Application Service Implementation Standard

Purpose

Application services execute use cases for a module. They coordinate security context, validation, domain behavior, repositories, events, outbox records, and integration ports.

Responsibilities

Responsibility	Standard
Use-case orchestration	Execute one command or query responsibility.
Authorization context	Ensure Identity, Billing entitlement, and domain policy checks are satisfied.
Transaction boundary	Own transaction scope for state-changing use cases.
Domain coordination	Load aggregates and invoke domain behavior.
Persistence	Use module-owned repositories only.
Event publication	Publish past-tense events and write outbox records where required.
Audit	Produce audit context for material actions.

Rules

• Application services do not contain persistence SQL or HTTP details.
• Commands must not return internal aggregates.
• Queries must not mutate state.
• Synchronous cross-module calls require explicit approval and should prefer published application boundaries.
• Event-driven coordination is preferred for cross-module workflow reactions.
• AIOS writes become state only through owning application services.

Use-Case Flow

sequenceDiagram
    participant Controller
    participant App as Application Service
    participant Domain
    participant Repo as Repository
    participant Outbox

    Controller->>App: Command or query
    App->>Repo: Load owned state
    App->>Domain: Apply behavior or policy
    App->>Repo: Persist owned state
    App->>Outbox: Record event if required