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(err);
        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);

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

    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();
}

// ANCHOR: subscribe 
async function subscribe(consumer) {
    await consumer.subscribe(topics);
    for (let i = 0; i < 5; i++) {
        let res = await consumer.poll(500);
        for (let [key, value] of res) {
            console.log(key, value);
        }
        if (res.size == 0) {
            break;
        }
        await consumer.commit();
    }
}
// ANCHOR_END: subscribe

async function test() {
    let consumer = null;
    try {
        await prepare();
        let consumer = await createConsumer()
        await subscribe(consumer)
        // ANCHOR: assignment
        let assignment = await consumer.assignment();
        console.log(assignment);

        assignment = await consumer.seekToBeginning(assignment);
        for(let i in assignment) {
            console.log("seek after:", assignment[i])
        }
        // ANCHOR_END: assignment       
        await consumer.unsubscribe();
    }
    catch (err) {
        console.error(err.code, err.message);
    }
    finally {
        if (consumer) {
            await consumer.close();
        }
        taos.destroy();
    }
}

test()