Contracts

Common interfaces for PHP Complex Heart SDK.

Domain Layer

Model

Core building blocks for domain-driven design:

• Aggregate - Root entity with domain event publishing
• Entity - Domain object with unique identity
• ValueObject - Immutable domain value with equality
• Identifier - Unique identifier representation

Events

Domain event interfaces following ISP (Interface Segregation Principle):

• Event - Base domain event (eventId, eventName, payload, occurredOn)
• Traceable - Distributed tracing (correlationId, causationId)
• Sourceable - Event sourcing (aggregateId, aggregateType, eventVersion)
• EventBus - Publishes domain events

Application Layer

Command

Write operations (CQRS):

• Command - Marker interface for state-changing operations
• CommandBus - Dispatches commands to handlers
• CommandHandler - Executes commands

Query

Read operations (CQRS):

• Query - Marker interface for data retrieval
• QueryResponse - Marker interface for query results
• QueryBus - Routes queries to handlers
• QueryHandler - Executes queries and returns responses

Handler

Event handlers:

• EventHandler - Reacts to domain events

Service Bus

Unified message bus facade:

• ServiceBus - Provides access to CommandBus, QueryBus, and EventBus

Architecture

This library follows Clean Architecture principles with explicit layer separation:

• Domain → Application - Domain layer is independent, Application depends on Domain
• Layer-Explicit Namespaces - Clear architectural boundaries in namespace structure
• Interface Segregation - Compose only needed capabilities (e.g., Event + Traceable + Sourceable)

Architecture Testing

The project includes automated architecture tests using Pest PHP:

composer test

Tests enforce:

• Domain layer independence (no Application dependencies)
• Correct interface placement and usage
• Clean Architecture dependency rules
• PHP and security best practices (via arch presets)