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Avatar gRPC API usage

In this guide, you will learn how to use the Avatar gRPC API that enables a client and an Avatar chatbot to communicate transparently. Eventually, you will create a simple CLI app to chat with your avatar.

Find the GitHub repo here.

Info

Based on the code from this guide, you can automate communication between avatars and third-party messengers, such as Telegram, Whatsapp, etc. This way you get your Node JS (or some other) server up and running and connect two streams: one from your avatar via gRPC and one from a third-party messenger.

Before launching the CLI app, let’s see how it works from the inside.

Proto files

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Find the proto files in the proto folder of our repo. They are used to automatically generate data access classes, connect to the avatar backend and start chatting.

  • auth.proto is the auth protocol; it presents functions for logging in and creating a token to communicate with an avatar.
  • api.proto is the avatar communication protocol. It presents a two-way stream: a user of the node application sends text messages to the avatar, and the avatar responses come back to them:
service Avatar {
  rpc Conversation(stream UserUtterance) returns (stream AvatarResponse) {}
}

Authorization

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In the auth.js file, you can find the getAuthToken method in which you pass your account ID and API key to log in. This method returns sessionToken and grpcEndpoint (avatar’s endpoint):

​​async function getAuthToken(apiKey, accountId) {
  const {statusCode, headers, trailers, body} = await request(`https://api.voximplant.com/platform_api/Logon?account_id=${accountId}&api_key=${apiKey}`);
  const {result, account_id, nlu_addresses} = await body.json();
  const avatarHttpUrl = new URL(nlu_addresses[0]);
  const avatarGrpcEndpoint = avatarHttpUrl.host + ':443';
  return {grpcEndpoint: avatarGrpcEndpoint, sessionToken: result}
}

In the grpcClient.js file, you get a JSON web token. Connect to the authorization service and call the Login method with the sessionToken and grpcEndpoint you just got. Then, create a gRPC connection (communication stream) by calling clientApi.Conversation(metadata):

clientAuth.Login({account_id: accountId.toString(), session_id: sessionToken}, (error, response) => {
      if (error) throw error
      const authToken = response.jwt_token;

      const clientApi = new AvatarApi(
        grpcEndpoint,
        grpc.credentials.createSsl()
      );

      let metadata = new grpc.Metadata();
      metadata.add('Authorization', 'Bearer ' + authToken);
      metadata.add('avatarId', avatarId);
      resolve(clientApi.Conversation(metadata));
    });

The stream will be used in the main index.js file to subscribe to stream events and upload data. Let us see how.

Conversation

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You call the getAuthToken to get sessionToken and grpcEndpoint, then create Conversation – a gRPC object. This object is for a communication stream, where you can subscribe to different events:

  • Messages in the stream:
​​conversation.on('data', (response) => {
    console.log(`MESSAGE FROM AVATAR: ${response.utterance}`);
  });
  • Errors:

  conversation.on('error', (err) => {
    console.log(err);
  });
  • End of the stream:

  conversation.on('end',() => {
    console.log('AVATAR HAS FINISHED CONVERSATION');
    process.exit(0);
  });

Wait for text input from the console, and when stdin returns a message, upload the object to the stream:

 process.stdin.resume();
 process.stdin.setEncoding('utf8');
 process.stdin.on('data', (userUtteranceText) => {
   conversation.write({text: userUtteranceText})
 });

Instead of stdin here, you can write appropriate code to connect with a third-party messenger.

Test

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Env variables

To run the application, you need:

Put these values into env variables this way in the terminal:

export API_KEY=00000000-0000-0000-0000-0000000001
export ACCOUNT_ID=0000000
export AVATAR_ID=00000000-0000-0000-0000-0000000001

The values are processed in the index.js file that demonstrates Avatar logic.

Launch

To start the conversation, run these commands in the terminal:

npm i
npm run client

A chat with your avatar will look like this:

Chat with your avatar

See also

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