cell phone number we are sending to is obtained from the caller ID of the calling party, stored in a variable named “ani”. Details on how to access caller ID are given in a previous post.

Our subdialog call will look like this:

<form id="sendDetails">
<catch event="error.badfetch">
<prompt>
There was a problem sending the station details to your phone.
<break strength="weak"/>
</prompt>
<goto next="#goodbye"/>
</catch>

<subdialog name="sendSMS" src="../php/sendStationDetails.php" namelist="ani detailsToSend">
<prompt>
Sending the station details to
<say-as interpret-as="telephone"><value expr="ani"/></say-as>
</prompt>
<filled>
<if cond="sendSMS.result==0">
<prompt>Your message has been sent.<break strength="weak"/></prompt>
<else/>
<prompt>
There was a problem sending the station details to your phone.
<break strength="weak"/>
</prompt>
</if>
<goto next="#goodbye"/>
</filled>
</subdialog>
</form>

We use the attributes on the <subdialog> element to give our subdialog a name (which we’ll use to access the results sent back from PHP), to specify where to POST our variables to and also to specify which variables to POST.

You’ll also notice that we have set up a handler here for an “error.badfetch” event. This is a good habit to get into whenever you set up a request to an external resource (like a PHP script). If the script isn’t there or has problems, an “error.badfetch” event will get returned and unless you specified a handler for this event, your day will not end well.

Additionally, we’ve set up logic in our filled block to inspect the result of the subdialog call. We access the result as a property of the subdialog, using the name we set up in the <subdialog> element and the dot notation (”.”) familiar to JavaScript.

<if cond=”sendSMS.result==0″>

… code logic goes here …

</if>

With this in mind, our PHP script needs to send back a variable called “result”. How do we do this? Lets take a look at the PHP script:

A Simple Subdialog using PHP

The subdialog that we want to render is extremely simple — we only need to render enough VoiceXML to declare a variable called “result” and return it to the parent dialog. We’ll do this after we make our web service call to send the SMS message.

There are two pieces of information returned from the StrikeIron web service that we are interested in; a string that holds the response message from the service (i.e., “success”, “failure”, etc.) and a number indicating the outcome of the web service call.

We’ll take these two bits if information and assign them to PHP variables:

$result = $xml->soapHeader->ResponseInfo->ResponseCode;
$message = $xml->soapHeader->ResponseInfo->Response;

Now, we want to write out these variables in a simple VoiceXML subdialog:

<?xml version="1.0" encoding="utf-8"?>
<vxml version="2.1" xmlns="http://www.w3.org/2001/vxml">
<form id="F_1">
<log>*** SMS response message was: <?php echo $message; ?>. ***</log>
<block>
<var name="result" expr="<?php echo $result ?>"/>
<return namelist="result"/>
</block>
</form>
</vxml>

As discussed above, this creates just enough VoiceXML to instantiate a variable and return it to the parent dialog. For good measure, we’ll write out the web service string (contained in the PHP variable $message) as a log statement, in case it contains information we want to look at later.

Why This Approach?

Using this technique for accessing web services from VoiceXML provides a couple of advantages. First, it allows us to completely separate the presentation layer (the VoiceXML) from the logic used to invoke the web service. This is a fairly standard design practice that makes creating the dialog much easier for a developer that does not necessarily know a whole lot about web services. With this approach, they don’t really need to — they only need to know that the subdialog call will return a variable called “result” whose value can be inspected to determine what to do next.

Additionally, because the parent dialog is just static VoiceXML it may be possible to cache it. Since the parent dialog isn’t dynamic, it can be cached for fast access, while the subdialog — which must be dynamic — is the only component sent from the web server to the VoiceXML platform each time a caller accesses the application. Careful design can yield additional caching opportunities that can make your applications more efficient and less bandwidth intensive.

In the next post, we’ll explore one additional method for accessing web service from VoiceXML. Stay tuned…

Technorati Tags:
voicexml, tutorials, php, voip, applications, phone, voxeo

This is a guest post from Mark Headd, a voice application developer who was one of the first 10,000 users of our platform, and was originally published on his Vox Populi blog on April 17, 2008.

---

Earth Day 2008 is fast approaching, so I wanted to try and build something that would help the environment and also be a cool demonstration of telephone applications generally, and the Voxeo Prophecy platform in particular.

