Ratpack Event Store POC

Work in Progress

Writing an event store proof of concept.

Goals

Event Sourcing model:

• Event
• Snapshot
• Aggregate

TODOs

• Write events from JSON to Cassandra
• Load Events from Cassandra
• Build Aggregate from events loaded from Cassandra

Nice to have TODOs

• Apache Avro for model storage and aggregate compatibility checks?

Demo Model

Events:

• Ride / Riding / Stop
• Lock / Unlock
• Turn on light(s)
• Turn off light(s)
• Inflate tire
• Pressure Check

Aggregate: Bicycle

• Location
• Speed
• Direction
• Front Light status / battery
• Rear Light status / battery
• Lock status
• Tire Pressure

Getting Setup

There be dragons

⚠️ I assume you have aliased your docker host as docker. I do this by putting the IP for docker in your /etc/hosts

• On linux, this is most likely localhost
• On a Mac (and Windows???) via boot2docker this is most likely soemthing like 192.168.59.103 boot2docker config will give you your IP if you don't know it. (see LowerIP in the output)

Running Cassandra in a docker container

docker pull cassandra:2.2
docker run --name evsrc-cassandra -p 9042:9042 -d cassandra:2.2

Running Elasticsearch in a docker container

docker pull elasticsearch:1.7
docker run --name evsrc-elasticsearch -p 9200:9200 -p 9300:9300 -p 54328:54328 -d elasticsearch:1.7

Demo

See the test.sh script for some demo command that push or pull data from the service, or search elastic search for downstream aggregates.