VoiceXML: Events, Errors, and ECMAScript

1
VoiceXMLEvents, Errors, and ECMAScript
2
Acknowledgements

• Prof. Mctear, Natural Language Processing,
  http//www.infj.ulst.ac.uk/nlp/index.html,
  University of Ulster.

3
Events

1. Plain events happen normally, involve special
   event handler
2. Error events - unexpected situations, may cause
   application to terminate

Plain events Error events
cancel, help, exit (user) error.badfetch
noinput, nomatch (user input) error.semantic
connection.disconnect.hangup error.noauthorization
maxspeechtimeout error.unsupported.builtin
Note how events are handled is platform-dependent
4
Default catch handlers
Event Type Action
cancel dont reprompt
error exit interpreter
exit exit interpreter
help reprompt
noinput reprompt
nomatch reprompt
maxspeechtimeout reprompt
connection.disconnect exit interpreter
all others exit interpreter
5
noinput, nomatch

• ltnoinputgt
• System does not detect any speech.
• This event is thrown when the timeout interval is
  exceeded (in IBM WebSphere Voice Toolkit the
  default timeout interval is 500 milliseconds).
• ltnomatchgt
• The users input does not match the recognition
  grammar.
• The default behaviour in the IBM WebSphere Voice
  Toolkit for this event is to output a message and
  then re-prompt.
• These (and other) default event handlers can be
  modified.
• Properties such as timeout can also be modified.

6
ltcatchgt

• ltcatch event "nomatch"gt           ltpromptgt  I
  did not understand what you said. Please answer
  the question again. lt/promptgtlt/catchgt
• ltcatch event "nomatch noinput help"gt         
    ltpromptgt  I did not understand what you said.
  Please answer the question again. lt/promptgt 
  ltreprompt/gt  lt!--  Present the original prompt
  message again to the user   --gtlt/catchgt
• ltcatch event "nomatch" count "2"gt
•   lt!--  count different occurrences of an event
    --gt

7
Shorthand ltcatchgt elements

• Some common events, such as noinput, nomatch,
  help, and error have shorthand versions, e.g.
• ltnomatchgt     I did not understand, please try
  again.lt/nomatchgt
• ltnoinputgt
• I didnt hear anything. Please speak a little
  louder.
• ltnoinputgt
• With counters ltnomatch count 1gt

8
ltthrowgt

• Used to define application-specific events e.g.
  user has failed 3 times to enter valid id
• ltcatch event nomatch" count "1gt
• That is not a valid i d   lt/catchgt
• ltcatch event "nomatch" count "4gt
• ltthrow event "error.invalid_password"/gt
  lt/catchgt
• ltcatch event "error.invalid_password" gt
• ltpromptgt Please check your i d. Goodbye lt/promptgt
• ltexit/gt
• lt/catchgt    

9
Event handlers and scope

• Event handlers can be defined at different scope
  levels
• Scope levels form a hierarchy.  
• Event handlers defined in a higher scope level
  are inherited at lower scope levels within the
  hierarchy. 
• A local event handler overrides or replaces an
  inherited event handler.  If a local event
  handler has the same name as an inherited event
  handler, then the local event handler replaces
  the inherited event handler.
• The VoiceXML interpreter examines the following
  containers in the order listed to select an event
  handler
• Field
• Dialog
• Document
• Application
• Session

10
Tutorial Exercises Error handling

• Aim to explore events such as ltnoinputgt and
  ltnomatchgt and modify their default behaviours
• Run the file studentsystem1b.vxml and test how
  it behaves when a) You do not say anything b)
  You say something that is not in the specified
  recognition vocabulary.
• Modify the default behaviours for ltnoinputgt and
  ltnomatchgt using counters for alternative
  behaviours.
• Define an application specific event using
  ltthrowgt that causes the application to terminate
  with some form of explanation following an event
  such as repeated failure to elicit valid input.
• The event could be a third failure to elicit the
  users spoken input, with an event thrown such as
  error.no_input. This event can be caught,
  causing the system to transfer to a human
  operator. Include a prompt that explains what is
  happening. If transfer is not possible, then use
  ltexit /gt or ltdisconnect/gt to cause the
  application to terminate.

