Deprecation notice

Samples are moved to the core repository.

Bookings sample application - Postgres

This projects shows some of the features of Eventuous:

• Event-sourced domain model using Aggregate and AggregateState
• Aggregate persistence using PostgreSQL
• Read models in MongoDB
• Integration between services using messaging (RabbitMQ)

Usage

Start the infrastructure using Docker Compose from the repository root:

docker compose up

Run both Bookings and Bookings.Payments projects and then open http://localhost:5051/swagger/index.html and http://localhost:5000/swagger/index.html respectively. Here you can use SwaggerUI to initiate commands that will result in events being raised.

Example commands

Bookings -> BookRoom (/bookings/book)

• This command raises an event, which gets stored in the database.
• A real-time subscription triggers a projection, which adds or updates two documents in MongoDB:
  • one for the booking
  • one for the guest

Bookings.Payments -> RecordPayment (/recordPayment)

• When this command is executed, it raises a PaymentRecorded event, which gets persisted to the database.
• A gateway inside the Payments service subscribes to this event and publishes an integration event to RabbitMQ.
• An integration RabbitMQ subscription receives the integration event and calls the Bookings service to execute the RecordPayment command, so it acts as a Reactor.
• When that command gets executed, it raises a PaymentRecorded event, which gets persisted to the database. It might also raise a BookingFullyPaid or BookingOverpaid events, depending on the amount.
• Those new events are projected to MongoDB document in the Bookings collection using the read-model subscription.

Loading

graph TB
    HTTP --> RecordPayment
    subgraph Payments 
    direction LR
    RecordPayment -- aggregate --> PaymentRecorded[PaymentRecorded<br>domain event]
    Reactor --> PR[PaymentRecorded<br>integration event]
    end
    subgraph Postgres
    PaymentRecorded -- eventstore --> PGSQL[(PGSQL)]
    PGSQL -- gateway --> Reactor
    end
    subgraph Broker
    PR --> RabbitMQ[[RabbitmQ]]
    end
    subgraph Bookings
    direction RL
    RabbitMQ -- subscription --> IH[Integration<br>handler]
    IH --> RP[RecordPayment]
    RP -- aggregate --> PR1[PaymentRecorded]
    PR1 -- eventstore --> PGSQL
    PGSQL -- subscription --> Projections
    end
    subgraph MongoDB
    Projections --> BC[(BookingState)]
    Projections --> MB[(MyBookings)]
    end