Pushing results from RabbitMQ queue to CakePHP frontend

Question

I'm developing a system consisting in frontend built in CakePHP framework and Java based backend. The communication between this two ecosystems is carried out by sending JSON messages from CakePHP controller to RabbitMQ broker. When message is consumed, the result is being send back to the frontend. Now, I need to consume the message and push the result from the controller to user browser. For the PHP part I'm using a phpamqplib, but it needs to have an infinite loop when listening for new messages:

     $channel->basic_consume('AMQP.COMMAND.OUTPUT.QUEUE', 
            'consumer', 
            false, 
            false, 
            false, 
            false, 
            array($this, 'processMessage'));


    function shutdown($ch, $conn){
        $ch->close();
        $conn->close();
    }
    register_shutdown_function('shutdown', $channel, $conn);

    while (count($channel->callbacks)) {
        $read   = array($conn->getSocket()); // add here other sockets that you need to attend
        $write  = null;
        $except = null;
        if (false === ($num_changed_streams = stream_select($read, $write, $except, 60))) {
            /* Error handling */
        } elseif ($num_changed_streams > 0) {
            $channel->wait();
        }
    }

In my controller this is provoking Apache Server to throw an error because maximum execution of 30 seconds is exceeded. I really need help here. What's the best solution to listen for new messages and then pushing the result to the view?

Thanks

Cheers.

Answer 1

I highly recommend converting this to an AJAX-based infrastructure, and re-factor your code to do this:

1. CakePHP makes an AJAX call to load the page every x seconds
2. The AJAX URL gets the remaining elements from the queue, and outputs them

Your code doesn't look complete, so I can't refactor it completely, but you could change the AJAX URL to do something like this:

if (count($channel->callbacks)) {
    $read   = array($conn->getSocket()); // add here other sockets that you need to attend
    $write  = null;
    $except = null;
    if (false === ($num_changed_streams = stream_select($read, $write, $except, 60))) {
        /* Error handling */
    }
}

and close the channel when done.

Your other option, if you really want to use push, is to use web sockets. Do a search, or this tutorial might help you get started.