Het Open Web
Oktober 29, 2009

Comet: practical solution or crutch?

By Joor Loohuis.


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 This may saturate the server with requests, while the information received by the client is most likely outdated.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.


1995-2000: researcher in the Geophysics group of the Department of Earth Sciences at Utrecht University.

1999-2000: Linux and Open Source consultant at Cap Gemini, working on various projects

2000-present: owner/manager of Loco (Loohuis Consulting), a consultancy firm in Utrecht specializing in custom webhosting, Web 2.0 solutions, and GPL compliance engineering.

Najaar 2009

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