Event Machine is a rapid application development (RAD) framework so let us jump directly into the practical part of the tutorial. Event Machine basic concepts will be explained throughout the tutorial. Once finished, you should be able to start with your own project. The API docs will help you along the way.
Our team can help you to take the first steps and work out a solid foundation for your project based on the power and speed offered by Event Machine. If you're interested in workshops or commercial support, get in touch.
We will build a backend for a small application where you can register buildings and then check in and check out
users in the buildings. The backend will expose a messagebox endpoint that excepts commands and queries.
Each time a user is checked in or checked out we get a notification via a websocket connection.
Credits: The tutorial domain is the same as the one used by Marco Pivetta in his CQRS and Event Sourcing Workshops.
Please make sure you have Docker and Docker Compose installed.
Note: Docker is THE ONLY supported set up at the moment. If you don't want to install docker you need PHP 7.1+ and Postgres 9.4+.
Change into your working directory and use composer to create a new project based on the event machine skeleton
using prooph-em-buildings as project name.
$ docker run --rm -it -v $(pwd):/app prooph/composer:7.1 create-project proophsoftware/event-machine-skeleton prooph-em-buildings
Change into the newly created project dir prooph-em-buildings, start the docker containers and run the set up script
for the event store.
$ cd prooph-em-buildings
$ sudo chown -R $(id -u -n):$(id -g -n) .
$ docker-compose up -d
$ docker-compose run php php scripts/create_event_stream.php
The last command should output done. otherwise it will throw an exception.
Verify database set up by connecting to the Postgres database using:
host: localhost
port: 5432
dbname: event_machine
user: postgres
pwd:
Note: Credentials are defined in app.env and can be changed there.
You should see three tables: event_streams, projections and _<sha1>. The latter is a table created by prooph/event-store.
It will contain all domain events.
Head over to http://localhost:8080 to check if the containers are up and running.
You should see a "It works" message.
By default Event Machine exposes commands (we will learn more about them in a minute), events and queries via a message box endpoint. We can use Swagger UI to interact with the backend.
The Event Machine skeleton ships with a ready to use Swagger UI. Open http://localhost:8080/swagger/index.html
in your browser and try the built-in HealthCheck query.
You should get a JSON response similar to that one:
{
"system": true
}
If everything works correctly we are ready to implement our first use case: Add a building
Note: If something is not working as expected (now or later in the tutorial) please check the trouble shooting section of the event-machine-skeleton README first.