Hubs

A hub is one named stage of a flow: a list of rules, run in order, plus how the stage behaves.

A stage on its own

The checkout's fraud screen, run by itself:

<?php

use Keaton\PipeDream\PipeHub;

$order = new Order(
    id: 'ord_48213',
    items: [
        ['sku' => 'tee-blk-m', 'name' => 'Black tee', 'price' => 30.00],
        ['sku' => 'hoodie-gry-l', 'name' => 'Grey hoodie', 'price' => 65.00],
        ['sku' => 'cap-nvy', 'name' => 'Navy cap', 'price' => 25.00],
    ],
    shippingAddress: 'Keizersgracht 123, Amsterdam',
    shippingCountry: 'NL',
    billingCountry: 'US',
    discountCode: 'SPRING20',
    cardsTriedRecently: 4,
);

$envelope = PipeHub::create()
    ->name('Fraud screen')
    ->description('Does this look like the real cardholder?')
    ->addPipes([
        MatchBillingToShippingCountry::class,
        CheckCardVelocity::class,
        ScoreDeviceFingerprint::class,
    ])
    ->skipIf(fn ($order) => $order->customerIsTrusted(), 'Trusted customer')
    ->then(fn ($order) => $order->riskSignals() >= 2 ? $order->holdForReview('Two or more fraud signals') : null)
    ->sendIt($order);

echo $envelope->receipt();

Fraud screen · On hold: Two or more fraud signals (0.07 ms)

Fraud screen — Does this look like the real cardholder?
  ✗ MatchBillingToShippingCountry (0.03 ms)  Billing US, shipping NL
  ✗ CheckCardVelocity             (0.01 ms)  4 cards tried on this account in 10 minutes
  ✓ ScoreDeviceFingerprint        (0.01 ms)

A hub run on its own is the whole flow, so its name is the flow's name.

Reading a hub

Each line of a hub answers one question, so read it top to bottom:

• name() and description(): what this stage is, and the question it answers. Both show up on the receipt. Write the description as a question ("Does this look like the real cardholder?"), and the receipt reads like an interview.
• addPipes([...]): the rules, in the order they run.
• skipIf(...): when this stage doesn't apply.
• then(...): what to do once the stage is done. Here: two or more concerns put the order on hold.

Skipping a stage

skipIf() takes a closure. What it returns decides:

So a stage with one reason to skip passes it as the second argument, and a stage with several returns whichever applies. Every rule in a skipped hub is still on the receipt, marked ↷, and the reason is printed once on the hub's line. More on Pass, flag, skip, stop.

Everything a hub does

Next: Flows.