How to add JSON data to Jetstream strams?

Question

I have a code written in node-nats-streaming and trying to convert it to newer jetstream. A part of code looks like this:

import { Message, Stan } from 'node-nats-streaming';
import { Subjects } from './subjects';


interface Event {
  subject: Subjects;
  data: any;
}

export abstract class Listener<T extends Event> {
  abstract subject: T['subject'];
  abstract queueGroupName: string;
  abstract onMessage(data: T['data'], msg: Message): void;
  private client: Stan;
  protected ackWait = 5 * 1000;

  constructor(client: Stan) {
    this.client = client;
  }

  subscriptionOptions() {
    return this.client
      .subscriptionOptions()
      .setDeliverAllAvailable()
      .setManualAckMode(true)
      .setAckWait(this.ackWait)
      .setDurableName(this.queueGroupName);
  }

  listen() {
    const subscription = this.client.subscribe(
      this.subject,
      this.queueGroupName,
      this.subscriptionOptions()
    );

    subscription.on('message', (msg: Message) => {
      console.log(`Message received: ${this.subject} / ${this.queueGroupName}`);

      const parsedData = this.parseMessage(msg);
      this.onMessage(parsedData, msg);
    });
  }

  parseMessage(msg: Message) {
    const data = msg.getData();
    return typeof data === 'string'
      ? JSON.parse(data)
      : JSON.parse(data.toString('utf8'));
  }
}

As I searched through the documents it seems I can do something like following:

import { connect } from "nats";

const jsm = await nc.jetstreamManager();
const cfg = {
  name: "EVENTS",
  subjects: ["events.>"],
};

await jsm.streams.add(cfg);

But it seems there are only name and subject options available. But from my original code I need a data property it can handle JSON objects. Is there a way I can convert this code to a Jetstream code or I should change the logic of the whole application as well?

How to add JSON data to Jetstream strams?

0 Answers0