11
What is ECMAScript?

• Used as the scripting language of VoiceXML for
  client-side processing, e.g. to validate user
  input (without requiring access to the server),
  or to dynamically generate values.
• VoiceXML variables are completely equivalent to
  ECMAScript variables.
• The expr and the cond attributes reference
  ECMAScript expressions.
• Escaping characters to conform to the rules of
  XML e.g.ltif cond age gt 21 gt
• Or use the ltscriptgt element e.g.
• ltSCRIPTgt
• lt!CDATA
• ... ECMAScript code ... gt
• lt/SCRIPTgt

http//www.ecma-international.org/publications/sta
ndards/Ecma-262.htm
12
ECMAScript Example

• ltform id"form"gt
• ltblockgt
• ltvar name"hours"/gt
• ltvar name"minutes"/gt
• ltvar name"seconds"/gt
• ltscriptgt
• lt!CDATA
• var nownew Date()
• hoursnow.getHours()
• minutesnow.getMinutes()
• secondsnow.getSeconds()
• gt
• lt/scriptgt

ltpromptgt The current time is ltvalue
expr"hours"/gt hours, ltvalue expr "minutes"/gt
minutes, and ltvalue expr "seconds"/gt
seconds. lt/promptgt lt/blockgt lt/formgt
13
More on the date object

• The Date object stores a year, month, day, date,
  hour, minute, and second.   
• Methods of the Date object include
• getSeconds( ) returns the seconds in Date
• get Minutes( ) returns the minutes in Date
• getHours( ) returns the hours in Date
• getDay( ) returns the day of the week in Date
  beginning at 0
• getDate( ) returns the day of the month in Date
• getMonth( ) returns the month in Date beginning
  at 0
• getFullYear( ) returns the year as a 4 digit
  string

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Example with ltifgt Calculating variable interest

• ltform id"calculate_interest"gt
• ltvar name interest"/gt
• ltvar name"interest_calculated" /gt
• ltfield name"amount typenumbergt
• ltpromptgtWhat is the amount in your account?
  lt/promptgt
• ltfilledgt
• ltscriptgt
• lt!CDATA
• if (amount lt 1000) interest 0.02
• if (amount gt 1000 amount lt 10000)
  interest 0.03
• if (amount gt 10000) interest 0.04
• interest_calculated interest amount
• gt
• lt/scriptgt
• ltpromptgt the interest on your balance is ltvalue
  expr"interest_calculated"/gt lt/promptgt
• lt/filledgt
• lt/fieldgt
• lt/formgt

15
Tutorial Exercise ECMAScript

• Using the file interest.vxml as a basis, create
  a file called commission.vxml that elicits the
  selling price of a property and then calculates
  the commission fee based on the following rules
• if (amount lt 90000) fee 0.05
• if (amount gt 90000 amount lt 200000) fee
  0.04
• if (amount gt 200000) fee 0.03

16
Universal Commands and Navigation
17
Overview

• Using a root document for global commands and
  storing information
• Navigation within and between documents
• The ltsubdialoggt element
• Exercises
• Using a root document
• Creating a subdialog

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Root document

• Simple applications may consist of one document.
• Larger applications may consist of several
  documents, one of which is the root document, and
  the others are child documents of the root
  document.
• The root document can contain event handlers,
  grammars, variables, scripts and other constructs
  in the scope of the application which are
  inherited by the child documents.
• These elements are active throughout the entire
  application, unless otherwise specified.
• The child documents must reference the root
  document using the application attribute of the
  ltvxmlgt element, e.g.ltvxml version2.0" applicati
  on"root.vxml"gt
• (assuming root document is called root.vxml
  Note the root document can have any arbitrary
  name)

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root.vxml

• lt!-- header information --gt
• ltvar nameuser_pin"/gt
• ltlink next"main.vxml" gt
• ltgrammar type"application/srgsxml" root"main"
  version"1.0" mode"voice"gt
• ltrule id"main" scope"public"gt
• ltone-ofgt
• ltitemgt main menu lt/itemgt
• ltitemgt start over lt/itemgt
• lt/one-ofgt
• lt/rulegt
• lt/grammargt
• lt/linkgt
• lt/vxmlgt

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logon.vxml

• ltfield name"pin" type"digits" gt
• ltpromptgtwhat is your four digit pinlt/promptgt
• lt/fieldgt
• ltblockgt
• ltassign name"application.user_pin" expr"pin" /gt
• ltgoto next"main.vxml" /gt
• lt/blockgt
• lt/formgt
• lt/vxmlgt

