TDengine/docs/examples/node/websocketexample/tmq_example.js

const taos = require("@tdengine/websocket");

const db = 'power';
const stable = 'meters';
const topics = ['power_meters_topic'];

// ANCHOR: create_consumer
async function createConsumer() {
    let configMap = new Map([
        [taos.TMQConstants.GROUP_ID, "group1"],
        [taos.TMQConstants.CLIENT_ID, 'client1'],
        [taos.TMQConstants.CONNECT_USER, "root"],
        [taos.TMQConstants.CONNECT_PASS, "taosdata"],
        [taos.TMQConstants.AUTO_OFFSET_RESET, "latest"],
        [taos.TMQConstants.WS_URL, 'ws://localhost:6041'],
        [taos.TMQConstants.ENABLE_AUTO_COMMIT, 'true'],
        [taos.TMQConstants.AUTO_COMMIT_INTERVAL_MS, '1000']
    ]);
    try {
        return await taos.tmqConnect(configMap);
    }catch (err) {
        console.log("Failed to create websocket consumer, ErrCode:" + err.code + "; ErrMessage: " + err.message);
        throw err;
    }
    
}
// ANCHOR_END: create_consumer 

async function prepare() {
    let conf = new taos.WSConfig('ws://localhost:6041');
    conf.setUser('root');
    conf.setPwd('taosdata');
    conf.setDb('power');
    const createDB = `CREATE DATABASE IF NOT EXISTS POWER ${db} KEEP 3650 DURATION 10 BUFFER 16 WAL_LEVEL 1;`;
    const createStable = `CREATE STABLE IF NOT EXISTS ${db}.${stable} (ts timestamp, current float, voltage int, phase float) TAGS (location binary(64), groupId int);`;
    
    let wsSql = await taos.sqlConnect(conf);
    await wsSql.exec(createDB);
    await wsSql.exec(createStable);

    let createTopic = `CREATE TOPIC IF NOT EXISTS ${topics[0]} AS SELECT * FROM ${db}.${stable}`;
    await wsSql.exec(createTopic);


    for (let i = 0; i < 10; i++) {
        await wsSql.exec(`INSERT INTO d1001 USING ${stable} (location, groupId) TAGS ("California.SanFrancisco", 3) VALUES (NOW, ${10 + i}, ${200 + i}, ${0.32 + i})`);
    }
    wsSql.Close();
}

async function subscribe(consumer) {
    // ANCHOR: commit 
    try {
        await consumer.subscribe(['topic_meters']);
        for (let i = 0; i < 50; i++) {
            let res = await consumer.poll(100);
            for (let [key, value] of res) {
                console.log(key, value);
            }
            consumer.commit();
        }        
    } catch (err) {
        console.error("Failed to poll data; err.code, ErrCode:" + err.code + "; ErrMessage: " + err.message);
        throw err;
    }
    // ANCHOR_END: commit
}

async function test() {
    // ANCHOR: unsubscribe
    let consumer = null;
    try {
        await prepare();
        let consumer = await createConsumer()
        await subscribe(consumer)      
        await consumer.unsubscribe();
    }
    catch (err) {
        console.error("Failed to unsubscribe consume, ErrCode:" + err.code + "; ErrMessage: " + err.message);
    }
    finally {
        if (consumer) {
            await consumer.close();
        }
        taos.destroy();
    }
    // ANCHOR_END: unsubscribe
}

test()