Comet: practical solution or crutch?

With the complexity of web applications ever increasing, developers have run into problems caused by limitations in the design of HTTP. In particular, HTTP was designed for servers to transmit data only if clients request it (client pull). However, in web applications there also are scenarios where information becomes available on the server more or less in realtime, with no means of pushing these to the client.

The conventional way of collecting this information is for the client to continuously request the latest information (polling). This may saturate the server with requests, while the information received by the client is most likely outdated. Comet is a term used to describe techniques to work around this limitation, allowing the server to push data to the client at the moment it becomes available. While Comet meets the needs of application designers, it is not without its consequences for both developers and systems administrators. This presentation will illustrate how Comet works, and discuss its advantages and limitations.