Concepts And Package Map

@haskou/ddd-kernel is split into three layers:

• Core: lifecycle, dependency injection, kernel logging contracts and the Kernel runtime.
• Contracts and domain primitives: stable interfaces and base classes that application code depends on.
• Adapters: optional infrastructure implementations for a contract or runtime boundary.

Application code should usually depend on contracts and domain primitives. Bootstrap code chooses adapters.

Core

Area	Import	Purpose
Kernel runtime	@haskou/ddd-kernel	Registers consumers, routes, schedulers, runtimes and shutdown hooks.
Environment variables	@haskou/ddd-kernel	Loads .env.<environment> files and exposes typed kernel.environment when a schema is configured.
Dependency injection	@haskou/ddd-kernel/dependency-injection	Wraps node-dependency-injection and container YAML generation/loading.
Lifecycle	@haskou/ddd-kernel/lifecycle	Runtime and initializer contracts.
Kernel contracts	@haskou/ddd-kernel/contracts/kernel	KernelConsumer, KernelRoute, KernelLogger, middleware and shutdown contracts.

dotenv, node-dependency-injection and fs-extra are package dependencies because the core environment and DI implementations use them directly. Applications do not install them separately.

Contracts And Domain

Area	Import	Purpose
Domain	@haskou/ddd-kernel/domain	AggregateRoot, DomainEvent, domain event bus contracts and consumer/publisher contracts.
Pub/sub contracts	@haskou/ddd-kernel/contracts/pubsub	Generic message bus, consumer registration and handler contracts.
DB contracts	@haskou/ddd-kernel/contracts/db	Repository-oriented persistence contracts.
UI contracts	@haskou/ddd-kernel/contracts/ui	Route contracts and HTTP status constants.

Adapters

Group	Adapter	Import	Extra packages
Pub/sub	In-memory	@haskou/ddd-kernel/adapters/pubsub/in-memory	None
Pub/sub	AMQP	@haskou/ddd-kernel/adapters/pubsub/amqp	amqplib
DB	In-memory repository	@haskou/ddd-kernel/adapters/db/in-memory	None
DB	Mongo repository	@haskou/ddd-kernel/adapters/db/mongo	mongodb
UI	Express server and HTTP error handling	@haskou/ddd-kernel/adapters/ui/express	express, routing-controllers, reflect-metadata, class-transformer, class-validator; cors only when routingControllersOptions.cors is enabled
UI	Route base class	@haskou/ddd-kernel/adapters/ui/routes	Same runtime as the HTTP server that executes routes
Kernel	Console logger	@haskou/ddd-kernel/adapters/kernel/console	None
Logs	Winston logger	@haskou/ddd-kernel/logs	winston
Scheduler	Cron scheduler base	@haskou/ddd-kernel/scheduler	node-cron
WebSocket	Event hub and realtime server	@haskou/ddd-kernel/websocket	ws

Adapters are optional. Importing the kernel or domain contracts does not require Express, AMQP, MongoDB, Winston or WebSocket packages.

Application Boundary

Use constructor injection inside consumers, schedulers, routes and services. Use bootstrap code to choose infrastructure:

await kernel.dependencyInjection({
  overrides: [
    {
      token: UserRepository,
      useClass:
        process.env.NODE_ENV === 'test'
          ? InMemoryUserRepository
          : MongoUserRepository,
    },
  ],
});

That keeps domain/application code stable while adapters change per runtime.