aedes-cached-persistence  

Abstract class to write an Aedes [persistence][persistence] with in-process caching of subscriptions. It implements the API defined by aedes-persistence.

• Install
• Provided methods
• Implement another persistence
• License

Install

To install aedes-cached--persistence, simply use npm:

npm install aedes-cached-persistence --save

Provided methods

• CachedPersistence()
• instance.subscriptionsByTopic()
• instance.cleanSubscriptions()
• instance.destroy()

Implement another persistence

Inheritance

In order to reuse aedes-cached-persistence, you need to:

'use strict'

var util = require('util')
var CachedPersistence = require('aedes-cached-persistence')

// if you need http://npm.im/aedes-packet, it is available
// from this module as well
// var Packet = CachedPersistence.Packet

function MyPersistence (opts) {
  if (!(this instanceof MyPersistence)) {
    return new MyPersistence(opts)
  }
  // initialize your data here

  CachedPersistence.call(this, opts)
}

util.inherits(MyPersistence, CachedPersistence)

MyPersistence.prototype.addSubscriptions = function (client, subs, cb) {
  // ..persistence specific implementation..

  // call this._addedSubscriptions when you are done
  this._addedSubscriptions(client, subsObjs, cb)
}

MyPersistence.prototype.removeSubscriptions = function (client, subs, cb) {
  // ..persistence specific implementation..

  // call this._addedSubscriptions when you are done
  this._removedSubscriptions(client, subs.map(subs, client), cb)
}

function toSubObj (sub) {
  return {
    clientId: this.id,
    topic: sub.topic
  }
}

Tests

A persistence needs to pass all tests defined in ./abstract.js. You can import and use that test suite in the following manner:

var test = require('tape').test
var myperst = require('./')
var abs = require('aedes-cached-persistence/abstract')

abs({
  test: test,
  persistence: myperst
})

If you require some async stuff before returning, a callback is also supported:

var test = require('tape').test
var myperst = require('./')
var abs = require('aedes-persistence/abstract')
var clean = require('./clean') // invented module

abs({
  test: test,
  buildEmitter: require('mymqemitter'), // optional
  persistence: function build (cb) {
    clean(function (err) {
      cb(err, myperst())
    })
  }
})

License

MIT