Installing the PHP client

The problem

RabbitMQ speaks AMQP, a wire protocol your PHP code has no idea how to talk on its own. It needs a library that knows how to open a connection, send frames, and read the replies. The standard, battle-tested client is php-amqplib/php-amqplib, so the first job in this chapter is to install php-amqplib and open a connection. Everything that follows builds on it.

First, make sure a broker is actually running. If you followed run RabbitMQ with Docker, you already have one listening on localhost:5672.

Install with Composer

From your project folder, pull the library in with Composer:

composer require php-amqplib/php-amqplib

That adds the package to composer.json and generates the autoloader. From now on a single require 'vendor/autoload.php'; gives you access to the client's classes.

Open a connection and a channel

Remember from connections and channels that a connection is one TCP link to the broker, and a channel is a lightweight virtual connection inside it where the real work happens. You almost always open one connection and then one channel on top of it.

<?php

require 'vendor/autoload.php';

use PhpAmqpLib\Connection\AMQPStreamConnection;

$connection = new AMQPStreamConnection('localhost', 5672, 'guest', 'guest');
$channel = $connection->channel();

echo "Connected to RabbitMQ\n";

$channel->close();
$connection->close();

Let's read it line by line:

• require 'vendor/autoload.php'; loads Composer's autoloader so the client classes are found without manual requires.
• AMQPStreamConnection('localhost', 5672, 'guest', 'guest') opens the connection. The four arguments are the host, the port (5672 is AMQP's default), and the username and password. guest/guest is RabbitMQ's built-in default account.
• $connection->channel() opens a channel. This is the object you'll call queue_declare, basic_publish and basic_consume on for the rest of the chapter.
• $channel->close() and $connection->close() release the resources when you're done. Always close them, in that order: channel first, then connection.

Run the script with php your-file.php. If it prints Connected to RabbitMQ and exits cleanly, your client and broker are talking.

Form one habit now. Opening a connection is expensive, since it's a TCP handshake followed by an AMQP handshake, while opening a channel on top of it is cheap. Real apps hold a single long-lived connection and open channels as they go, rather than reconnecting for every message.

Common mistake

The guest account only works over a localhost connection. That's a RabbitMQ security default: guest/guest is refused from any remote host. On your own machine it's fine, but the moment RabbitMQ lives on another server you'll need to create a real user (covered later in the course) - otherwise you'll get an "ACCESS_REFUSED" error even though the password is correct.

FAQ

What's the difference between AMQPStreamConnection and AMQPSocketConnection?

Both open a connection. AMQPStreamConnection uses PHP's stream functions and is the default choice for almost everything - use it unless you have a specific reason not to. AMQPSocketConnection uses the sockets extension and can be marginally faster for high-throughput publishing, but it behaves slightly differently around timeouts.

Do I need the RabbitMQ server installed to use php-amqplib?

You need a broker running somewhere the client can reach - it doesn't have to be on the same machine. Running it locally with Docker is the easiest way while you learn.

Why port 5672?

That's the default TCP port for AMQP, the protocol RabbitMQ uses for messaging. It's a different port from the management UI (15672), which is a web dashboard, not the messaging channel.