I decided to whip up a simple application that would allow a caller to search for E85 and Bio-diesel fuel stations in their state. Some of the specific goals that I had in mind when I got started were:

• To make use of the Voxeo Prophecy platform, the premiere VoiceXML/CCXML platform for building voice applications (at least in my opinion).
• To code the application entirely in VoiceXML, CCXML, ECMAScript and PHP (that’s right, no database!).
• To integrate with SOAP-based web services to obtain data on E85 and Bi-Diesel station locations, and to do other cool stuff like send an SMS message from VoiceXML.
• To make use of interesting and unique audio files for prompts and to signal specific types of outcomes.

The fruits of one weekend of labor can be downloaded here. To set up and test this application, you will need the following:

• An account with StrikeIron to use the web services that drive the GreenPhone application.
• A copy of Voxeo Prophecy.
• A good headset and microphone (to place test calls using Prophecy).
• A cell phone (preferably one with a liberal text messaging contract).

Sign Up With StrikeIron:

Create an account with StrikeIron and sign up for the Super Data Pack Web Service. This is a collection of web services that allow for up to 10,000 hits / month at no charge (where are you going to get a better deal than that?). You’ll also want to sign up for the Global SMS Pro Web Service – this is the service that is used to send SMS messages from the GreenPhone application. Note – this service is priced quite differently than the Super Data Pack Web Service – only 10 free hits before you start paying. If you want to use this service for anything more than just testing out how to send an SMS message from Voxeo Prophecy, you’ll need to get your wallet out.

Make note of the user ID (email address) and password used to create your StrikeIron account – these will be needed momentarily.

Download and install Voxeo Prophecy:

Download and install the Voxeo Prophecy software. Follow all of the instructions for installing and obtaining a license – a two-port license (which will support 2 concurrent phone calls) is free. Right now, prophecy only runs on Windows, but a Linux version is in the pipeline.

Download and Configure GreenPhone:

Download the GreenPhone application and extract it to a new directory under c:\{Prophecy install path}\www\. (For example, on my Windows machine I’ve extracted to c:\Program Files\Voxeo\www\GreenPhone\). You don’t have to run the GreenPhone application on the same machine as Prophecy – if you decide to deploy it on another machine, it must support PHP 5 – GreenPhone makes use of the PHP SOAP and SimpleXML extensions.

Once this is complete, navigate to the directory where you just extracted the GreenPhone application files. Go to the directory called “php”, and open the file called common.php. At the top of this file, enter the credentials from your StrikeIron account. Save and close the file.

Creating a Call Route for GreenPhone:

Open the Prophecy Management Console in your web browser (http://127.0.0.1:9995/mc.php) – the default user ID and password are admin/admin. Click on the “Call Routing” option on the left hand menu – this is where you will set up a call route to the GreenPhone application.

Pick one of the numbered route Ids (e.g., Route 1 ID) and make the following changes:

• Change the route ID to green
• Change the Route Type to CCXML W3C
• Change the URL to http://127.0.0.1:9990/{ GreenPhone Install Directory}/greenPhoneStart.xml
• Scroll to the bottom of the page and click “Save Changes”

Making a test call:

Now that Prophecy is installed, fire up the SIP Phone that it is bundled with – you should see the Prophecy icon in your system tray. Click on it, and select “SIP Phone” from the menu. When the SIP Phone launches, select Options. In the SIP Proxy / Registrar Options section, enter your cell phone number in the Local Username field (e.g., 2125551234). Click OK, and restart your SIP Phone. This last step allows your cell phone number to be delivered as the caller ID (or ANI) on the test call you are about the make, even though your initiating the call from a SIP phone.

GreenPhone is built to use ANI to look up E85 and Bio-Diesel stations in the caller’s home state. We do this by invoking the U.S. Area Code Information Web Service that is part of the StrikeIron Super Data Pack to determine which state a caller is calling from. There are additional web services in the StrikeIron Super Data Pack that we can invoke to locate Bio-Diesel stations and E85 Stations — the methods invoked on these last two services require us to identify the state we want a listing of stations for.

The caller’s ANI is also used to send the details on a particular E85 or Bio-Diesel station via text message to the caller’s phone – so if you enter your cell phone number in the Voxeo SIP Phone as described above, you can get details on a station that may be near you sent directly to your cell phone.

