The document provides an overview of integrating Tropo with Grails, outlining Tropo's cloud-based telephony and messaging services, including voice recognition and SMS. It discusses the use of the Tropo WebAPI, the TropoBuilder object for creating JSON response documents, and the TropoService for managing applications. A series of lessons learned from development and testing processes are also highlighted, addressing issues and best practices in using Tropo with Grails.

1. Building Tropo Apps
with Grails
Christopher Bartling

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

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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. 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

12. Tropo WebAPI JSON objects 12

13. 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

14. 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

15. 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

16. 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

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

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

19. 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

20. 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

21. startRecording
stopRecording 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

22. 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

23. 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

24. 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

25. 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

26. 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

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