Which technologies should I use for server-side programming?

I need to do server-side programming for some AJAX applications. Two main features that I need from these programs/technologies are:
1. Request to and response from the server side should be scalable depending on business logic.
2. Server side application should be able to send data in parts (for e.g. data for 2 out of 4 requests available, remaining data available after a minute) asynchronously.

I have Apache server installed on my system.