how the update messages in stack overflow site are being shown

Question

i would like to know how the update messages in this stack overflow site have been implemented.

To be more precise, for example while i am trying to reply for question and i am in the middle of typing my response, i will see a message on top of the page saying a new answer has been added. How is this feature has been implemented.

AFAIK, the possible way can be HTML5 websocket or serversocket technology. is there any other way to achieve this kind of push notification system especially using java, spring and jquery environment?

Not sure how to tag this question. correct the tags if i am wrong.

Answer 1

SO uses reverse ajax/comet technology to show those messages. I remember reading some discussion on meta about this feature, couldn't exactly find out the link for it at this moment. Will update as soon as I find.

Based on programming language framework name may change (websockets (or) socket.io etc.,), but at the end they all are from comet framework.

Update:

Here is SO meta discussion on this topic.