21
Retrieving the value

• The value stored as an application level variable
  can be retrieved as follows
• ltprompt version"1.0"gt
• Your pin is
• ltsay-as interpret-as"vxmldigits"gt
• ltvalue expr"application.user_pin"/gt lt/say-asgt
• The prompt demonstrates that the value of
  user-pin is available to each leaf document
  that references root.vxml

22
More on Navigation

• Transition to other forms etc when the FIA has
  processed a form (dialog)
• ltchoicegt - Used within the ltmenugt element to
  select and transition to another dialog.
• ltgotogt - Used within ltblockgt, ltcatchgt, lterrorgt,
  ltfilledgt, ltforeachgt, lthelpgt, ltifgt, ltnoinputgt,
  ltnomatchgt, and ltpromptgt
• ltlinkgt - Used within ltfieldgt, ltformgt, ltinitialgt,
  and ltvxmlgt
• ltsubmitgt Used within ltblockgt, ltcatchgt, lterrorgt,
  ltfilledgt, ltforeachgt, lthelpgt, ltifgt, ltnoinputgt,
  ltnomatchgt, and ltpromptgt 

23
Attributes for navigation

• Specifying the target item
• next - A URI reference e.g.
• next"http//myexamples.com/student_system
  (absolute reference)
• nextstudents.vxml (relative e.g. in same
  directory)
• nextstudents.vxml first_query" (specifies
  dialog within the document)
• nextitem - The name of an input item within the
  same form e.g. nextitem student_name
• expr - A URI reference that is dynamically
  determined by evaluating the ECMAScript
  expression e.g.
• exprstudent_system' '' first_query'
• expritem - The name of an input item within the
  same form

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ltgotogt ltsubmitgt

• ltgotogt
• transition to another form item within current
  form, another form within current document, or
  another document
• transitioning to another dialog or document using
  ltgotogt will cause the old dialogs variables to
  be lost. If the variables are to persist across
  multiple documents, they should be stored with
  application scope
• ltsubmitgt
• used to submit values to the document server via
  an HTTP GET or POST request
• namelist attribute specifies which values are
  being submitted e.g. ltsubmit nexthttpwww.myser
  ver.com/getstudentdetails.jsp namelist
  studentname coursename /gt
• Control will not necessarily return to the
  calling document. For example, the script
  specified in the next attribute might generate
  a VoiceXML document dynamically and execution
  will continue with this document.

25
ltexitgt

• ltexitgt
• terminates all loaded documents and returns
  control to the voice browser which determines
  what to do next
• Attributes
• exprECMAScript expression that is evaluated as
  the return value
• namelistList of variable names to be returned
• ltexitgt example
• ltfilledgtltsubmit namelist source target
  amount" /gt ltexit/gt lt/filledgt   

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ltdisconnectgt

• Causes the voice browser to disconnect
• ltdisconnectgt example
• ltfilledgtltsubmit namelist source target
  amount" /gt ltdisconnect/gt lt/filledgt   
• Note Before ending the session, developers can
  catch the ltdisconnectgt event to perform some
  post-disconnect processing such as submitting any
  remaining data to a Web server.

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lttransfergt (1)

• Enables the user to connect via the telephone to
  another voice application on another speech
  server.
• Also enables the user to connect to a person's
  telephone. Frequently this will be an operator or
  help agent that assists a user having trouble.
• blind transfer
• the caller can converse only with the party on
  the other end of the connection.
• bridge transfer
• the caller may converse with another party and
  also hear prompts and respond by speaking or
  pressing the keys on a touchtone telephone.  This
  enables the caller to proactively end the
  transferred call.  

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lttransfergt (2)

• When the transfer is complete, the connection is
  broken. 
• Once the transfer disconnects, the instructions
  in the ltfilledgt element associated with the
  lttransfergt element are interpreted.   
• The input-form-item variable may contain values
  including the following which indicate why the
  transfer was not successful
• busy - The other person was busy.
• noanswer - The other person did not answer.
• network_busy - An intermediate network was not
  able to transfer the call.
• Various shadow variables contain information
  about a successful transfer e.g..
• duration of the call transfer in seconds. 
• mode used by the caller to terminate the
  transferred call (voice or DTMF

29
ltsubdialoggt

• Enables frequently used code to be saved in a
  library and re-used in several applications
• When invoked, a subdialog executes in a new
  execution environment it does not inherit any
  parameters from the calling dialog.  The
  subdialog proceeds until it encounters  
• ltreturngt elementEnds the execution of a
  subdialog and returns control and data to the
  calling dialog.  Data is returned to the calling
  dialog as a namelist.  When the subdialog
  returns, its execution environment is deleted.
• ltexitgt elementExecution stops
• No form items remain eligible for the FIA to
  select - Execution stops

