README

Layer 1 — transactional outbox domain model and publish lifecycle

This package defines contracts and invariants for the transactional outbox pattern: enqueue integration messages in the same unit of work as business state, then publish asynchronously with explicit pending → sending → sent | failed semantics.

It is not a message broker, queue driver, or database layer. Persistence and workers live in Layer 3 adapters. InMemoryOutboxStore is for tests and single-process use only (not a cross-process concurrency model; L3 should use row locking and unique constraints).

When to use

You need reliable fan-out to Notifier, webhooks, analytics, or external systems after a successful commit.
You pair with Nexus\EventStream when the system of record is an append-only stream but integrators do not consume the stream directly — see docs/event-stream-bridge.md.

When not to use

Event sourcing / replay of aggregate history → Nexus\EventStream.
HTTP command idempotency (replay-safe API results) → Nexus\Idempotency.
Exactly-once end-to-end delivery — not guaranteed; consumers must be idempotent or deduplicate (this package provides exactly-once intent at enqueue for a given dedup key within tenant scope).

Core types

Type	Role
`OutboxServiceInterface`	Enqueue, claim next pending, mark sent/failed, schedule retry
`OutboxStoreInterface`	Composite query + persist (split interfaces available)
`OutboxClockInterface`	UTC `now()` for transitions and lease checks
`InMemoryOutboxStore`	Tests and local simulations

Example (sketch)

use Nexus\Outbox\Domain\OutboxEnqueueCommand;
use Nexus\Outbox\Services\InMemoryOutboxStore;
use Nexus\Outbox\Services\OutboxService;
use Nexus\Outbox\Services\SystemClock;
use Nexus\Outbox\ValueObjects\DedupKey;
use Nexus\Outbox\ValueObjects\EventTypeRef;
use Nexus\Outbox\ValueObjects\TenantId;

$tenantId = new TenantId('tenant-1');
$store = new InMemoryOutboxStore();
$clock = new SystemClock();
$outbox = new OutboxService($store, $store, $clock);

$now = $clock->now();
$leaseExpiresAt = $now->modify('+5 minutes');

$result = $outbox->enqueue(new OutboxEnqueueCommand(
    $tenantId,
    new DedupKey($streamEventId),
    new EventTypeRef($eventTypeFqcn),
    $payload,
    $metadata,
    $correlationId,
    $causationId,
    $now,
));

$claimed = $outbox->claimNextPending($tenantId, $leaseExpiresAt);
if ($claimed !== null) {
    // publish to external bus, then:
    $outbox->markSent($tenantId, $claimed->id, $claimed->claimToken);
}

Requirements

PHP 8.3+

azaharizaman / nexus-outbox

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