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VoiceXML:
Forms, Menus, Grammars, Form
Interpretation Algorithm
Acknowledgements
 Prof. Mctear, Natural Language Processing,
http://www.infj.ulst.ac.uk/nlp/index.html, University of
Ulster.
Overview
 Forms
 Form items
 Form attributes
 Fields
 Field Attributes
 Prompts
 Menus
 Form Interpretation Algorithm
Forms
 Interpreting a form item (e.g. field)
 Select and play one or more prompts
 Collect user input
 Throw events (e.g. noinput)
 Interpret <filled> actions (procedural logic that executes when
input item variables are assigned)
 Form attributes
 id
name of the form e.g. <form id=“mainmenu”>
reference to another form <goto next=#validate”>
(validate is the name of a form)
 scope
scope of the form’s grammars e.g.
<scope = “dialog”>
Form Items
Input Items
<field>
<record>
<transfer>
<object>
<subdialog>
input using speech or DTMF
records user’s input as audio clip
transfers user to another telephone number
invokes a platform-specific object e.g. voice
authentication program
invokes another dialog
Control Items
<block>
procedural statements for prompting and
computation
<initial>
controls initial interaction in a mixed initiative
form
Example: A form for getting student
information
C: Say students, courses, or
reports
H: Students.
C: What is the student’s
name?
H: John Scott.
C: What is the student’s id?
H: 654556.
C: What information do you
require?
H: Address
The system prompts the
user for input in order
to fill in the required
fields.
The user responds to
the system’s
prompts.
The system accepts the
responses if they
match the grammars
for each field.
Fields
 The form for the previous example consists of 4 fields:
choice, student_name, student_id, info
 Each field has a prompt and a grammar
 Each field declares a variable which usually has the
value of ‘undefined’ when the field is first interpreted
 Field attributes
name
expr
cond
type
e.g. <field name=“choice”>
the initial value of the form item variable
a conditional expression e.g. to activate a field
only when another field has been filled
e.g. <field name=“student_id” type=“digits”>
Example
studentsystem1a.vxml
Headers (see next slide)
<form id="mainmenu" scope="dialog">
<field name="choice" modal="false">
<prompt version="1.0">
Welcome … To begin say one of the following: students, courses, reports
</prompt>
<grammar type="application/srgs+xml" root="choice" version="1.0"
mode="voice">
<rule id="choice" scope="public">
<one-of>
<item> students </item>
<item> courses </item>
<item> reports </item>
</one-of>
</rule>
</grammar>
</field>
</form>
</vxml>
Headers
IBM Voice Toolkit:
<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE vxml PUBLIC "-//W3C//DTD VOICEXML 2.0//EN"
"vxml20-1115.dtd">
<vxml version="2.0" xml:lang="en-GB"
xmlns="http://www.w3.org/2001/vxml">
<meta name="GENERATOR" content="Voice Toolkit for WebSphere
Studio" />
Bevocal:
<?xml version="1.0" ?>
<!DOCTYPE vxml
PUBLIC "-//BeVocal Inc//VoiceXML 2.0//EN"
"http://cafe.bevocal.com/libraries/dtd/vxml2-0-bevocal.dtd">
<vxml version="2.0" xmlns="http://www.w3.org/2001/vxml“
xml:lang="en-US">
Tutorial Exercises
 Exercise 1: Load and run the file
‘studentsystem1a.vxml’. The system will prompt you to
say one of: students, courses, details.
 Exercise 2: Create a file called ‘studentdetails.vxml’.
The file should have fields to elicit a student's name
and the name of a course. You will need to construct
grammars in each field containing a few names of
students and courses.
<prompt> (1)
 Bargein
 If an implementation platform supports bargein, the
application author can specify whether a user can
interrupt, or "bargein" on, a prompt using speech or DTMF
input
 To disable “bargein”:
<prompt bargein = “false>
 Timeout
 Specifies the interval of silence between prompt and user
input e.g.
<prompt timeout = “30s”>
 Default timeout value in Voice Toolkit is 7s.
 Timeout can be specified for individual prompts or set as a
property at a higher level e.g. in the root document
<prompt> (2)
 Count
 Used for prompts that change with each attempt to elicit input
e.g. to provide more help
<prompt count=“1”> what is the student’s id? </prompt>
<prompt count=“2”> please say the student’s id. It consists
of 6 digits </prompt>
 Conditional prompt
 Specifies that a prompt is only to be spoken if the condition is
true
<prompt cond=“now < 12"> Good morning </prompt>
<prompt cond=“now >= 19"> Good evening </prompt>
Menus
 A <menu> is a shorthand version of a form with a single
field that prompts the user to make a choice and then
transitions to another place (e.g. another dialog) based
on that choice
 Menu attributes
id
scope
dtmf
accept
e.g. <menu id=“mainmenu”>
grammar scope of the menu
when set to true, first nine choices are given the
implicit values ‘1’, ‘2’, etc (unless explicitly
specified)
default “exact” – defines the exact phrase to be
recognised
“approximate” – allows approximate recognition
Menu example
C: Welcome to the Student
System main menu
Please choose one of the
following options:
You can say student details,
course details, or records
H: Student details.
This example uses a menu to
present a choice to the
user.
The user selects one of the
options and the application
moves to the next dialogue
state.
<?xml version="1.0" encoding="iso-8859-1"?>
examplemenu1.vxml
<!DOCTYPE vxml PUBLIC "-//W3C//DTD VOICEXML 2.0//EN"
"vxml20-1115.dtd">
<vxml xmlns="http://www.w3.org/2001/vxml" xml:lang="en-GB"
version="2.0">
<menu id="mainmenu" scope="dialog" accept="exact" dtmf="false">
<prompt version="1.0">
To begin say one of the following:
</prompt>
<choice next=“studentdetails.vxml"> students </choice>
<choice next=“coursedetails.vxml"> courses </choice>

