This package provides support for an event-sourced persistence strategy leveraging node.js's Stream interface.
This exposes the wonderful pipe for reading events into and out of Aggregate roots while making it easy to pipe into your publisher(s).
npm install node-event-store
Currently, only redis.
npm install node-event-store-redis
var eventStore = require('node-event-store')
var redisStrategy = require('node-event-store-redis')
var RedisClient = require('redis-stream')
var eventStream = require('event-stream')
function aTypicalCommandHandler () {
var store = initializeEventStore()
//by default this will pull
//all events using
//minRevision = 0 && maxRevision=Number.MAX_VALUE
//streamId is typically your Aggregate Root id
var filter = {
streamId: '123'
}
var stream = store.open(filter);
//this bit is handled by _you_ according
//to your domain reqs
var aggregate = createAggregate()
var commandHandler = eventStream.map(phonyAggregateOperation)
var publisher = eventStream.through(publishTheCommit)
stream.pipe(aggregate).pipe(commandHandler).pipe(stream.commit()).pipe(publisher)
}
function initializeEventStore () {
//using database 11 of local redis
//for now, the branch of redis-stream
//at github.com/mnichols/redis-stream/tarball/reply
//but will fold into event-store
//see https://github.com/mnichols/node-event-store/issues/8
var redisCli = new RedisClient(6379, 'localhost', 11)
var redisStorageCfg = {
client: redisCli
}
var redis = redisStrategy.createStorage(redisStorageCfg)
var auditor = redisStrategy.createAuditor(redisStorageCfg)
//include the auditor to get support for
//streaming all events in the store.
//Handy for rebuilding view models or audits
var store = eventStore(redis, auditor)
}
function createAggregate() {
//it's up to you to provide a writable stream
//that receives the events
//node-event-store will hand you.
//For this example, we are just buffering them all
//and then passing them into a another filter.
//From there, we are simply passing on the aggregate root
//but obviously you need to apply the events to your aggregate first :)
var AggregateRoot = function () { }
var ar = new AggregateRoot()
var poolEvents = require('./bucket-stream')
var mapEventsToAgg = eventStream.map(function (events, next) {
ar.events = events
next(null, ar);
})
eventStream.pipeline(poolEvents, mapEventsToAgg)
}
function phonyAggregateOperation (agg, next) {
//do some stuff with aggregate
//and expose events
next(null, {some:'event'})
}
function publishTheCommit (commit) {
//commit.payload is the Array of events
//do stuff here
}Please see the test folder for examples. Especially event-store.spec.coffee.
make test
Or for integration testing
make TEST_TYPE=integration test
See issues
Copyright (c) 2012 Mike Nichols
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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