Use the SDK's CLI init component command to create a JavaScript or TypeScript file with the framework for working with the Oracle Digital Assistant Node.js SDK to write a custom component. The language that you specified when you ran the init command to create the component package determines whether a JavaScript or a TypeScript file is created.

bots-node-sdk init component <component name> c components

Your custom component must export two objects:

• metadata: This provides the following component information to the skill.
  • Component name
  • Supported properties
  • Supported transition actions

  For YAML-based dialog flows, the custom component supports the following properties by default. These properties aren't available for skills designed in Visual dialog mode.

  • autoNumberPostbackActions: Boolean. Not required. When true, buttons and list options are numbered automatically. The default is false. See Auto-Numbering for Text-Only Channels in YAML Dialog Flows.
  • insightsEndConversation: Boolean. Not required. When true, the session stops recording the conversation for insights reporting. The default is false. See Model the Dialog Flow.
  • insightsInclude: Boolean. Not required. When true, the state is included in insights reporting. The default is true. See Model the Dialog Flow.
  • translate: Boolean. Not required. When true, autotranslation is enabled for this component. The default is the value of the autotranslation context variable. See Translation Services in Skills.
• invoke: This contains the logic to execute. In this method, you can read and write skill context variables, create conversation messages, set state transitions, make REST calls, and more. Typically, you would use the async keyword with this function to handle promises. The invoke function takes the following argument:
  • context, which names the reference to the CustomComponentContext object in the Digital Assistant Node.js SDK. This class is described in the SDK documentation at https://oracle.github.io/bots-node-sdk/. In earlier versions of the SDK, the name was conversation. You can use either name.
  Note
  
  If you are using a JavaScript library that doesn't support promises (and thus aren't using async keyword), it is also possible to add a done argument as a callback that the component invokes when it has finished processing.

Here’s an example:

'use strict';

module.exports = {

  metadata: {
    name: 'helloWorld',
    properties: {
      human: { required: true, type: 'string' }
    },
    supportedActions: ['weekday', 'weekend']
  },

  invoke: async(context) => {
    // Retrieve the value of the 'human' component property.
    const { human } = context.properties();
    // determine date
    const now = new Date();
    const dayOfWeek = now.toLocaleDateString('en-US', { weekday: 'long' });
    const isWeekend = [0, 6].indexOf(now.getDay()) > -1;
    // Send two messages, and transition based on the day of the week
    context.reply(`Greetings ${human}`)
      .reply(`Today is ${now.toLocaleDateString()}, a ${dayOfWeek}`)
      .transition(isWeekend ? 'weekend' : 'weekday');   
  }
}

To learn more and explore some code examples, see Writing Custom Components in the Bots Node SDK documentation.

You use different combinations of the Bots Node SDK keepTurn and transition functions to define how the custom component interacts with a user and how the conversation continues after the component returns flow control to the skill.

• keepTurn(boolean) specifies whether the conversation should transition to another state without first prompting for user input.

  Note that if you want to set keepTurn to true, you should call keepTurn after you call reply because reply implicitly sets keepTurn to false.

• transition(action) causes the dialog to transition to the next state after all replies, if any, are sent. The optional action argument names that action (outcome) that the component returns.

  If you don't call transition(), the response is sent but the dialog stays in the state and subsequent user input comes back to this component. That is, invoke() is called again.

invoke: async (context) ==> {
   ...
   context.reply(payload);
   context.keepTurn(true);
   context.transition ("success"); 
}

Here are some common use cases where you would use keepTurn and transition to control the dialog flow:

invoke: async (context) => {
    const listVariableName = context.properties().variableName;
    ...
    // Write list of options to a context variable
    context.variable(listVariableName, list);
   // Navigate to next state without 
   // first prompting for user interaction.
   context.keepTurn(true);
   context.transition();
 }

context.keepTurn(false);
context.transition("success");

  invoke: async (context) => {
    // Perform conversation tasks.
    const tracking_token = "a2VlcHR1cm4gZXhhbXBsZQ==";    
    const quotes = require("./json/Quotes.json");
    const quote = quotes[Math.floor(Math.random() * quotes.length)];
    
