# Complex Business Processes

## The Problem You Recognize

Your order fulfillment process spans 6 steps across 4 services. The subscription lifecycle involves payment processing, provisioning, notifications, and grace periods. User onboarding triggers a welcome email, account setup, and a follow-up sequence.

The logic for these processes is spread across:

* **Event listeners** that trigger other event listeners
* **Cron jobs** that check status flags
* **Database columns** like `is_processed`, `retry_count`, `step_completed_at`

Nobody can explain the full flow without reading all the code. Adding a step means editing multiple files. Reordering steps is risky. When something fails mid-process, recovery means manually updating database flags.

## What the Industry Calls It

Two distinct patterns solve this, and they're often confused:

* **Workflows** — stateless pipe-and-filter chaining. The message flows from one handler to the next via output channels. Each step is independent; nothing is remembered across steps.
* **Sagas** — stateful long-running coordination. The saga remembers where it is across events that may arrive seconds, minutes, or days apart, and decides what to do next based on prior state.

Neither Symfony Messenger nor Laravel Queues has a first-class equivalent — both stop at "dispatch a job." Ecotone provides both patterns natively.

## How Ecotone Solves It

**Workflows — chained handlers.** Connect handlers through input and output channels. Each handler does one thing and passes the message on. No coordinator, no state; just declarative flow:

```php
#[CommandHandler(
    routingKey: "order.place",
    outputChannelName: "order.verify_payment"
)]
public function placeOrder(PlaceOrder $command): OrderData
{
    // Step 1: Create the order, pass to next step
}

#[Asynchronous('async')]
#[InternalHandler(
    inputChannelName: "order.verify_payment",
    outputChannelName: "order.ship"
)]
public function verifyPayment(OrderData $order): OrderData
{
    // Step 2: Verify payment, pass to shipping
}
```

**Sagas — stateful coordination.** Track state across events that arrive over time. The saga remembers where it is and reacts to each event based on what came before:

```php
#[Saga]
class OrderFulfillment
{
    #[Identifier]
    private string $orderId;
    private string $status;

    #[EventHandler]
    public static function start(OrderWasPlaced $event): self
    {
        // Begin the saga — tracks state across events
    }

    #[EventHandler]
    public function onPaymentReceived(PaymentReceived $event, CommandBus $bus): void
    {
        $this->status = 'paid';
        $bus->send(new ShipOrder($this->orderId));
    }
}
```

## Next Steps

* [Handler Chaining](/modelling/business-workflows/connecting-handlers-with-channels.md) — Simple linear workflows
* [Sagas](/modelling/business-workflows/sagas.md) — Stateful workflows that remember
* [Handling Failures](/modelling/business-workflows/handling-failures.md) — Recovery and compensation

{% hint style="success" %}
**As You Scale:** Ecotone Enterprise adds [Orchestrators](/modelling/business-workflows/orchestrators.md) — declarative workflow automation where you define step sequences in one place, with each step independently testable and reusable. Dynamic step lists adapt to input data without touching step code.
{% endhint %}


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