How does realtime messaging compare with AJAX?

AJAX is a method for data queries while realtime messaging is a method for data push. You can use both AJAX and realtime data push. Use AJAX to have your applications ask questions (queries). Use PubNub real-time messaging to directly and dynamically push data to one or millions of mobile and web devices.

For Example, Skype and WebEx would use PubNub's realtime data stream service for chat messages and device signaling (making the phone ring) while authentication (user login) and data save queries still occur over AJAX-like interfaces. In summary, AJAX and realtime data stream messaging can be viewed as two separate engines; both usable in combination to carry out push and query functionality.