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Realtime DB Updates Example

This tutorial is about using Macrometa GDN as a realtime database with local latencies across the globe.

Prerequisites​

  • A Macrometa account with sufficient permissions to create streams.
  • An API key. For more information, refer to Create API Keys.
  • Appropriate SDK installed. For more information, refer to Install SDKs.

Realtime Updates Code​

const jsc8 = require("jsc8");

// Constants - DB
const globalUrl = "https://play.paas.macrometa.io/";
const email = "your@email.com";
const password = "password";
const client = new jsc8(globalUrl);

// Variables
const collectionName = "ddos";
let listener;
const data = [
  { ip: "10.1.1.1", action: "block", rule: "blocklistA" },
  { ip: "20.1.1.2", action: "block", rule: "blocklistA" },
  { ip: "30.1.1.3", action: "block", rule: "blocklistB" },
  { ip: "40.1.1.4", action: "block", rule: "blocklistA" },
  { ip: "50.1.1.5", action: "block", rule: "blocklistB" }
];

const sleep = (milliseconds) => {
  return new Promise(resolve => setTimeout(resolve, milliseconds));
};

// Create an authenticated instance with a token or API key

// const client = new jsc8({url: globalUrl, token: "XXXX", fabricName: '_system'});
// const client = new jsc8({url: globalUrl, apiKey: "XXXX", fabricName: '_system'});

// Or use email and password to authenticate client instance

async function createCollection () {
  console.log("\n1. Log in.");
  await client.login(email, password);
  console.log("\n2. Create collection.");
  try {
    console.log(`Creating the collection ${collectionName}...`);
    const existsColl = await client.hasCollection(collectionName);
    if (existsColl === false) {
      await client.createCollection(collectionName, { stream: true });
    }
    // Add an onChange listener for collection
    listener = await client.onCollectionChange(collectionName);
    
    // Decode the message printed here in readable format
    listener.on("message", (msg) => {
      const receivedMsg = msg && JSON.parse(msg);
      console.log("message=>", Buffer.from(receivedMsg.payload, "base64").toString("ascii"))
    });
    listener.on("open", () => console.log("Connection open"));
    listener.on("close", () => console.log("Connection closed"));
  } catch (e) {
    await console.log("Collection creation did not succeed due to " + e);
  }
}
async function insertData () {
  console.log(`\n3. Insert data in region ${globalUrl}`);
  await client.insertDocumentMany(collectionName, data);
}
async function deleteData () {
  console.log("\n4. Delete data");
  await client.deleteCollection(collectionName);
}
(async function () {
  await createCollection();
  await sleep(2000);
  await insertData();
  await sleep(10000);
  await listener.close();
  await deleteData();
})();