If you mean Apple Push Notification Server, you can read about it here:
http://en.wikipedia.org/wiki/Apple_Push_Notification_Service[
^].
I don't know exact same things in Microsoft or Google, but Google has push notification system in Chrome, and Microsoft has WNS:
https://msdn.microsoft.com/en-us/library/windows/apps/hh913756.aspx[
^].
It's possible that you mix up together different things: notifications for mail, Web
push technology, database notifications, and so on. That makes your question, as it is formulated, very vague and not answerable, but I would not say that the complex of problems you might want to raise are unrelated. Just the opposite: they are related and present a very important general problem of the past and contemporary computing.
Please see my past answers on the topic, where I try to explain the limitations of
client-server model,
pull technology, and explain importance of
push technology:
Application 'dashboard' for website accounts[
^],
How Do I Control My Client Computers By Server Computer[
^].
So, very basically, this is the thing: you can develop the system based on notifications and push technology, if you make network communication "custom enough". All you need it to get away from pure client-server model. It's not too far from high-level programming: you don't need to go to the levels lower than TCP. You can even use remoting or WCF. You did not bother to tell use your platform(s) and computer languages you want to use, so I cannot give you more detail in a short answer. Just in case, or for some general ideas, take a look at my past answers:
an amateur question in socket programming[
^],
Multple clients from same port Number[
^].
—SA
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