An Opinionated Message Queue with an emitter-style API
npm install mqemitter!ci
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An Opinionated Message Queue with an emitter-style API, but with callbacks.
If you need a multi process MQEmitter, check out the table below:
- [mqemitter-redis]: Redis-powered mqemitter
- [mqemitter-mongodb]: Mongodb based mqemitter
- [mqemitter-child-process]: Share the same mqemitter between a hierarchy of child processes
- [mqemitter-cs]: Expose a MQEmitter via a simple client/server protocol
- [mqemitter-p2p]: A P2P implementation of MQEmitter, based on HyperEmitter and a Merkle DAG
- [mqemitter-aerospike]: Aerospike mqemitter
``sh`
npm install mqemitter
`js
const mq = require('mqemitter')
const emitter = mq({ concurrency: 5 })
const message
emitter.on('hello world', function (message, cb) {
// call callback when you are done
// do not pass any errors, the emitter cannot handle it.
cb()
})
// topic is mandatory
message = { topic: 'hello world', payload: 'or any other fields' }
emitter.emit(message, function () {
// emitter will never return an error
})
`
- [new MQEmitter ([options])](#new-mqemitter-options)
- emitter.emit (message, callback)
- [emitter.on (topic, listener, [callback])](#emitteron-topic-listener-callback)
- [emitter.removeListener (topic, listener, [callback])](#emitterremovelistener-topic-listener-callback)
- emitter.close (callback)
- options
Create a new MQEmitter class.
MQEmitter is the class and function exposed by this module.
It can be created by MQEmitter() or using new MQEmitter().
For more information on wildcards, see this explanation or Qlobber.
- message
- callback (error) => void
- error null
Emit the given message, which must have a topic property, which can contain wildcards as defined on creation.
- topic
- listener (message, done) => void
- callback () => void
Add the given listener to the passed topic. Topic can contain wildcards, as defined on creation.
The listener __must never error__ and done must not be called with an __err__ object.
callback will be called when the event subscribe is done correctly.
The inverse of on.
- callback () => void
Close the given emitter. After, all writes will return an error.
__MQEmitter__ supports the use of wildcards: every topic is splitted according to separator.
The wildcard character + matches exactly _non-empty_ one word:
``js
const mq = require('mqemitter')
const emitter = mq()
emitter.on('hello/+/world', function(message, cb) {
// will ONLY capture { topic: 'hello/my/world', 'something': 'more' }
console.log(message)
cb()
})
emitter.on('hello/+', function(message, cb) {
// will not be called
console.log(message)
cb()
})
emitter.emit({ topic: 'hello/my/world', something: 'more' })
emitter.emit({ topic: 'hello//world', something: 'more' })
`
The wildcard character + matches one word:
`js
const mq = require('mqemitter')
const emitter = mq({ matchEmptyLevels: true })
emitter.on('hello/+/world', function(message, cb) {
// will capture { topic: 'hello/my/world', 'something': 'more' }
// and capture { topic: 'hello//world', 'something': 'more' }
console.log(message)
cb()
})
emitter.on('hello/+', function(message, cb) {
// will not be called
console.log(message)
cb()
})
emitter.emit({ topic: 'hello/my/world', something: 'more' })
emitter.emit({ topic: 'hello//world', something: 'more' })
`
The wildcard character # matches zero or more words:
`js
const mq = require('mqemitter')
const emitter = mq()
emitter.on('hello/#', function(message, cb) {
// this will print { topic: 'hello/my/world', 'something': 'more' }
console.log(message)
cb()
})
emitter.on('#', function(message, cb) {
// this will print { topic: 'hello/my/world', 'something': 'more' }
console.log(message)
cb()
})
emitter.on('hello/my/world/#', function(message, cb) {
// this will print { topic: 'hello/my/world', 'something': 'more' }
console.log(message)
cb()
})
emitter.emit({ topic: 'hello/my/world', something: 'more' })
`
Of course, you can mix # and +` in the same subscription.
MIT
[mqemitter-redis]: https://www.npmjs.com/mqemitter-redis
[mqemitter-mongodb]: https://www.npmjs.com/mqemitter-mongodb
[mqemitter-child-process]: https://www.npmjs.com/mqemitter-child-process
[mqemitter-cs]: https://www.npmjs.com/mqemitter-cs
[mqemitter-p2p]: https://www.npmjs.com/mqemitter-p2p
[mqemitter-aerospike]: https://www.npmjs.com/mqemitter-aerospike