    // Check if postback action is issued. If postback action is issued, 
    // check if postback is from this component rendering. This ensures
    // that the component only responds to its own postback actions.     
    if (context.postback() && context.postback().token == tracking_token && context.postback().isNo) {
      context.keepTurn(true);
      context.transition();
    } else {
      // Show the quote of the day.
      context.reply("'" + quote.quote + "'");
      context.reply(" Quote by: " + quote.origin);
      // Create a single message with two buttons to 
      // request another quote or not.
      const mf = context.getMessageFactory();
      const message = mf.createTextMessage('Do you want another quote?')
        .addAction(mf.createPostbackAction('Yes', { isNo: false, token: tracking_token }))
        .addAction(mf.createPostbackAction('No', { isNo: true, token: tracking_token })); 
      context.reply(message);
      // Although reply() automatically sets keepTurn to false, 
      // it's good practice to explicitly set it so that it's
      // easier to see how you intend the component to behave.
      context.keepTurn(false);
    };
  }

invoke: async (context) => {

  const quotes = require("./json/Quotes.json");
  const quote = quotes[Math.floor(Math.random() * quotes.length)];
  
  // Check if postback action is issued and postback is from this component rendering. 
  // This ensures that the component only responds to its own postback actions.     
  const um = context.getUserMessage()
  if (um instanceof PostbackMessage && um.getPostback() && um.getPostback()['system.state'] === context.getRequest().state && um.getPostback().isNo) {
    context.keepTurn(true);
    context.transition();
  } else {
    // Show the quote of the day.
    context.reply(`'${quote.quote}'`);
    context.reply(`Quote by: ${quote.origin}`);
    // Create a single message with two buttons to request another quote or not.
    let actions = [];

    const mf = context.getMessageFactory();
    const message = mf.createTextMessage('Do you want another quote?')
      .addAction(mf.createPostbackAction('Yes', { isNo: false }))
      .addAction(mf.createPostbackAction('No', { isNo: true }));
    context.reply(message);
    // Although reply() automatically sets keepTurn to false, it's good practice to explicitly set it so that it's
    // easier to see how you intend the component to behave.
    context.keepTurn(false);
  }
}

You use CustomComponentContext instance methods to get the context for the invocation, access and change variables, and send results back to the dialog engine.

You can find several code examples for using these methods in Writing Custom Components and Conversation Messaging in the Bots Node SDK documentation

The SDK reference documentation is at https://github.com/oracle/bots-node-sdk.

When you design a custom component, you should consider whether the component will be used by a skill that supports more than one language.

If the custom component must support multi-language skills, then you need to know if the skills are configured for native language support or translation service.

When you use a translation service, you can translate the text from the skill. You have these options:

• Set the translate property in the custom component's state to true to translate the component's reply, as described in Send Responses Directly to the Translation Service.

• Send raw data back to the skill in variables and use the variables' values in a system component that composes the output. Set that component's translate property to true. See Use a System Component to Pass the Message to the Translation Service.

• Send raw data back to the skill in variables and use the variables' values in a system component that uses the resource bundle key for the language. See Use a System Component to Reference a Resource Bundle.

For native language skills, you have these options:

• Pass the data back to the skill in variables and then output the text from a system component by passing the variables' values to a resource bundle key, as described in Use a System Component to Reference a Resource Bundle. With this option, the custom component must have metadata properties for the skill to pass the names of the variables to store the data in.

• Use the resource bundle from the custom component to compose the custom component's reply, as described in Reference Resource Bundles from the Custom Component. You use the conversation.translate() method to get the resource bundle string to use for your call to context.reply(). This option is only valid for resource bundle definitions that use positional (numbered) parameters. It doesn't work for named parameters. With this option, the custom component must have a metadata property for name of the resource bundle key, and the named resource bundle key's parameters must match those used in the call to context.reply().

Here's an example of using the resource bundle from the custom component. In this example, fmTemplate would be set to something like ${rb('date.dayOfWeekMessage', 'lundi', '19 juillet 2021')}.