As an aside, you’ll notice that a single phone call can result in up to 4 web service invocations — not really sure if that’s “too many” but there are probably some opportunities for caching that I’ll be discussing in the next couple of posts on this, as I describe in more detail how to interact with web services via Voxeo Prophecy.

Now you are ready to place a test call. When your SIP Phone restarts, go to the field called Dial String and enter “sip:green@127.0.0.1” (without the quotes). Click dial and you are now interacting with the GreenPhone application!

You’ll notice (and hopefully enjoy) the unique sounds I’ve tried to used throughout the application. All of them were obtained from the FreeSound Project and modified to conform to the Prophecy standard for audio files with Audacity.

There are some obvious limitations to how this application currently works, and the VUI clearly needs some refinement (DTMF only at this point).

In the next several posts, I’ll point to this application to discuss examples on how to accomplish things in VoiceXML and CCXML using the Voxeo Prophecy Platform.

Have a happy Earth Day on 4/22!!

What if you wanted to share your telephony “presence” information with another application? i.e. you wanted to let the application know whether or not you were on the phone? For instance, when someone called you a message that you were “on the phone” could then be displayed in the other application…. perhaps a web page with a directory of staff - showing who’s on the phone… perhaps an instant messaging client…

Well, out at eComm 2008 in March, our CTO, RJ Auburn, demonstrated exactly that kind of integration using just CCXML and web services. In his talk he showed a quick application in CCXML that would send out your presence information on the current web 2.0 darling Twitter. Essentially, what happens is this:

• Someone calls a phone number (presumably because you gave it to them)

• Call is connected to your actual phone
• Call presence information is sent out in your Twitter stream.

For instance, if you call one of these numbers (please do so only if you actually want to talk to me, and please only from 9am-5pm Eastern US time- thanks!):

• Direct Local # (857) 362-8469

• Skype +99000936 9996075436
• SIP VoIP sip:9996075436@sip.voxeo.net

You’ll reach me (or my voicemail) and the corresponding status updates will appear in my Twitter stream (shown in reverse chronological order):

Now I don’t know that I would really personally want to send out this information in my twitter stream every time someone called me (although in all honesty I don’t talk on the phone as much as I used to), but you get the idea. Your “telephony presence” can be sent out to another application. It’s to me a very cool example of how you can easily mashup voice with web services. While Twitter is used here for this example, the code could basically be used to send this presence information to any type of service that lets you communicate using simple web services. Let’s dive in a bit further…

The eComm Slides

First, though, I should mention that this example was part of RJ’s talk at eComm 2008 and you can see it in his slide deck starting at slide 27:

As soon as audio is available for the presentation, we’ll provide a link here to actually listen to the presentation.

The Web Service

Now to jump into the actual code, RJ was able to do this so easily largely because Twitter’s API is so incredibly simple to use, as I discussed in a previous post about Twitter. The full CCXML code is below, but here’s the key part where RJ defined the URL to use to update Twitter:

  <var name="tURL"
       expr="'http://zscgeek:password@twitter.com/statuses/

That’s it. (Note that while RJ is on Twitter as zscgeek, you can rest assured that his real password is NOT “password”!)

After creating this variable “tURL” (as in “target URL”), RJ proceeds to simply assign some text to a variable “status” and then call the target URL with that “status” variable as an argument. For example:

      <var name="status" expr="'RJ is on the phone'"/>
      <send targettype="'basichttp'" name="'update'"
            target="tURL" namelist="status"/>

Here “RJ is on the phone” is assigned to “status” and then the Twitter API is called. As shown in the code below, this same block of code is re-used with each different telephony state (and obviously with a different status message).

The Code

So here’s the code… nice and short and sweet… just enough to fit on a Keynote slide without straining eyesight (yes, it would probably fit on a PowerPoint slide, too, but remember that we’re Mac fans here). I’m not going to walk through each step of the code, but if you scan down you can see that basically the code is:

• Upon connection of the call:
  1. connecting the call to RJ’s cell phone (not his real number)
  2. sending the “RJ is on the phone” status update to Twitter
• Upon entering one of the other states (no answer, call disconnected), sending the appropriate Twitter status update.

