Building Tropo Apps with Grails

Building Tropo Appswith GrailsChristopher Bartling

Summary 2■ What is Tropo?■ How do I integrate Tropo with Grails?■ Tropo WebAPI overview■ Lessons learned

Terminology 3■ IVR: Interactive Voice Response■ VoiceXML or VXML:■ CCXML: Call Control XML■ TTS: Text to Speech

What is Tropo? 4■ Cloud-based services for telephony and messaging ■ Make and receive phone calls ■ Use voice recognition ■ Messaging via SMS, IM, or Twitter■ Backed by Voxeo.com ■ Industry leader in IVR and VoIP solutions

Why should I care? 5■ Many applications beneﬁt from voice and messaging user interfaces■ Tropo provides telephony and messaging infrastructure and APIs for integrating these services into your applications ■ Traditionally this was hosted in-house■ APIs insulate developers from needing to write in VoiceXML, CCXML, and other markups

How do I use it with Grails? 6■ Install the Tropo WebAPI Grails plugin (version 0.21) ■ tropo-webapi-grails ■ Provides the TropoBuilder object for building standard Tropo JSON documents ■ TropoService for provisioning and servicing Tropo applications

TropoBuilder 7■ Builds Tropo JSON response documents■ Provides an array of JSON objects to control the Tropo-based applications hosted in the cloud ■ ask, call, conference, hangup, message, on, record, redirect, reject, result, say, session, startRecording, stopRecording, transfer

TropoService 8■ Grails service for administering Tropo applications ■ Abstraction around Tropo’s REST API ■ Create, update, and delete Tropo applications ■ Provision phone numbers, IM addresses, tokens ■ Retrieve information about applications

Tropo.com 9■ Web-based administration UI ■ Create, update, and delete Tropo applications in the cloud ■ Provision telephone numbers (both local and toll- free) and IM accounts for your applications ■ Application debugging tool ■ Billing proﬁle

Tropo Development 10■ Create your Grails application■ Add tropo-webapi-grails Grails plugin■ Create your starting endpoint in your Grails app■ Create application on tropo.com ■ Need externally available starting endpoint for your Grails app ■ Provision local phone number

Tropo WebAPI 11■ Use the TropoBuilder object to create Tropo-compliant JSON objects■ Tropo calls back to your application for instructions on how to power the IVR infrastructure in the Tropo cloud■ You application is a collection of interconnected endpoints, rendering Tropo JSON objects to control the IVR infrastructure in the Tropo cloud

Tropo WebAPI JSON objects 12

session 13■ Sent to your application in the first Tropo request■ The callId field identifies this request body to a unique call in Tropo ■ You will use the callId as the correlation identifier for all requests■ https://www.tropo.com/docs/webapi/session.htm

result 14■ Sent to your application in all subsequent requests from Tropo■ The callId field identifies this request body to a unique call in Tropo ■ You will use the callId as the correlation identifier for all requests■ https://www.tropo.com/docs/webapi/result.htm

say 15■ Say something to the caller ■ Can be TTS or pre-recorded audio ■ Does not wait for user response■ https://www.tropo.com/docs/webapi/say.htm

ask 16■ Say something to the caller and wait for a response from the caller ■ Can be TTS or audio ﬁle for say ■ Response can be collected speech or touch-tone keypad (DTMF) ■ The choices object speciﬁes how Tropo handles user input■ https://www.tropo.com/docs/webapi/ask.htm

on 17■ Speciﬁes event handling ■ continue ■ error ■ incomplete ■ hangup■ https://www.tropo.com/docs/webapi/on.htm

hangup 18■ Hangs up the current call.■ https://www.tropo.com/docs/webapi/hangup.htm

record 19■ Plays a prompt and then waits for a response from the caller, which it records■ Responses may be speech recognition or touch-tone keypresses (DTMF)■ At the conclusion of the recording, the collected audio ﬁle is sent to FTP or HTTP POST/Multipart Form endpoint

transfer 20■ Transfer an in-progress call to another destination or phone number ■ Can be a phone number or a SIP address■ https://www.tropo.com/docs/webapi/transfer.htm

startRecordingstopRecording 21■ Start and stop recording a call session■ Resultant recording can be sent via FTP or HTTP POST/Multipart form to a URL■ You have to provide an endpoint or FTP server to receive the binary ﬁle■ https://www.tropo.com/docs/webapi/startrecording.htm■ https://www.tropo.com/docs/webapi/stoprecording.htm

Lessons Learned 22■ Testing ■ Test call ﬂow in isolation by using a testing Tropo application and a testing endpoint to bootstrap the call session appropriately ■ In the future, look to building an automated test runner that can be scripted and exercise the Grails app through HTTP calls

Lessons Learned 23■ The ask noinput and timeout APIs don’t work well ■ Issues with audio getting played out of sequence ■ Build this functionality into our call ﬂow explicitly using on events

Lessons Learned 24■ Call recording is all or nothing ■ Unable to start and stop recording to allow for omission of sensitive data recording ■ We toggle recording for debugging call ﬂow ■ Keep it off for production usage

Lessons Learned 25■ Call duration can be difﬁcult to determine ■ Maintain a last Tropo callback timestamp on call session domain object ■ Update the timestamp on each Tropo callback invocation ■ Allows approximation of the call duration

Lessons Learned 26■ Abandoned calls can be difﬁcult to determine ■ We used a Quartz job in Grails ■ Periodically inspect in-progress calls ■ If last Tropo callback timestamp is beyond a speciﬁed threshold, set the call session to abandoned

Contact Information 27■ Twitter: @cbartling■ Blog: http://bartling.blogspot.com■ https://bitbucket.org/cebartling/tropo-presentations

Building Tropo Apps with Grails

by Christopher Bartling

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