Ktor Ports and Adapters Multi Module Template

A dummy services that illustrates:

• Ports and Adapters
• Multi-module gradle kotlin dsl
• Guice injection with Ktor

Testing

Run ./gradlew clean test to run all the tests

Running locally

Create the directory /app/lib/conf and add a file called 'jwt-secret.conf'

jwt.secret = 1234-1234-1234-1234

Run ./gradlew :app:run to run the service

Project Structure

This project follows a 'ports and adapters' (a.k.a. hexagonal) architecture and is divided into modules

Domain

The centre of the hexagon, contains core business logic.

Depends on

• Ports

What goes here?

• Classes and functions related to business logic.

What does not go here?

• Transport layer concerns, e.g. JSON transformation,
• Frameworks (arguable - but try to avoid)
• Databases (arguable - but lets try to be pure)

Adapters

Everything outside the hexagon. Nothing related to business logic.

Depends on

• Ports

What goes here?

• JSON serializers/deserializers
• REST clients
• RabbitMQ senders/receivers (if applicable)
• Framework code, e.g. ktor routes
• DAOs, data layer

What does not go here?

• Business logic

Ports

The 'ports' layer is the only way 'domain' and 'adapters' interact. It is divided into:

• Provided (by domain)
• Required (by domain

Depends on

• Nothing

Provided ports

Interfaces (and data classes) implemented by the domain sub-project. The adapter layer uses this to communicate with domain code.

What goes here?

• Interfaces for domain services

What does not go here?

• Anything else

Required ports

Interfaces (and data classes) implemented by the adapters sub-project. The domain layer uses this to communicate with adapter layer.

What goes here?

• Interfaces for remote services, message brokers, repositories, etc.

What does not go here?

• Anything else

App

This layer can see all other layers and is responsible for bootstrapping the running application

Depends on

• Ports
• Adapters
• Domain

What goes here?

• The 'main method'
• Framework configuration needed to glue the other layers together, e.g. initializing Guice modules
• Build configuration needed to create a deployable service.

What does not go here?

• Anything that otherwise fits into the 'ports', 'adapters' or 'domain' buckets