"Octavian Rasnita" <orasnita@stripped> wrote on 07/28/2005 02:18:05 PM:
> Hi,
>
> I am using a MySQL database on a web site, and I would like to know what
> happends if someone searches in the database using a form, but after a
few
> seconds MySQL starts the query, that user hit the "Stop" button of the
> browser.
> Will MySQL continue its searching and also create the cache, or it will
stop
> automaticly?
>
> If it will also stop, can I do something to let it continue searching in
> order to create the cache and the next time another visitor searches for
the
> same thing it will get the results from the cache?
>
> Sorry if this is a stupid question and thank you very much.
>
> Teddy
>
Here is what happens with nearly all web requests:
1) The browser (or some other tool) sends a message to a web server to get
something. This usually because the user specifically asked for something,
because an HTML page has tags in it for other content (like images), or by
some other user action or client-side programming. Because you are
specifically asking for "something" from the server, the specially
formatted request is called either a Uniform Resource Locator (URL) or, in
a more general sense, a Uniform Resource Identifier (URI).
2) the web server receives the URI and begins the process of providing
what was requested. In the case of a scripted response, like your example,
it make take some time for the server to complete assembling it's
response.
3) the server responds with data/the browser receives the data. (Hopefully
the browser will know what to do with whatever it asked for.)
In your sample scenario, you said that between steps 2 and 3:
2.5) user clicks "STOP" in the browser.
There aren't any messages in most of the internet protocols (HTTP, FTP,
GOPHER, WAIS, etc) to cancel a response. The simplest thing for to do was
to just ignore the response if it ever came.
So to answer your question, the server doesn't know that the user is no
longer interested in the information so it continues to process the
request to its full and complete resolution. With some servers there are
ways to detect if the browser is maintaining an open connection with the
server (waiting on a response) but most server-side scripts do not check
that status. Because they don't check that status, the script will not
detect that the user has "hung up" waiting on it's response until it is
ready to send the actual response data. The query completes, the cache is
filled, and whatever effort went into formatting the response is just
wasted. Since the user doesn't want it, the response is sent to the bit
bucket.
Make sense?
Shawn Green
Database Administrator
Unimin Corporation - Spruce Pine
