SimpleBus

Installation

Using Composer:

composer require simple-bus/command-bus

Usage

Create a command

use SimpleBus\Command\Command;

class RegisterUserCommand implements Command
{
    const NAME = 'register_user';

    public $email;

    public function name()
    {
        return self::NAME;
    }
}

Create a command handler

use SimpleBus\Command\Command;
use SimpleBus\Command\Handler\CommandHandler;

class RegisterUserCommandHandler implements CommandHandler
{
    public function handle(Command $command)
    {
        // do anything to handle the command
    }
}

Set up the command bus and the command handler resolver:

use SimpleBus\Command\Bus\DelegatesToCommandHandlers;
use SimpleBus\Command\Handler\LazyLoadingCommandHandlerResolver;

$commandHandlerResolver = new LazyLoadingCommandHandlerResolver(
    function ($serviceId) {
        // lazily load/create an instance of the command handler, e.g. using a service locator
         $handler = ...;

         return $handler;
    },
    array(
        RegisterUserCommand::NAME => 'register_user_command_handler_service_id'
    )
);

$commandBus = new DelegatesToCommandHandlers($commandHandlerResolver);

$registerUserCommand = new RegisterUserCommand();
$registerUserCommand->email = 'matthiasnoback@gmail.com';

$commandBus->handle($registerUserCommand);

Because a command handler might call the command bus to handle new commands, it's better to wrap the command bus to make sure that the first command is fully handled first:

use SimpleBus\Command\Bus\FinishesCommandBeforeHandlingNext;

$commandBusWrapper = new FinishesCommandBeforeHandlingNext();
$commandBusWrapper->setNext($commandBus);

$commandBusWrapper->handle($registerUserCommand);

Extension points

Specialized command buses

You can add your own specialized command bus implementations. You can chain them using CommandBus::setNext().

If your command bus needs to call the next command bus in the chain, use the RemembersNext trait to prevent some code duplication:

use SimpleBus\Command\Bus\RemembersNext;

class SpecializedCommandBus implements CommandBus
{
    use RemembersNext;

    public function handle(Command $command)
    {
        ...

        // call the next command bus in the chain
        $this->next($command);
    }
}

Load command handlers in a different way

The DelegatesToCommandHandlers command bus uses a CommandHandlerResolver to find the right handler for a given command object. You can implement your own strategy for that of course, just make sure your class implements the CommandHandlerResolver interface.

jenkoian / CommandBus