Ajax based application is growing too fast, many frequent requests have to handle by application servers. this overhead is really one of the big concern to maintain ajax based application.
more over reading the instance reply is one of the biggest challenge. as all requests are asychronizely processed, so ajax based application send request to application server more frequent that it actually needs.
the good example can be a chat application or a system where we have frequent request to sync with our messaging or notification service.
the basic process in continuation is to send delay response. for example –
i had a ajax request, which is intended for receiving a bunch of incoming message from my application server. so my request won’t get disconnected unless they really have some data to notify me. in between this time my request thread will be in suspended mode. obviously you can apply certain timeout period.
following diagram show how a request cycle works –
the following part shows the event model, which is used to wake up suspended request before it becomes dead and time out request.