Now if you aren’t familiar with the power of CCXML, you might want to look at our documentation and tutorial on CCXML or view one of the video tutorials on CCXML that we recently posted.

With that, here’s the code:

---

<?xml version="1.0" encoding="UTF-8"?>
<ccxml xmlns="http://www.w3.org/2002/09/ccxml" version="1.0">
  <var name="state" expr="'init'"/>
  <var name="incomingcall"/>
  <var name="tURL"
       expr="'http://zscgeek:password@twitter.com/statuses/update.xml'"/>
  <eventprocessor statevariable="state">
    <transition event="connection.alerting" state="init">
      <accept/>
    </transition>
    <transition event="connection.connected" state="init">
      <assign name="state" expr="'calling'"/>
      <assign name="incomingcall" expr="event$.connectionid"/>
      <createcall dest="'tel:+18315551111'"/>
    </transition>
    <transition event="connection.connected" state="calling">
      <assign name="state" expr="'connected'"/>
      <join id1="event$.connectionid" id2="incomingcall"/>
      <var name="status" expr="'RJ is on the phone'"/>
      <send targettype="'basichttp'" name="'update'"
            target="tURL" namelist="status"/>
    </transition>
    <transition event="connection.failed" state="calling">
      <assign name="state" expr="'done'"/>
      <var name="status" expr="'RJ is not answering his phone'"/>
      <send targettype="'basichttp'" name="'update'"
            target="tURL" namelist="status"/>
    </transition>
    <transition event="connection.disconnected" state="connected">
      <assign name="state" expr="'done'"/>
      <var name="status" expr="'RJ is off the phone'"/>
      <send targettype="'basichttp'" name="'update'"
            target="tURL" namelist="status"/>
    </transition>
    <transition event="send.successful" state="done">
      <exit/>
    </transition>
  </eventprocessor>
</ccxml>

---

Feel free to use it, modify it, etc., etc. (And if you do something cool with it, please do let us know, either as a reply to this post or via email.) While this is with Twitter, we’d love to hear where else you can think of sending telephony presence info…

P.S. If you’d like to experiment with this but are not sure of how to get started, head on over to www.voxeo.com/free and either sign up for a free developer account on our Evolution portal or download our free Prophecy software to run it on your own server.

Technorati Tags:
applications, ccxml, xml, voice, voice mashups, mashups, voxeo, twitter, presence, telephony, phone mashups

Just a brief update on my piece about how to use voice with Google’s App Engine… I now have been invited into the preview of Google’s App Engine, so I’ve created a second application on our Evolution platform with this one pointing to my shiny new GAE app at:

http://voicexmltest2.appspot.com/

For now, it’s the same (lame) python code, but the app does have it’s own phone numbers:

Direct Local #	(857) 362-8430
PIN Access	(800) 289-5570 then PIN: 9996075378
PIN Access	(407) 386-2174 then PIN: 9996075378
Skype VoIP	+99000936 9996075378
FWD VoIP	**86919996075378
SIP VoIP	sip:9996075378@sip.voxeo.net

Why didn’t I simply modify the original Evolution application? Well, I could have, but I figured this way I can also still experiment with the AppDrop.com application as well.

The nice thing with a true Google App Engine account is that I can use “appcfg.py” to automagically update the files up on the App Engine site, which is very slick. (Thanks, Google, for the invite!) Next week, my intent is to work with the python code to get it actually manipulating the XML… stay tuned… (and check my original article if you would like to experiment with voice and Google App Engine, too).

Technorati Tags:
application platforms, applications, google, appengine, google appengine, , voxeo, voicexml, python, xml, voice, voice apps, voice applications

Update 2008 Apr 18: I now have an App Engine account and have the app running there as well.

---

Could Google’s AppEngine, the buzz of the developer world right now, be used to create voice applications? That was the question I asked myself and the answer is something you can test yourself by calling one of these numbers (since we support all these forms of calling):

• (857) 362-8441 (or +1-857-362-8441 outside North America)
• Skype: +99000936 9996071593
• SIP: sip:9996071593@sip.voxeo.net

Assuming I haven’t changed the app since writing this post, you should simply hear some text “Your magic number is (some number)…” and then a pointer to this blog site. If you call the number again, you’ll hear the text with a different number. And again and again.

