README

A simple command bus that uses the middleware pattern for processing commands.

It has been designed to leaverage Dependency Injection with Autowiring support. All of it's dependencies and be configured & overridden by a dependency injection container

Main Features

• All Dependancies are injected at construction
• All Dependencies are based on interfaces
• Route Commands differently based on custom middleware
• Use simple arrays for middleware configuration
• Uses Dependency Injection Container when loading middleware
• Uses Dependency Injection Container when loading handlers

Limitations

• Does not inject dependencies for methods other than __constructor
• Does not inject dependencies for setters

Requirements

• PHP 7
• Container-Interop - Dependancy Injection Container
• GunnaPHP\Invoker

Optional

• KodCube\DependencyInjection - Dependancy Injection Container
• KodCube\MessageBus - Dispatching commands to background processes

Usage

• Create Command Bus
• Dispatch Command
• Override Command Handler
• Multiple Handlers

Create Command Bus

This will create a command bus with the default handler detection

$commandbus = new KodCube\CommandBus\CommandBus(
			        new KodCube\CommandBus\MiddlewareManager(
			        	new KodCube\DependencyInjection\Container()
			        )
              );

or using dependancy injection container

DI Config
[
	MiddlewareManagerInterface::class => MiddlewareManager::class,
	ContainerInterface::class => Container::class
]

$commandbus = $di->get(KodCube\CommandBus\CommandBus::class);

Dispatch Command

Assuming you have the following command and handler

Command Class: MyCommand

Handler Class: MyHandler

$command = new MyCommand();

$response = $commandbus($command);
or 
$response = $commandbus->handle($command);

is the equivalant to

$command = new MyCommand();
$handler = new MyHandler();

$response = $handler($command);

Override Command Handler

The default handler middleware allows you to override which handler is responsible for handling the command

$commandbus = new KodCube\CommandBus\CommandBus(
			        new KodCube\CommandBus\MiddlewareManager(
			        	new KodCube\DependencyInjection\Container(),
			        	new KodCube\CommandBus\Middleware\Handler(
			        		[
			        			MyCommand::class => MyNewHandler::class
			        		]
			        	)
			        )
              );

is the equivalant to

$command = new MyCommand();
$handler = new MyNewHandler();

$response = $handler($command);

or using dependancy injection container

DI Config
[
	MiddlewareManagerInterface::class => MiddlewareManager::class,
	ContainerInterface::class => Container::class
	Handler::class => [
		[
			MyCommand::class => MyNewHandler::class
		]
	]
]

$commandbus = $di->get(KodCube\CommandBus\CommandBus::class);

Multiple Middlerware Handlers

Using the middleware capablies we can easily add multiple command handlers, to process some commands differently from others.

In this example we add a Queueable Middleware Handler, that will look for commands that implement a CommandQueueInterface::class.

Theses commands will be routed to a message bus for processing on a background process, were as all other command will be handled by the final middleware handler.

$commandbus = new KodCube\CommandBus\CommandBus(
                new KodCube\CommandBus\MiddlewareManager(
                    [
                      KodCube\CommandBus\Middleware\Queue::class,
                      KodCube\CommandBus\Middleware\Handler::class
                    ],
                    new KodCube\DependencyInjection\Container(), 
			      )
              );

or using dependancy injection container

DI Config
[
	MiddlewareManagerInterface::class => MiddlewareManager::class,
	MiddlewareManager::class => [
		Middleware\Queue::class,
		Middleware\Handler::class
	],
	ContainerInterface::class => Container::class,
	Handler::class => [
		[
			MyCommand::class => MyNewHandler::class
		]
	]
]

$commandbus = $di->get(KodCube\CommandBus\CommandBus::class);