This project Bull to provide a fan out topic whereby a domain event can be published by the event publisher to a topic. The topic listens to the events which are sent to the topic, where a list of registrations are maintained by the process. The topic then re-emits the event onto the queue for processing.
The simple architecture for this is as follows:
If you want to see what is happening in your Bull instance, use the Bull UI to view the queues.
To run the example:
npm installnf start
In our example, we have an API which emits domain events to a Bull queue called
domain.events. These domain events all have a property called eventName
which is prefixed by domain.events.. Domain events all have individual names,
which extend the prefix (e.g. domain.events.created).
Our topic is a worker process which listens for all events published on the
topic domain.events, so catches all of the domain events which get published
by the publishing process.
When the topic receives an event, it searches through it's list of registrations to see if there are any jobs which are registered against that event. For each job that it finds, it sends a job to a Bull queue for that job.
Worker processes listen for events on their respective queues and process them as they see fit.
In our example we have two workers, an Email sender and an SMS sender. When you run the example, the publisher emits the event on a schedule basis, which is then consumed by the two processes.
This configuration uses up a few connections to a Redis server. The publisher uses 2 x connection, the topic uses 2 x connection for pubsub and 2 x the number of queues you intend to publish to. Each worker process uses 2 x connections to Redis (I think...).
MIT License
Copyright (c) 2017 James Darbyshire [email protected]
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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