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2017 © Pedro Peláez
A lightweight command bus implementation
Minibus helps separate your interface from your implementation - like your REST handlers from your database calls., (*1)
It was inspired by Grafana's command bus and the Tactician command bus library., (*2)
What a command bus allows is the decoupling of what needs done from how it gets done. As systems get more complex, keeping the interface separate from the implementation like this improves maintainability., (*3)
Ross Tuck gave an exemplary talk outlining service layers and command busses - I recommend you watch this if you think you need a command bus., (*4)
Via composer: composer require austinhyde/minibus, (*5)
Minibus provides an extremely simple command bus implementation out of the box: Minibus\Bus., (*6)
This gives you everything you need to begin dispatching commands and publishing events:, (*7)
$bus = new Minibus\Bus;
$bus->addHandler(function(NewUserCommand $cmd) use ($db, $bus) {
$row = $db->query("INSERT INTO users (username, email) VALUES (?, ?) RETURNING *",
[$cmd->username, $cmd->email]);
$user = User::fromRow($row);
$bus->publish(new UserAddedEvent($user));
return $user;
});
$bus->addListener(function(UserAddedEvent $event) use ($log) {
$log->info("Added user: " . $event->getUser()->getUsername());
});
$router->get(function($req, $res) use ($bus) {
$cmd = new NewUserCommand($req->body->username, $req->body->email);
$user = $bus->dispatch($cmd);
return $user->toJson();
});
addHandler and addListener take any callable as their first argument, and automatically infer the type of
command or event they'll be registered for by reflecting the type hint of the first parameter. If you want to
override the "type" of the command or event (not necessarily a class name), you can specify a type as the second
parameter., (*8)
dispatch and publish will accept any value as a command or event, although if they're an object, Minibus
will use the class name to automatically find the correct command handler or event listeners. Again, you can override
the "type" by passing it as the second parameter., (*9)
A lightweight command bus implementation
MIT
MIT
MIT