I need to write a notification system manager.

Here is my requirements:

I need to be able to send a Notification on different platforms, which may be totally different (for exemple, I need to be able to send either an SMS or an E-mail).

Sometimes the notification may be the same for all recipients for a given platform, but sometimes it may be a notification per recipients (or several) per platform.

Each notification can contain platform specific payload (for exemple an MMS can contains a sound or an image).

The system need to be scalable, I need to be able to send a very large amount of notification without crashing either the application or the server.

It is a two step process, first a customer may type a message and choose a platform to send to, and the notification(s) should be created to be processed either real-time either later.

Then the system needs to send the notification to the platform provider.

For now, I end up with some though but I don't know how scalable it will be or if it is a good design.

I've though of the following objects (in a pseudo language):

a generic Notification object:

class Notification {
    String                 $message;
    Payload                $payload;
    Collection<Recipient>  $recipients;
}

The problem with the following objects is what if I've 1.000.000 recipients ? Even if the Recipient object is very small, it'll take too much memory.

I could also create one Notification per recipient, but some platform providers requires me to send it in batch, meaning I need to define one Notification with several Recipients.

Each created notification could be stored in a persistent storage like a DB or Redis.

Would it be a good it to aggregate this later to make sure it is scalable?

On the second step, I need to process this notification.

But how could I distinguish the notification to the right platform provider?

Should I use an object like MMSNotification extending an abstract Notification? or something like Notification.setType('MMS')?

To allow to process a lot of notification at the same time, I think a messaging queue system like RabbitMQ may be the right tool. Is it?

It would allow me to queue a lot of notification and have several worker to pop notification and process them. But what if I need to batch the recipients as seen above?

Then I imagine a NotificationProcessor object for which I could I add NotificationHandler each NotificationHandler would be in charge to connect the platform provider and perform notification.

I can also use an EventManager to allow pluggable behavior.

Any feedbacks or ideas?

Thanks for giving your time.

Note: I'm used to work in PHP and it is likely the language of my choice.