  Ajax applications are designed to have high user interactivity and low
user-perceived latency. Real-time dynamic web data such as news headlines,
stock tickers, and auction updates need to be propagated to the users as soon
as possible. However, Ajax still suffers from the limitations of the Web's
request/response architecture which prevents servers from pushing real-time
dynamic web data. Such applications usually use a pull style to obtain the
latest updates, where the client actively requests the changes based on a
predefined interval. It is possible to overcome this limitation by adopting a
push style of interaction where the server broadcasts data when a change occurs
on the server side. Both these options have their own trade-offs. This paper
explores the fundamental limits of browser-based applications and analyzes push
solutions for Ajax technology. It also shows the results of an empirical study
comparing push and pull.
