Subscriptions

Create a Subscriber to define a message handler for messages that are published on the corresponding topic.

Subscribers are contained in PUBSUB_ROOT_DIR/subscriptions.

tip

Files ending in .sub.js or .sub.ts in PUBSUB_ROOT_DIR/subscriptions will be auto-loaded by the subscription server.

Examples

Typescript subscription example

/pubsub/subscriptions/simple.topic.name.console-log.sub.ts

import { SubscriberObject } from "@honestfoodcompany/pubsub";

import { Payload } from '../topics/test-topic';

export default: SubscriberObject<Payload> = {

topicName: 'simple.topic',

subscriptionName: 'simple.topic.console-log.sub',

description: 'Will console log messages published on test.topic',

handleMessage: function(message): void {

console.log(this.subscriptionName, 'received message');

console.log(message.data.toString());

const payload = message.toJSON();

message.ack();

},

handleError: function(error: Error): void {

// default error handler for subscriber

}

};

Javascript subscription example

/pubsub/subscriptions/simple.topic.name.sub.js

exports.default = {

topicName: 'test.topic',

subscriptionName: 'test.topic.sub',

description: 'Will console log messages published on test.topic',

handleMessage: function (message) {

console.log(this.subscriptionName, 'received message');

console.log(message.data.toString());

message.ack();

},

};

Subscription example with custom subscriber options

"/pubsub/subscriptions/simple.topic.name.subscription.js

exports.default = {

topicName: 'test.topic',

subscriptionName: 'test.topic.subscription',

description: 'Will console log messages published on test.topic',

options: {

flowControl: {

maxMessages: 500, // max messages in progress

},

},

handleMessage: function (message) {

console.log(`received a message on ${this.subscriptionName}`);

console.log(message.data.toString());

message.ack();

},

};

Subscriber Options

See full options available in API Docs.