Event-Driven Workflow

Wait for external webhook events.

payment_flowPending

payment_flow.ex

defmodule MyApp.PaymentFlow do
  use Durable
  use Durable.Helpers
  use Durable.Wait

  workflow "payment_flow" do
    step :create_invoice, fn ctx ->
      invoice = Invoices.create(ctx["order_id"], ctx["amount"])
      {:ok, %{order_id: ctx["order_id"], invoice_id: invoice.id}}
    end

    step :await_payment, fn ctx ->
      {event, _payload} = wait_for_any(["payment.success", "payment.failed"],
        timeout: days(7),
        timeout_value: {"payment.expired", nil}
      )
      {:ok, assign(ctx, :result, event)}
    end

    branch on: fn ctx -> ctx.result end do
      "payment.success" ->
        step :fulfill, fn ctx ->
          Orders.fulfill(ctx.order_id)
          {:ok, assign(ctx, :status, :fulfilled)}
        end

      _ ->
        step :cancel, fn ctx ->
          Orders.cancel(ctx.order_id)
          {:ok, assign(ctx, :status, :cancelled)}
        end
    end
  end
end

# Webhook handler sends event
Durable.send_event(workflow_id, "payment.success", %{transaction_id: "txn_123"})

The code is the README example. The run is simulated in your browser, with time sped up. For the details, read the waiting guide.