Laravel Event Sourcing Laravel Package

Product Decisions This Supports

• Feature Development:

  • Implement audit trails for critical business operations (e.g., financial transactions, user actions) with immutable event logs.
  • Build temporal queries (e.g., "Show me all state changes for this order in the last 30 days") without complex database joins.
  • Enable real-time projections (e.g., dashboards, notifications) by subscribing to events via reactors or projectors.
  • Support CQRS (Command Query Responsibility Segregation) by decoupling read and write models, improving scalability for high-traffic APIs.

• Roadmap Alignment:

  • Phase 1: Pilot event sourcing for a high-value but low-risk feature (e.g., user account history) to validate architectural benefits.
  • Phase 2: Expand to core domains (e.g., orders, payments) where temporal consistency and replayability are critical.
  • Phase 3: Integrate with event-driven microservices or serverless functions to extend event sourcing beyond Laravel.

• Build vs. Buy:

  • Buy: Avoid reinventing event sourcing infrastructure (e.g., event storage, projection management). This package abstracts complexity while providing Laravel-native tooling.
  • Custom Build: Only consider if requirements exceed the package’s scope (e.g., multi-region event replication, custom event serialization).
  • Hybrid: Use the package for core event sourcing but extend with custom logic for niche use cases (e.g., blockchain-based event validation).

• Use Cases:

  • Compliance/Auditing: Regulated industries (finance, healthcare) needing unalterable logs for SOX, GDPR, or HIPAA.
  • Complex Workflows: Multi-step processes (e.g., e-commerce orders, loan approvals) where state transitions must be traceable.
  • Real-Time Systems: Chat apps, live collaborations, or IoT where event-driven updates reduce latency.
  • Data Migration: Safely replay events to backfill projections during schema changes or system upgrades.

When to Consider This Package

Adopt This Package If:

• Your Laravel app requires temporal data integrity (e.g., "I need to prove this state was valid at time T").
• You’re building a domain where history matters (e.g., financial ledgers, medical records, legal documents).
• Your team lacks event sourcing expertise but wants a Laravel-friendly starting point (avoids low-level complexity).
• You need audit trails without manual logging (e.g., tracking every change to a resource via events).
• Your read models (e.g., dashboards, reports) can be rebuilt from events (projections) instead of syncing with a primary database.
• You’re using Laravel Queues or Horizon and want to extend event processing with reactors (e.g., triggering notifications on events).

Look Elsewhere If:

• Your use case is simple CRUD with no need for event logs or temporal queries.
• You require event sourcing at scale (e.g., millions of events/sec)—this package may need optimization or a dedicated solution like EventStoreDB or Kafka.
• Your team lacks PHP/Laravel expertise—event sourcing adds architectural complexity that may slow development.
• You need multi-language support (this is PHP/Laravel-specific; consider Axoni or Eventuous for polyglot persistence).
• Your events require custom serialization (e.g., Protocol Buffers) or off-chain validation (e.g., smart contracts).

How to Pitch It (Stakeholders)

For Executives (Business/Strategy):

*"This package lets us adopt event sourcing—a pattern where every state change in our system is recorded as an immutable event. Think of it like a time machine for our data:

• Audit-ready: Every action is logged, so we can prove compliance with regulations like GDPR or SOX without manual tracking.
• Future-proof: We can rebuild our entire database from events if needed (e.g., after a migration or disaster).
• Real-time insights: By projecting events into dashboards or notifications, we can surface critical updates instantly (e.g., fraud alerts, order status changes).
• Low risk: Spatie’s package handles the heavy lifting in Laravel, so we avoid years of custom infrastructure work.

Why now? If we’re building [Feature X] or scaling [System Y], event sourcing could reduce technical debt and unlock features like temporal queries or decision replay. Let’s pilot it for [Low-Risk Use Case] to validate the ROI."*

For Engineering (Technical):

*"This package provides a batteries-included way to implement event sourcing in Laravel, covering:

• Aggregates: Encapsulate business logic and emit events (e.g., OrderCreated, PaymentFailed).
• Projectors: Rebuild read models (e.g., orders table) from events for queries.
• Reactors: Side-effect handlers (e.g., send email on OrderShipped).
• Event Storage: Persist events in a PostgreSQL/MySQL table with Laravel’s query builder.

Key Benefits:

• No event store vendor lock-in: Uses Laravel’s DB, but can be swapped later.
• Seamless with Laravel: Works with Eloquent, Queues, and existing tooling.
• Performance: Optimized for Laravel’s ecosystem (e.g., event batching, projection caching).

Trade-offs:

• Learning curve: Event sourcing changes how we think about state (e.g., no direct DB writes).
• Projection maintenance: Read models must stay in sync with events.

Proposal: Start with a single aggregate (e.g., UserAccount) to test the pattern. If successful, expand to [High-Impact Domain]."*

For Developers (Implementation):

*"Here’s how you’d use it in code:

// 1. Define an Aggregate (e.g., Order)
class Order extends Aggregate
{
    public function createOrder(OrderCreated $event)
    {
        $this->recordThat($event);
    }

    public function markAsPaid(OrderPaid $event)
    {
        $this->recordThat($event);
    }
}

// 2. Project events into a read model
Event::projector()
    ->for(OrderCreated::class)
    ->create(function (OrderCreated $event) {
        Order::query()->create($event->toArray());
    });

// 3. React to events (e.g., send notifications)
Event::reactor()
    ->for(OrderShipped::class)
    ->perform(fn (OrderShipped $event) => Notification::send(...));

Docs: Spatie’s Guide covers aggregates, projections, and testing.

Next Steps:

1. Set up the package (composer require spatie/laravel-event-sourcing).
2. Design your first aggregate (start simple!).
3. Build a projector for your read model.
4. Test event replay to ensure data integrity."*