</menu>
</vxml>
Choice
 Can specify a speech grammar – may be automatically
generated
 Can specify a DTMF grammar
 Can use contents to form the <enumerate> prompt
string
 Specifies an event to be thrown or URI to go to when
the choice is selected
<choice next=“reports.vxml"> reports </choice>
Where to go to
Grammar for this choice
DTMF in Menus
 DTMF only
<menu>
<property name=“selected” value=“dtmf” />
<prompt> For reports press 1, etc </prompt>
<choice dtmf=“1” next=“reports.vxml” />
</menu>
 DTMF or speech
<menu>
<prompt> For reports press 1 or say ‘reports’ </prompt>
<choice dtmf = "1" next=“reports.vxml">reports
</choice>
</menu>
State transitions and branching
comment
<form>
<!– ‘choice’ field as in ‘studentsystem1a.vxml -->
<filled>
<if cond="choice == 'students'">
<goto next="studentdetails.vxml"/>
<elseif cond="choice == 'courses'"/>
<goto next="coursedetails.vxml"/>
<else/>
<goto next="reports.vxml"/>
</if>
</filled>
</form>
<filled> element
Executable code when
fields are filled
Conditionals
Requires documents to
be specified
Tutorial Exercises
 Exercise 3: Save the file ‘studentsystem1a.vxml as
studentsystem1b.vxml. Insert the additional code after
the end of the field </field> and before the end of the
form </form>.
 Note: To make this example work, it will be necessary to
create dummy files for the options for the transitions
specified in the <filled> element.
 Exercise 4: Load and run the file ‘examplemenu1.vxml’
Form Interpretation Algorithm
 Verification – verifying that the recognition result
corresponds to what the user said
 boolean builtin grammar
 Variables
 referencing variables
 declaring variables
 The Form Interpretation Algorithm (FIA)
viewdetails.vxml
<form id="student_details" scope="dialog">
<!– field to collect student_name -->
<field name="confirm" type="boolean" modal="false">
<prompt version="1.0">
you want details on <value expr="student_name"/>
</prompt>
<filled>
<if cond="confirm">
<prompt version="1.0"> looking up details on <value
expr="student_name"/>
</prompt>
<else/>
let's try again
<clear namelist="student_name confirm"/>
</if>
</filled>
</field>
</form>
Referencing a variable
you want details on <value expr="student_name"/>
 “student_name“ is the name of a field
 the expression retrieves the value of the field, i.e. the
value that was recognised by the system
 this value is not necessarily the value that the user
spoke e.g. if the input was misrecognised
More on Variables
<var> - declare a variable and possibly assign an initial value to it
<block>
<var name="status"/>

<var name="amount" expr = "13"/>

</block>
<assign> – assign a value to an existing variable
<block>
<var name="status"/>
<assign name = "status" expr = "completed"/>
<var name="amount" expr = "13"/>
<assign name = "amount" expr = "amount + 1"/>
</block>
Variables: More examples
 <var name = "revised_balance" expr =
"initial_balance + use_fee"/>