30
Go to subdialog to elicit name which is
returned to main dialog for greeting
ltsubdialoggt 1

• 3. ltform id"main_menu"gt
• 4. ltblockgt
• 5. Welcome to the Student System Main Menu
• 6 lt/blockgt
• 7 ltsubdialog name"result" src"validation"gt
• 8 lt/subdialoggt
• 9 ltblockgt
• 10 ltpromptgt
• 11 hello ltvalue expr "result.username" /gt
• 12 lt/promptgt
• 13 lt/blockgt
• 14 lt/formgt

• 15 lt!-- subdialog --gt
• 16 ltform id"validation"gt
• 17 ltfield name"username"gt
• 18 ltgrammargt
• 19 liz margaret mike guest
• 20 lt/grammargt
• 21 ltpromptgt Please say your user name. lt/promptgt
• 22 lt/fieldgt
• 23 ltfilledgt
• 24 ltreturn namelist"username" /gt
• 25 lt/filledgt
• 26 lt/formgt

studentsystem3a.vxml
31
Pass value into subdialog for validation
ltsubdialoggt 2
ltform id"main_menu"gt ltblockgtWelcome
lt/blockgt ltfield namestudentnamegt ltgrammargt
john david rosemary jennifer
lt/grammargt ltpromptgt Please say your user name
lt/prompt lt/fieldgt ltsubdialog name"result"
src"validation"gt ltparam name username" expr
studentname" /gt lt/subdialoggt lt/formgt
lt!-- subdialog --gt ltform id"validation"gt ltvar
name username" /gt ltblockgt ltpromptgt hello
ltvalue expr username" /gt lt/promptgt ltreturn
/gt lt/blockgt lt/formgt
studentsystem3b.vxml
32
Pass values in both directions elicit value and
pass to subdialog for validation, return to main
dialog with result
ltsubdialoggt 3
ltform id"main_menu"gt ltblockgtWelcome
lt/blockgt ltfield namestudentnamegt elicit name
lt/fieldgt ltsubdialog name"result"
src"validation"gt ltparam name studentname"
expr username" /gt lt/subdialoggt ltblockgt ltprompt
gt hello ltvalue expr "result.studentname" /gt the
student number is ltvalue expr
"result.studentid" /gt lt/promptgtlt/blockgt lt/formgt
lt!-- subdialog --gt ltform id"validation"gt ltvar
name studentname" /gt ltvar name "studentid"
expr" /gt ltblockgt ltif cond "name'john'"gt lta
ssign name "studentid" expr "'96050918'"
/gt lt/ifgt ltreturn namelist "studentid"
/gt lt/blockgt lt/formgt
studentsystem3c.vxml
33
Tutorial Exercises Using a root document

1. Assuming that you have separate documents for the
   main elements of the Student System - student
   details, course details, view student details,
   reports, and a main menu document - create a root
   document with links to these documents. Provide a
   link in the root document that will enable the
   user to navigate to the main menu document from
   any other document in the application.
2. Create a variable with application scope in the
   root document to hold the user's pin. Elicit a
   value for the user's pin in a file such as
   logon.vxml, store the value in the root document
   and access it from some other child document.

34
Tutorial Exercises Subdialog (1)

• Passing values back from a subdialog following
  some computation within the subdialog
• Load and run the file studentsystem3a.vxml. You
  can say one of the student names (john, david,
  rosemary or jennifer) in response to the system
  prompt.
• Passing values into a subdialog to be referenced
  in that subdialog
• Load and run the file studentsystem3b.vxml. As
  before, you can say one of the student names
  (John, David, Rosemary, Jennifer) in response to
  the system prompt.

35
Tutorial Exercises Subdialog (1)

• Passing values in both directions
• Load and run the file studentsystem3c.vxml. This
  time you have to say the student name 'John' for
  the conditional statement in the subdialog to
  evaluate correctly.
• 6. Add further conditions in the subdialog for
  the names 'David' and 'Rosemary'.
• Amend the code in the main dialog so that if the
  user says the name 'Jennifer', the system
  responds 'Sorry that student is not listed in the
  database'.
• Note Names that are not in the database will
  still have to be included in the recognition
  vocabulary to be recognised and passed on to the
  subdialog.