Command Bus Component

This standalone component implements the Command Pattern.

It is inspired by the Laravel illuminate/bus and illuminate/queue components, but aims to be framework agnostic.

For more information about the Command Bus Pattern:

• http://en.wikipedia.org/wiki/Command_pattern
• http://sourcemaking.com/design_patterns/command

Usage

Any Command requires two classes: the DoSomethingCommand class and the DoSomethingHandler class.

You can instantiate the Command from your controllers when needed, and dispatch it onto the Bus.

The Bus will then resolve the matching Handler class, and ask it to handle the new Command.

Here's how you use it:

An example Command class:

<?php

use LinkORB\Component\Bus\CommandInterface;

class OrderConfirmCommand implements CommandInterface
{
    private $orderId;
    public function __construct($orderId)
    {
        $this->orderId = $orderId;
    }
    
    public function getOrderId()
    {
        return $this->orderId;
    }
}

An example Handler class:

<?php

use LinkORB\Component\Bus\HandlerInterface;
use LinkORB\Component\Bus\CommandInterface;

class OrderConfirmHandler implements HandlerInterface
{
    private $db;
    private $mailer;
    
    // the constructor automatically receives requested services from the container
    public function __construct($db, $mailer)
    {
        $this->db = $db;
        $this->mailer = $mailer;
    }

    // this method is called by the bus to handle commands
    public function handle(CommandInterface $command)
    {
        $order = $this->db->fetchOneById('orders', $command->getOrderId());
        $this->mailer->mail($order['email'], "Thanks for your order, " . $order['customername']);
        
    }
}

Setting up the bus in your init script

use LinkORB\Component\Bus\Bus;

// Reuse an existing container, or create a plain php array
// Any array type dependency injection container will work too (symfony, pimple, etc)
$container = array(
    'db'=>$db,
    'mailer'=>$mailer
);

// Instantiate the bus, and optionally pass a container
$bus = new Bus($container);

// now add the bus to the container, or use any other method to pass the bus to your controllers

Using the bus in your Controllers:

class basketController
{
    public function confirmAction()
    {
        $orderid = 5;

        // Instantiate a Command
        $command = new OrderConfirmCommand($orderid);

        // Dispatch the command
        $this->bus->dispatch($command);
    }
}

Calling commands from the command-line

A simple command-line dispatcher is included. It can be used like this:

./vendor/bin/bus bus:dispatch "Acme\Bus\DoSomethingCommand" -p color="red" -g os="linux"

The -p arguments will be passed as parameters to the command. You can pass as many as you want. The -g arguments will be inserted into a simple array "container", so it can be used by the Handlers

One example command is included:

./vendor/bin/bus bus:dispatch "LinkORB\Component\Bus\Bus\HelloCommand" -p name="World" -g sender="me"

This will output:

Hello, World from me!

License

MIT (see LICENSE.md)

Brought to you by the LinkORB Engineering team

Check out our other projects at linkorb.com/engineering.

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