rabbit-eventstore

This is an event sourcing CQRS framework for nodejs and rabbitmq. It consists of:

• A server listening to a RabbitMQ queue for event messages. Each event message will get a "position number" (which is an uniqe incremental id) and be appended to a log/storage file. After properly numbered and stored, the event message will be re-published (with the position number) to an AMQP fanout exchange.
• A javascript module for publishing new events. ("The command.")
• A javascript module for fetching events. ("The listener.")

some generic principles

• The event messages must be JSON.

the server

get history over http

To download all events messages, just make an HTTP request to the server! (We don't check HTTP method, path or anything. Just make a request!)

The event messages are JSON blobs separated by line break.

the listener

The listener will fetch historic events from the position you give, and listen to new events. They will come in strict order!

const listener = require('rabbit-eventstore/listener');

// Start fetching events from position 50:
listener.listen(50, msg => {
  console.log('Incoming event:', msg);
});

// Start fetching events from the beginning of time:
listener.listen(0, msg => {
  console.log('Incoming event:', msg);
});

// Just fetch new events (from now on):
listener.listen(msg => {
  console.log('Incoming event:', msg);
});

If you are returning a promise from them listen callback, the next message will not be fetched until you resolve the promise.

environment vars

for the server and the javascript modules

• AMQPHOST - The domain/hostname/ip to connect to. Default is localhost.
• DEBUG - Set to something truthy to output debug messages to stdout.
• EXCHANGENAME - The AMQP exchange to publish to. Default is events.
• QUEUENAME - The AMQP queue to consume. Default is events.

for the server only

• PORT - Listen on this port for http requests. Default is 80.
• STORAGEFILE - The file path to save event messages to. Default is ./storage.

for the consumer javascript module

• HISTORYURL - Url to the http interface of the server (to get historic events). Default is http://localhost/.

roadmap

• Different AMQP servers for the consuming queue and the fanout. (For future scaling.)
• Rotation of the storage file. Maybe pushing old storage files to AWS S3 or such services.