MQTT_LexClient_mqtt.js

class Mqtt {
    
    constructor() { 
        this.device = undefined;
    }

    async _getCredentials() {
        AWS.config.region = this.region;
        var cognitoidentity = new AWS.CognitoIdentity();
        var params = {
            IdentityPoolId: this.poolId
        };
        const identityId = await cognitoidentity.getId(params).promise();
        const data = await cognitoidentity.getCredentialsForIdentity(identityId).promise();
        var credentials = {
            accessKey: data.Credentials.AccessKeyId,
            secretKey: data.Credentials.SecretKey,
            sessionToken: data.Credentials.SessionToken
        };
        return credentials;
    }

    async init(poolId, region, endpoint, topic, clientId) {
        this.poolId = poolId;
        this.region = region;
        this.endpoint = endpoint;
        this.topic = topic;
        this.clientId = clientId;

        let self = this;

        const credentials = await this._getCredentials(); // Credentialsの取得
    
        const awsIot = require('aws-iot-device-sdk');
        this.device = awsIot.device({
            region: this.region,
            clientId: this.clientId,
            accessKeyId: credentials.accessKey,
            secretKey: credentials.secretKey,
            sessionToken : credentials.sessionToken,
            protocol: 'wss',
            port: 443,
            host: this.endpoint
        });
    
        this.device.on('message', function(_topic, payload) {
            self.onRecive(payload.toString("utf-8"));
        });
    
        this.device.subscribe(topic, undefined, (err, granted) => {
            if( err ) {
                console.log('subscribe error: ' + err);
            }
        });
    }

    async Send(param) {
        await this.device.publish(this.topic, JSON.stringify(param), err => {
            if( err ){
                console.log('publish error: ' + err);
            }
        });
    }
}