ASP.NET Core REST API for DDD Event Sourced to EventStore

Setup

Optionally configure a GES EventStore:

• By setting either the EventStoreOptions:ServerUri environment variable or command line argument:

dotnet run /EventStoreOptions:ServerUri=tcp://admin:changeit@localhost:1113

• By creating a appsettings.json file in the output directory (ie. src\WebApp\bin\Debug\netcoreapp1.0):

{
	"EventStoreOptions": {
		"ServerUri": "tcp://admin:changeit@localhost:1113"
	}
}

Event type projections ($et- streams) are used so projections must be enabled.

If no ServerUri is provided a fake in-memory EventStore is used. This can be tried by omitting the appsettings.json file altogether or simply commenting the ServerUri line by prepending // to it.

Run:

cd src\WebApp
dotnet restore
dotnet run

Endpoints

A Swagger interface definition is available at /swagger/v1/swagger.json with a web interface at /swagger/ui. Both are automatically generated by Swashbuckle.

Examples (note that you can also easily try them out through the Swagger web interface):

1. Create

curl -X POST -H "Content-Type: application/json" -H "Cache-Control: no-cache" -d '{
    Name: "test"
}' "http://localhost:5000/api/Team/63931ea8-3f83-487c-8f21-01577a5157f9"

2. Update

curl -X PUT -H "Content-Type: application/json" -H "Cache-Control: no-cache" -d '{
    NewName: "updated!!",
    OriginalVersion: 0
}' "http://localhost:5000/api/Team/63931ea8-3f83-487c-8f21-01577a5157f9/name"

3. Retrieve all

curl -X GET -H "Cache-Control: no-cache" "http://localhost:5000/api/Team"

4. Retrieve one

curl -X GET -H "Cache-Control: no-cache" "http://localhost:5000/api/Team/63931ea8-3f83-487c-8f21-01577a5157f9"

5. Retrieve a previous version

curl -X GET -H "Cache-Control: no-cache" "http://localhost:5000/api/Team/63931ea8-3f83-487c-8f21-01577a5157f9/0"

6. Delete

curl -X DELETE -H "Content-Type: application/json" -H "Cache-Control: no-cache" -d '{
    OriginalVersion: 1
}' "http://localhost:5000/api/Team/63931ea8-3f83-487c-8f21-01577a5157f9"  

Projects

• Reads
  • ReadModel.Teams: read model serving the queries. Loads a fake snapshot on start (state restored from the event store) and then reacts to domain events to update its own model. Queries are replied using this model.
• Writes
  • BoundedContext.Teams: domain and command processing.
  • EventStoreFacade: event storage to GES:
• Infrastructure.Domain: DDD, CQRS, and Event Sourcing infrastructure. Originated from Greg Young's simple CQRS example.
• WebApp: web API.

Main components

• Messaging
  • IMessage
  • ICommand: command request message
  • Event: published event message
  • IHandle: message type handler
• Bus
  • IMessageBroker: manage message handlers
  • IEventPublisher: event publishing
  • ICommandSender: command requests
• Storage
  • IRepository<AggregateRoot, Event>: enumerate, find and save aggregates
  • IEventStore: load and save events

Bootstrapping

Takes place in WebApp.Startup:

• At ConfigureServices dependency injection is configured with instances of ICommandSender, IEventPublisher, IMessageBroker, and IEventStore, as well the different aggregate roots repositories.
• At Configure the read and write models are configured by registering the proper command and event handlers, and populating the read views with the initital data.

Docker support

The docker folder contains a Dockerfile, a docker-compose.yml and several .bat scripts.

Optionally launch an EventStore container:

docker pull eventstore/eventstore
docker run -d -p 2113:2113 -p 1113:1113 eventstore/eventstore

Compile the application, build the image and run the container:

cd docker
dotnet restore ..\src\WebApp\WebApp.csproj && dotnet publish ..\src\WebApp\WebApp.csproj -o ..\..\docker\publish
docker build -t webapp . --no-cache
docker run -it -p 5000:80 webapp /EventStoreOptions:ServerUri=tcp://admin:changeit@172.17.0.1:1113

(Remove the EventStoreOptions:ServerUri argument to opt out.)

Alternatively, both containers can be launched simply through:

docker-compose up