ovcina-rapidriver 2.0.8

RabbitMQ is required to be running: https://www.rabbitmq.com/download.html

Installation

Create a folder for the microservice. Open a terminal window and navigate to the empty folder.

Install rapidriver Node module:

npm install @ovcina/rapidriver

Creating the service

An example can be found in service-example.js

First import the node module:

var rapidriver = require("@ovcina/rapidriver");

Define a constant called 'host':

const host = 'amqp://localhost';

Subscribe to an event on a river:

rapidriver.subscribe(host, [
    {river: "test", event: "display", work: (msg) => {
        console.log(" [*] Received: '%s'", msg); 
    }}
]);

Send an event back to the rapid, and remember to add the "publish" parameter in the callback function:

rapidriver.subscribe(host, [
    {river: "test", event: "display", work: (msg, publish) => {
        publish("error", "Error Message"); 
    }}
]);

Testing the service

Run RabbitMQ message broker:

rabbitmq-server

Run the service:

node service.js

The file "producer.js" is for sending a message to the rapid which the service can subscribe to. It's only used for testing the service:

node path/to/producer.js <event_name> <message>

Open a new terminal window. To test the running service-example.js, run the producer and make a display event:

node node_modules/@ovcina/rapidriver/producer.js "display" "hello world"

It is also possible to publish a message programmatically, without having to subscribe to a river first:

rapidriver.publish(host, event, msg);

Further Testing

Try making a new service (in a different folder), and make it subscribe to the "error" river.

rapidriver.subscribe(host, [
    {river: "monitoring", event: "error", work: (msg) => {
        console.log(" [*] Received: '%s'", msg); 
    }}
]);

In the first service add the "publish(event, msg)" line which sends an error event back into the river. Now when both services are run, make the producer send a display event, the first service will send an error event which the other service will subscribe to and print out.