Migrate existing Virtual Assistant to not use Chitchat in Dispatch

Explains the steps to migrate an existing VA to remove Chitchat from Dispatch

Remove Chitchat intent from Dispatch

As part of the default deployment, the Virtual Assistant template creates two LUIS apps: one called <NameofBot><LangLocale>_Dispatch and the other <NameOfBot><LangLocale>_General, along with 2 QnA Knowledge Bases (KBs) for replying to Chitchat and Faq requests. The Chitchat KB in particular can be large and is used to provide a personality to the bot.

The Dispatch LUIS App is used to determine if a user utterance has a General, Skill or Chitchat intent. Once the intent is recognized, the user utterance is routed to the specific LUIS or QnA Kb to fetch a more specific response for the user.

This architecture works well if there are relatively similar numbers of training samples per intent (i.e. if the dataset is balanced). However, our Chitchat personality dataset tends to be very large relative to the other datasets. Once a dataset becomes imbalanced relative to the others, LUIS has a tendency to overfit the user utterance to that intent 1.

To combat the issue of overfitting on Chitchat, we have removed the Chitchat intent from the Dispatch Luis App and only route to the Chitchat KB in the event that there are no other matches. In v1.0, this is the default behavior.

This guide shows you how to remove the Chitchat intent from the Dispatch app if you are migrating from an earlier version of the Virtual Assistant Template. In v1.0, this is the default behavior and nothing needs to be done.



  1. In the Dialogs folder of your Virtual Assistant Project, add this new function to MainDialog.cs:
         /// <summary>
         /// A simple set of heuristics to govern if we should invoke the personality <see cref="QnAMakerDialog"/>.
         /// </summary>
         /// <param name="stepContext">Current dialog context.</param>
         /// <param name="dispatchIntent">Intent that Dispatch thinks should be invoked.</param>
         /// <param name="dispatchScore">Confidence score for intent.</param>
         /// <param name="threshold">User provided threshold between 0.0 and 1.0, if above this threshold do NOT show chitchat.</param>
         /// <returns>A <see cref="bool"/> indicating if we should invoke the personality dialog.</returns>
         private bool ShouldBeginChitChatDialog(WaterfallStepContext stepContext, DispatchLuis.Intent dispatchIntent, double dispatchScore, double threshold = 0.5)
             if (threshold < 0.0 || threshold > 1.0)
                 throw new ArgumentOutOfRangeException(nameof(threshold));
             if (dispatchIntent == DispatchLuis.Intent.None)
                 return true;
             if (dispatchIntent == DispatchLuis.Intent.l_General)
                 // If dispatch classifies user query as general, we should check against the cached general Luis score instead.
                 var generalResult = stepContext.Context.TurnState.Get<GeneralLuis>(StateProperties.GeneralResult);
                 if (generalResult != null)
                     (var _, var generalScore) = generalResult.TopIntent();
                     return generalScore < threshold;
             else if (dispatchScore < threshold)
                 return true;
             return false;
  2. In the RouteStepAsync method in MainDialog.cs, look for the line that says:
     if (dispatchIntent == DispatchLuis.Intent.q_Chitchat)

    and replace this with the newly added method:

     if (ShouldBeginChitChatDialog(stepContext, dispatchIntent, dispatchScore))
  3. deploy-cognitive-models.ps1 and update-cognitive-models.ps1 must be updated to prevent the ChitChat kb from being added to Dispatch. Look for sections that call the dispatch add tool with --type "qna":
         if ($dispatch) {
             Write-Host "> Adding $($langCode) $($kb.id) kb to dispatch file ..." -NoNewline
             dispatch add `
                 --type "qna" `
                 --name $kb.name `
                 --id $kb.kbId  `
                 --key $kb.subscriptionKey `
                 --intentName "q_$($kb.id)" `
                 --dispatch $dispatchFile `
                 --dataFolder $(Join-Path $dispatchFolder $langCode) 2>> $logFile | Out-Null
             Write-Host "Done." -ForegroundColor Green

    and change the conditions to prevent the Chitchat data from being added to dispatch e.g.:

     if ($dispatch -and -not @("Chitchat").Contains($kb.id)) {
  4. Run update-cognitive-models.ps1. Log in to luis.ai, and inspect your Dispatch app. The Chitchat intent should not be present. The file services/DispatchLuis.cs should also have been automatically updated when update-cognitive-models.ps1 ran bf luis:generate:cs as one of the script steps.
         if ($useLuisGen) {
             # Update dispatch.cs file
             Write-Host "> Running LuisGen for Dispatch app..." -NoNewline
             bf luis:generate:cs `
                 --in $(Join-Path $dispatchFolder $langCode "$($dispatch.name).json") `
                 --className "DispatchLuis" `
                 --out $lgOutFolder `
                 --force 2>> $logFile | Out-Null 
             Write-Host "Done." -ForegroundColor Green

    This updates the services/DispatchLuis.cs Intent enum to not include Chitchat anymore.

  5. Please see Pull Request #3291 for more details


  1. Please see Pull Request 3304 for more details