 <var name = "days_of_the_week" expr="new
Array()"/>

 <var name = "days_of_the_weekend" expr = "new
Array ('Saturday', 'Sunday') " />

Tutorial Exercises
 Exercise 4: Load and run the file ‘viewdetails.vxml’.
 In response to the prompt 'Please say the student name',
you can say one of: John, David, Rosemary, Jennifer.
 In response to the prompt asking for confirmation, you can
say either 'yes' or 'no'. Try both options.
 Exercise 5: Adding verification to studentdetails.vxml
 Using the file viewdetails.vxml as a basis, save the file
‘studentdetails.vxml’ as ‘studentdetails_confirm.vxml’.
Amend the file so that the system confirms the values
elicited (studentname, coursename). If the user confirms,
then the application terminates, otherwise it goes back to
elicit the values again.
Form Interpretation Algorithm
 The form interpretation algorithm (FIA) determines the
order of execution in a VoiceXML form or menu
 The FIA cycles through all of the fields in the form,
asking the caller to supply values for each unfilled field.
 The FIA provides the default sequence of processing
fields within a form; and thus hides the procedural
aspects of form processing the from the dialog
designer.
 Sometimes the fields of a form are “reset.” In this case,
the FIA will select the reset field during the next cycle
so all fields are filled eventually.
Form Interpretation Algorithm (FIA)
Amount
Source
Destination
Each field has a prompt and
a grammar (for user input)
The field variable is initially
set to ‘undefined’
When a field has been completed
the field variable is set to ‘true’.
The Form Interpretation Algorithm
skips fields that are ‘true’
Date
Confirm
If a field value is disconfirmed
the variable is re-set to ‘undefined’
FIA (continued)
Amount
Source
Destination
Date
Confirm
Amount and Destination were
disconfirmed
Their values are re-set to ‘undefined’
The FIA visits the ‘Amount’ and
‘Destination’ fields again until their
values are set to ‘true’
FIA: More detail
 Each variable (form-level <var> elements and form item
variables) is initialised to ‘undefined’
 The first form item whose guard condition is false
(undefined) is chosen to be visited.
 If no guard condition is false, then the FIA does an
implicit <exit> operation.
 <block> element
 form item variable set to true (cannot be visited again)
 content evaluated
 no input is collected
FIA in operation
Field
Before
Mid
Name
disconfirmed
Name
undefined
true
undefined
Course
undefined
true
true
Level
undefined
undefined
true
Date
undefined
undefined
true
More detail
Note that the FIA selects one item on each iteration e.g.
given the 4 fields above without any conditions on the
fields:
Iteration
1
2
3
4
5
6
By-passed item
None
name
name course
name course level
course level date
name course level date
Selected item
name
course
level
date
name
none: FIA exits
FIA example
<field name="confirm" >
<grammar
type="application/srgs+xml"
root = "yes_no“ version=“1.0”>
<rule id = "yes_no" scope =
"public">
<one-of>
<item>yes</item>
<item>no</item>
</one-of>
</rule>
</grammar>
<prompt>
You want details on <value
expr=“student_name"/>
</prompt>
</field>
<filled>
<if cond = "confirm == 'no'" >
<prompt>
Let's try again
</prompt>
<clear namelist =
“student_name confirm"/>

<else/>
<prompt>
Let's continue
</prompt>
</if>
</filled>
The <filled> element
 Defines how to process input-form-item variables after
they have values
 e.g. to check that the input is correct or to verify it with the
user (example: arrival time not earlier than departure
time)
 If the checking involves only the value of a single field,
the <filled> element is positioned within the <field>
element.
 If the check involves more than a single input-form-item
variable, the <filled> element is placed within the
<form> element.
Example: Validating the input
<form id=“get_details">
<!– The system has collected values for ‘source’ and
‘destination’ and checks that these are different
-->
<filled>
<if cond = “source == destination">
<prompt>
the destination and source accounts must be different
</prompt>
<clear namelist = “source destination"/>
</if>
</filled>
</form>
<if>
<if cond = "confirm == 'no'" >
<prompt> let's try again </prompt>
<clear namelist = “student_name confirm"/>
<else/>
<prompt>
Let's continue
</prompt>
</if>




“confirm” is the name of a field
The condition checks if the value of “confirm” is ‘no’
<clear> re-sets variables to ‘undefined’
namelist specifies which variables are to be re-set to
‘undefined’, otherwise all variables within the current
form are re-set
Tutorial Exercise
Exercise 5
1. Save the file ‘viewdetails.vxml’ as ‘newviewdetails.vxml’
2. Delete the line <clear namelist = "student_name
confirm" /> and see what happens.
3. Insert the line but delete the value ‘confirm’.
4. Try again, this time with ‘confirm’ included and
‘student_name’ deleted.
Exercise 6: Asking which item to confirm
 Scenario:
1. User has supplied values for studentname and
coursename
2. System verifies and user says ‘no’
3. System asks: which do you want to change ‘the student
name or the course name?’
<field name="change">
<prompt>
which item do you wish to
change: the student name or
the course name?
</prompt>
<!– insert grammar for each of
the 2 parameters -->
<filled>
<if cond="change == ‘student
name'">
<clear namelist=“student_name
confirm"/>
<elseif cond="change ==
‘course name'" />
<!– etc. -->
</if>
</filled>
<field name=“confirm” >
<prompt> so you want to details
on <value
expr=“student_name"/> taking
<value expr=“course_name"/>
</prompt>
<!– grammar for ‘yes/no’ -->
<filled>
<if cond="confirm==‘no’">
<goto nextitem = "change" />
<else />
<assign name="change"
expr="true" />
</if>
</filled>
</field>
<field name="change">
<prompt>
which item do you wish to
change: the student name or
the course name?
</prompt>
<!– insert grammar for each of the
2 parameters -->
The line <assign name=“change”
expr = “true” /> makes the value of
“change” be ‘true’ – this ensures
that the field will not be visited by
the FIA.

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