Event Extension Architecture

Events provide extension points for loading additional data or reacting to system changes. They are designed for observation and enrichment, not for altering core control flow.

Design Principles

• Events expose extension points without breaking encapsulation.
• Events should not mutate core program flow.
• Business logic replacement must use decoration, not events.
• Events must remain predictable and side-effect aware.

Extension Guidelines

• Use events to add data, not to override behavior.
• Avoid heavy computation or database queries inside event subscribers.
• Keep subscribers idempotent and deterministic.
• Prefer decoration when you need to change logic execution.

Technical Requirements

• Events must always implement the \Shopware\Core\Framework\Event\ShopwareEvent interface.
• Sales channel events must implement these interfaces:
  • ShopwareSalesChannelEvent
  • \Shopware\Core\Framework\Event\SalesChannelAware
• Events are intended for enrichment and extension, not for control-flow modification.