3 Trace Tool

The Trace Tool described in this chapter allows you to view the flow of a call and the caching of resources during an active call. The Trace Tool does not allow you to stop the flow nor does it provide you with state information. These things are provided by Vocal Debugger, which is described in Chapter 5, Vocal Debugger. Use these tools together to debug your application.

Note: To use the BeVocal tools, you must have the Java Runtime Environment (JRE) 1.5.7 installed on your computer.

As a phone call to an application progresses, the system records various messages to a log file. Click Trace Tool in the Tools & File Management menu to view log entries as they are generated.

When you click Trace Tool, the Trace Tool Command Area appears. The top portion of this window contains the Trace Command Area; the bottom portion contains the Trace Display Area.

The Trace Command Area contains:

•	Checkboxes that let you filter the messages displayed to those types that are of interest.
•	A Reload button, which lets you refresh the display when you update the selected message types.
•	A Reset button, which restores the filters to their most recently loaded values.
•	A Load default button, which lets you refresh the display with the default filters selected (displays all message types).
•	A View active calls button, which lets you select among the current list of active calls.

The trace message types are color-coded on the display and are described in the table below:

Message Type Used to Display

General Flow Trace

Major elements in the call progression, such as initializing form interpretation or adding a prompt to the prompt queue list.

Event Trace

Any events thrown by the interpreter or application, such as a no speech timeout event or a hang-up event.

Performance Data

Timing data, such as how long to fetch a grammar.

Variables Trace

Initial values and value changes to any JavaScript variables used in the VoiceXML application.

Error Message

Error conditions detected during the call that cause the interpreter to stop.

Custom Message

Messages from any VoiceXML <log> tags or use of the JavaScript bevocal.log command used in the VoiceXML application.

Call Control

Any use of the <transfer> tag or the JavaScript call-control extensions in BeVocal VoiceXML, such as bevocal:dial, bevocal:connect, and so on.

Platform

Low level platform messages, including playing stored audio prompts or text-to-speech (TTS) text.

Recognition Info

Attributes of a speech recognition, such as confidence level and the returned result.

HTTP Header Info

All HTTP header information when the application fetches any VoiceXML scripts or resources, such as audio prompts, grammars, or JavaScript files.

Warning Message

Error conditions detected during the call that do not cause the interpreter to stop.

Show Timestamp

A timestamp along with all the other message types.

.

Tracing a Call

To trace a call, simply select the call you want to trace.

1.	Click the View active calls button to view the list of currently active calls. If there are currently no active calls, you'll see a message to that effect. If this is the case, you can call an application on the system yourself and view the trace of your own call.
	Note: You may have to click the Reload button to update the display initially after the call begins.
2.	Click the View trace link for the call that interests you.

While the call is in progress, the display continually updates to show the log messages as they are generated.

After the call ends, the call session ended message is appended to the trace, as follows.

Tracing Flow Messages Only

You use the checkboxes in the Trace Command Area to select the message types that are of interest to you. For example, if you are interested only in messages that have to do with the general flow of the call, do the following:

1.	Click the View active calls button to select from the list of active calls. If no call is currently active, you can call an application on the system yourself.
	Note: You may have to click the Reload button to update the display initially after the call begins.
2.	Clear all checkboxes except the yellow one marked `General flow trace`.
3.	Click the Reload button.

Only general flow trace messages appear in the display and are updated as the call progresses.

[Show Frames] [FIRST] [PREVIOUS] [NEXT]

Message Type	Used to Display
General Flow Trace	Major elements in the call progression, such as initializing form interpretation or adding a prompt to the prompt queue list.
Event Trace	Any events thrown by the interpreter or application, such as a no speech timeout event or a hang-up event.
Performance Data	Timing data, such as how long to fetch a grammar.
Variables Trace	Initial values and value changes to any JavaScript variables used in the VoiceXML application.
Error Message	Error conditions detected during the call that cause the interpreter to stop.
Custom Message	Messages from any VoiceXML `<log>` tags or use of the JavaScript `bevocal.log` command used in the VoiceXML application.
Call Control	Any use of the `<transfer>` tag or the JavaScript call-control extensions in BeVocal VoiceXML, such as `bevocal:dial`, `bevocal:connect`, and so on.
Platform	Low level platform messages, including playing stored audio prompts or text-to-speech (TTS) text.
Recognition Info	Attributes of a speech recognition, such as confidence level and the returned result.
HTTP Header Info	All HTTP header information when the application fetches any VoiceXML scripts or resources, such as audio prompts, grammars, or JavaScript files.
Warning Message	Error conditions detected during the call that do not cause the interpreter to stop.
Show Timestamp	A timestamp along with all the other message types.