So what’s going on here? Well, you have:

• dynamic generation of a VoiceXML application
• using the python language and Google’s AppEngine SDK
• running on Amazon’s Elastic Compute Cloud (EC2) hosted computing environment via AppDrop.com
• with the phone interface provided by our (Voxeo) Evolution hosted platform

Got all that? Let’s take a look at how the pieces fit together

Google’s AppEngine

Last week Google announced the release of their AppEngine developer tool that lets you run web applications on Google’s massive infrastructure. Basically, you develop your application (currently only in the python language), upload it to Google’s servers and let Google’s infrastructure take care of all the rest. In addition to their web server and distributed database, you also have access to using Google Accounts for usernames which means you don’t have to create your own usernames and passwords (although you are then obviously tied to Google for authentication).

This announcement was immediately the subject of a huge amount of buzz throughout the blogosphere and the web in general. Unfortunately, only the first 10,000 developers could get in to try it out. While they let 10,000 more developers in yesterday, I’m still not one of them. However, I could download the AppEngine SDK and, dusting off my rusty memory of python (which I used to do a lot with) put together a quick program that would dynamically generate a VoiceXML file.

If your browser will display an XML file as raw XML, you can see the result here:

http://voicexmltest.appdrop.com/

If your browser won’t display raw XML, here’s a screenshot of what it should look like:

Your number should be different because it is being randomly generated. If you refresh your browser you should now see a different number in the <prompt> text. I did all this locally using the AppEngine SDK, saw that it generated valid (and dynamic) VoiceXML, and then needed to figure out where to host this so that I could demonstrate the usage - without a Google AppEngine account.

Amazon’s EC2 and AppDrop.com

While I’ve been patiently waiting for Google to send me an email letting me into the AppEngine preview, I stumbled upon the news that Google’s App Engine had been ported to Amazon’s EC2 service. Developer Chris Anderson announced a new service called AppDrop.com which basically hosts a modified version of Google’s AppEngine code on Amazon’s EC2 service. It obviously doesn’t support all of Google’s services like the distributed database or Google Accounts for authentication, but it allows you to develop an app with the AppEngine SDK and then upload it to the AppDrop service. Philosophically, I found this an interesting demonstration that using the AppEngine SDK did not necessarily lock you in to Google’s platform.

More importantly to me, I could create a hosted AppDrop.com application now without yet having my Google AppEngine account (subject to the caveats that AppDrop.com is entirely a proof-of-concept, it may go away at anytime, etc, etc.). So I did. Here’s the steps:

1. Download the modified Google AppEngine SDK from AppDrop.com. It’s essentially the same thing as the Google SDK but with modifications for the lack of support for Google’s database, accounts, etc.

2. Create an app in the local SDK. (I just literally copied my files from the Google AppEngine SDK directory over into the AppDrop SDK directory.)
3. Register an app on AppDrop.com. This was not entirely intuitive as nowhere on the main page does it tell you how to do this. However, if you go to the list of current applications, there is a “Make a new app” link that takes you through the process of creating a new account on the site and then registering the app.
4. Create a gzipped tar file of your application to upload. Easiest way is on the command line go into the directory containing your app and type “tar -cvzf <appname>.tar.gz *“. (This is taken care of for you in the actual Google environment with “app_cfg.py”, but no such automated script is available for AppDrop.com yet, although they are working on one.)
5. Upload the file via the AppDrop.com web interface. If it works you get a simple “Upload successful” page.
6. Go to http://<appname>.appdrop.com/ to see the resulting app. For instance, http://voicexmltest.appdrop.com

With that, I now had a publicly hosted app developed on the Google AppEngine SDK.

Voxeo’s Evolution platform

The last step was to provide the phone interface to this voice app and for that I obviously used our Evolution platform. Using my free developer account (which anyone can get), I basically followed the steps of our Quick Start Guide:

1. Once logged into Evolution, I clicked on “Application Manager”.
2. I clicked on “Add Application”.
3. For the development platform, I chose “Prophecy 8.0 - VoiceXML 2.1″
4. On the next screen, I completed the form as follows:
   1. Entered a name of the application.

   2. In the “Start URL 1″ box, I entered the URL to my AppDrop.com application - including the trailing slash (very important!)
   3. Under “Application Phone Number” chose the region in which I wanted a phone number. (If you don’t do this, you can still access your application via SIP or Skype, but not direct-dial from the PSTN. And yes, for the free accounts we only give out US phone numbers.)
5. I clicked the “Create Application” button and my application was done.

