Node.js Message Queue and Multi-Process Manager
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ewd-qoper8: High-performance Node.js Message Queue

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Rob Tweed
24 February 2016, M/Gateway Developments Ltd

Twitter: @rtweed

Google Group for discussions, support, advice etc:

Thanks to Alexey Kucherenko for development of unit and integration tests, with support from the Ripple Foundation.

What is ewd-qoper8?

ewd-qoper8 is a generic, high-performance Node.js-based message queue module. It provides you with:

  • a memory-based queue within your main process onto which you can add JSON messages
  • a pool of persistent child processes (aka worker processes) that run your message handler functions
  • a worker process pool manager that will start up and shut down worker processes based on demand
  • a dispatcher that processes the queue whenever a message is added to it, and attempts to send the message to an available worker process

It differs from most other message queues by preventing a worker process from handling more than one message at a time. This is by deliberate design.

You determine the maximum size of the worker process pool. If no free worker processes are available, messages will remain on the queue. The queue is automatically processed whenever:

  • a new message is added to the queue
  • a worker process completes its processing of a message and returns itself to the available pool

The structure of messages is entirely up to you, but:

  • they are JavaScript objects
  • they should always have a type property

How messages are handled within a worker process is up to you. You define a handler method/function for each message type you expect to be added to the queue.

ewd-qoper8 is highly customisable. For example, the master and/or worker processes can be customised to connect to any database you wish, and it can be integrated with a Node.js-based web-server module such as Express, and with a web-socket module such as You can also over-ride the memory-based queue and implement your own persistent one.


   npm install ewd-qoper8

Using ewd-qoper8

Full details and documentation can be found in the Guide file or at


Copyright (c) 2016 M/Gateway Developments Ltd,
Reigate, Surrey UK.
All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at                           

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and
limitations under the License.