how we can process data in rabbitmq single message as well as collection of data

In this example we are processing each type of message one by one. So you can see how data gets processed.

<?php
require 'connection.php';


try {
    $channel = new AMQPChannel($connection);
    $exchange = new AMQPExchange($channel);
    $exchange->setName('Test1');
    $exchange->setFlags(AMQP_DURABLE);
    $exchange->setType(AMQP_EX_TYPE_DIRECT); // Set the exchange type to 'direct'


    $data = [
        "data for routing key a " . time(),
        "data for routing key a " . time(),
        "data for routing key a " . time(),
        "data for routing key a " . time(),
    ];


    $data2 = [
        "data for routing key b " . time(),
        "data for routing key b " . time(),
        "data for routing key b " . time(),
        "data for routing key b " . time(),
    ];


    if (!empty($data)) {
        foreach ($data as $message) {
            $exchange->publish($message, 'routing_key_A');
        }
    }


    if (!empty($data2)) {
        foreach ($data2 as $message2) {
            $exchange->publish($message2, 'routing_key_B');
        }
    }
} catch (AMQPConnectionException | AMQPExchangeException | AMQPChannelException $e) {
    var_dump($e->getMessage());
}

Now in case you want to process whole array instead of each message at a time. you can change your code as given below.

<?php
require 'connection.php';


try {
    $channel = new AMQPChannel($connection);
    $exchange = new AMQPExchange($channel);
    $exchange->setName('Test1');
    $exchange->setFlags(AMQP_DURABLE);
    $exchange->setType(AMQP_EX_TYPE_DIRECT); // Set the exchange type to 'direct'


    $data = [
        "data for routing key a " . time(),
        "data for routing key a " . time(),
        "data for routing key a " . time(),
        "data for routing key a " . time(),
    ];


    $data2 = [
        "data for routing key b " . time(),
        "data for routing key b " . time(),
        "data for routing key b " . time(),
        "data for routing key b " . time(),
    ];


    if (!empty($data)) {
        $exchange->batchPublish($data, 'routing_key_A');
    }


    if (!empty($data2)) {
        $exchange->batchPublish($data2, 'routing_key_B');
    }


    // Publish all messages in the batch
    $exchange->publishBatch();
} catch (AMQPConnectionException | AMQPExchangeException | AMQPChannelException $e) {
    var_dump($e->getMessage());
}

Hope this guide helps