'use strict';

var IntlPolyfill    = require('intl');
Intl.DateTimeFormat = IntlPolyfill.DateTimeFormat;

module.exports = {
  metadata: () => ({
    name: 'Date.DayOfWeek',
    properties: {
      rbKey:   { required: true,  type: 'string'    }
    },
    supportedActions: []
  }),
  invoke: (context, done) => {
    const { rbKey } = context.properties();
    if (!rbKey || rbKey.startsWith('${')){
      context.transition();
            done(new Error('The state is missing the rbKey property or it uses an invalid expression to pass the value.'));
    }
    //detect user locale. If not set, define a default
    const locale  = context.getVariable('profile.locale') ? 
      context.getVariable('profile.locale') : 'en-AU';  
    const jsLocale     = locale.replace('_','-');
    //when profile languageTag is set, use it. If not, use profile.locale
    const languageTag = context.getVariable('profile.languageTag')?
                      context.getVariable('profile.languageTag') : jslocale;
   /* =============================================================
      Determine the current date in local format and 
      the day name for the locale
      ============================================================= */
    var now          = new Date();
    var dayTemplate  = new Intl.DateTimeFormat(languageTag,
      { weekday: 'long' });
    var dayOfWeek    = dayTemplate.format(now);
    var dateTemplate = new Intl.DateTimeFormat(languageTag, 
      { year: 'numeric', month: 'long', day: 'numeric'});
    var dateToday    = dateTemplate.format(now);

   /* =============================================================
      Use the context.translate() method to create the ${Freemarker} 
      template that's evaluated when the reply() is flushed to the 
      client.
      ============================================================= */
    const fmTemplate = context.translate(rbKey, dateToday, dayOfWeek );

    context.reply(fmTemplate)
                .transition()
                .logger().info('INFO : Generated FreeMarker => ' 
                + fmTemplate);
    done();  
  }
};

In a digital assistant conversation, a user can break a conversation flow by changing the subject. For example, if a user starts a flow to make a purchase, they might interrupt that flow to ask how much credit they have on a gift card. We call this a non sequitur. To enable the digital assistant to identify and handle non sequiturs, call the context.invalidInput(payload) method when a user utterance response is not understood in the context of the component.

In a digital conversation, the runtime determines if an invalid input is a non sequitur by searching for response matches in all skills. If it finds matches, it reroutes the flow. If not, it displays the message, if provided, prompts the user for input, and then executes the component again. The new input is passed to the component in the text property.

In a standalone skill conversation, the runtime displays the message, if provided, prompts the user for input, and then executes the component again. The new input is passed to the component in the text property.

This example code calls context.invalidInput(payload) whenever the input doesn’t convert to a number.

"use strict"
 
module.exports = {
 
    metadata: () => ({
        "name": "AgeChecker",
        "properties": {
            "minAge": { "type": "integer", "required": true }
        },
        "supportedActions": [
            "allow",
            "block",
            "unsupportedPayload"
        ]
    }),
 
    invoke: (context, done) => {
        // Parse a number out of the incoming message
        const text = context.text();
        var age = 0;
        if (text){
          const matches = text.match(/\d+/);
          if (matches) {
              age = matches[0];
          } else {
              context.invalidUserInput("Age input not understood. Please try again");
              done();
              return;
          }
        } else {
          context.transition('unsupportedPayload");
          done();
          return;
        }
 
        context.logger().info('AgeChecker: using age=' + age);
 
        // Set action based on age check
        let minAge = context.properties().minAge || 18;
        context.transition( age >= minAge ? 'allow' : 'block' );
 
        done();
    }
};

Here’s an example of how a digital assistant handles invalid input at runtime. For the first age response (twentyfive), there are no matches in any skills registered with the digital assistant so the conversation displays the specified context.invalidUserInput message. In the second age response (send money), the digital assistant finds a match so it asks if it should reroute to that flow.

You should call either context.invalidInput() or context.transition(). If you call both operations, ensure that the system.invalidUserInput variable is still set if any additional message is sent. Also note that user input components (such as Common Response and Resolve Entities components) reset system.invalidUserInput.

Say, for example, that we modify the AgeChecker component as shown below, and call context.transition() after context.invalidInput().

if (matches) {  age = matches[0]; } else { 
      context.invalidUserInput("Age input not understood. Please try again"); 
      context.transition("invalid"); 
      context.keepTurn(true);
      done();
      return;
}

In this case, the data flow needs to transition back to askage so that the user gets two output messages – "Age input not understood. Please try again" followed by "How old are you?". Here's how that might be handled in a YAML-mode dialog flow.

  askage:
    component: "System.Output"
    properties:
      text: "How old are you?"
    transitions:
      next: "checkage"
  checkage:
    component: "AgeChecker"
    properties:
      minAge: 18
    transitions:
      actions:
        allow: "crust"
        block: "underage"
        invalid: "askage"