daviddykeuk / cqrs-example-service

CQRS Example

This project is an example of how to apply a CQRS pattern for a microservice project. It utilises event sourcing as a single source of immutable truth for its ecosystem, processing commands and transactions to the hub, subscribing to the event stream, aggregating them and then allow them to be queried.

At first glance this project may look like overkill for a pretty simple CRUD service, but out of the box you get a lot of extensible functionality.

• A single source of truth
• Prevention of race conditions
• Audit logging
• The ability to add new views to manipulate the data in any peceived way without effecting the underlying system, using any type of technology

Running

The system uses mongodb and a docker image for the event-hub daviddyke/cqrs-event-hub, as well as a generic api gateway for accessing turbosonic/api-gateway the rest of the code can be run from the docker-compose file.

$ docker-compose up

NONE OF THIS PROJECT IS PRODUCTION READY CODE (yet)

cqrs-example-service's Issues

performTransaction can accept a non-integer amount

It's possible to submit transaction.amount as a string, which will break the balance returned.

Example:

PUT /accounts/id

{
	"description": "deposit a milli",
	"amount": "1000000"
}
...
{
	"description": "buy a flat",
	"amount": -380000
}

Would result in:

GET /accounts/id

{
	...,
	"balance": "1000000-380000",
	...
}