aedes-cached-persistence




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

- aedes-cached-persistence
- Install
- Provided methods
- Implement another persistence
- Inheritance
- Tests
- License

Install

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

``sh
npm install aedes-cached-persistence --save
`

Provided methods

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

Implement another persistence

$3

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

`js
const CachedPersistence = require('aedes-cached-persistence')

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

class MyPersistence extends CachedPersistence {
constructor(opts) {
super(opts)
}
addSubscriptions(client, subs, cb) {
// ..persistence specific implementation..
// call super._addedSubscriptions when you are done
super._addedSubscriptions(client, subs.map(mapSub), cb)
}
removeSubscriptions(client, subs, cb) {
// ..persistence specific implementation..
// call super._removedSubscriptions when you are done
super._removedSubscriptions(client, subs.map(mapSub), cb)
}
}

function mapSub (sub) {
return { topic: sub.topic }
}
`

$3

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

`js
const test = require('node:test')
const myperst = require('./')
const abs = require('aedes-cached-persistence/abstract')

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

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

`js
const test = require('node:test')
const myperst = require('./')
const abs = require('aedes-persistence/abstract')
const clean = require('./clean') // invented module

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

License

MIT

[aedes]: http://npmjs.com/package/aedes
[aedes-persistence]: http://npmjs.com/package/aedes-persistence