Here’s a screen shot of that part of the screen for my app:

Do note again that I included the trailing slash on “http://voicexmltest.appdrop.com/”.

If I click on the “Phone Numbers” tab I can see the various numbers that I can use to call into this application:

That’s it! Assuming you are generating correct VoiceXML code, when you call into those numbers you should hear the voice app you created.

Show Me The Code!

So if you’ve read this far I imagine you probably want to see the actual code I wrote, eh?

Well, there are two files needed in a Google AppEngine SDK directory. First you need a file called “app.yaml” that simply provides the name of your app and the name of the main python file (here brilliantly called “main.py”):

application: voicexmltest
version: 1
runtime: python
api_version: 1

handlers:
- url: .*
  script: main.py

The second file is the “main.py” python file (which could be called anything as long as it matches what is in the app.yaml file). To be honest, my file is embarrassingly lame as a python app goes but as long as you recite “Remember this was a quick lunch-time hack as a proof of concept”, here it is:

#!/user/bin/env/python
import random

def main():
  print '''<?xml version="1.0" encoding="UTF-8"?>
<vxml version = "2.1" >
  <form>
    <block>
    <prompt>
'''
  print "Hello! Your magic number today is %d. " % random.randrange(100)
  print '''
     To learn more about this application, please visit blogs dot voxeo dot
     com. Thank you for calling this app.
    </prompt>
    </block>
  </form>
</vxml>
'''

if __name__ == "__main__":
  main()

Like I said, it’s a very simple app that really doesn’t even remotely begin to demonstrate the power of either python or VoiceXML. (Remember “quick proof-of-concept”.) For those not familiar with python or VoiceXML, here is what the main() function does:

• prints out the first half of the VoiceXML file

• prints out the dynamically generated part with a random number
• prints out the second half of the VoiceXML file

Basically a glorified “Hello, world!” program with a random number thrown in. If you’re not familiar with the python construction I’m using here to print these large blocks of text, what I’m doing is putting three single apostrophes together to mark the beginning of the block of text and then three single apostrophes at the end to close off the block. It’s a great way to do simple hacks like this one.

Next Steps

So with the embarrassment of that python file out of the way and now that I’ve proven to myself that you can develop voice apps using Google’s AppEngine (at least via AppDrop), what’s next? Well, when I next get a chance to work on it, I’m going to do two things. First, I’ll do more with VoiceXML, since there’s so much more it can do. Maybe add in some speech recognition, multiple call paths, maybe even upload some small audio files for prompts. Perhaps I’ll play with some outbound dialling and call transfer. Or wrap the VoiceXML inside of a Call Control XML (CCXML) app.

Second, and perhaps more useful to demonstrate Google’s AppEngine, I want to change the python code to actually manipulate the XML rather than simply printing out the XML code as text. There’s a great amount that can be done with python and XML, and even a book on the subject (which happens to be on my bookshelf), so the resources are out there.

In the meantime, though, I would be curious to see what any of you all can do with these pieces. What do you think about using Google’s App Engine to host applications in this way? If you can easily use a language like python to manipulate data and dynamically generate voice apps (using VoiceXML), what can you think of to do with it? What kind of apps will you write?

Do any of you want to give it a try? The steps are really quite simple:

1. Download either the Google App Engine SDK, or, if like me you don’t have a Google App Engine account yet, download the AppDrop.com modified SDK.
2. Write your python app locally (Google has intructions and examples) that generates valid VoiceXML (we have tutorials there).
3. Upload the app to either Google or AppDrop.com.
4. Create an Evolution account if you don’t have one and follow the steps above to create the app on our service.
5. Call it up and see how it works.

If you do anything cool with it, please definitely do leave a comment as I’d love to check out what you do (and hey, maybe even spotlight it here on the blog if you are open to that).

With that, I’m going to turn back to experimenting with python and XML… (oh, and waiting for my App Engine invite… hint, hint, Google!)

Technorati Tags:
application platforms, applications, google, appengine, google appengine, amazon, ec2, amazon ec2, appdrop, voxeo, voicexml, python, xml, voice, voice apps, voice applications