Question

How do i measure how long a client has to wait for a request.

On the server side it is easy, through a filter for example. But if we want to take into accout the total time including latency and data transfer, it gets diffcult.

is it possible to access the underlying socket to see when the request is finished? or is it neccessary to do some javascript tricks? maybe through clock synchronisation between browser and server? are there any premade javascripts for this task?

Answer 1

There’s no way you can know how long the client had to wait purely from the server side. You’ll need some JavaScript.

You don’t want to synchronize the client and server clocks, that’s overkill. Just measure the time between when the client makes the request, and when it finishes displaying its response.

If the client is AJAX, this can be pretty easy: call new Date().getTime() to get the time in milliseconds when the request is made, and compare it to the time after the result is parsed. Then send this timing info to the server in the background.

For a non-AJAX application, when the user clicks on a request, use JavaScript to send the current timestamp (from the client’s point of view) to the server along with the query, and pass that same timestamp back through to the client when the resulting page is reloaded. In that page’s onLoad handler, measure the total elapsed time, and then send it back to the server – either using an XmlHttpRequest or tacking on an extra argument to the next request made to the server.