Pour l'explication de IsClientConnected tire des MSDN :
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IsClientConnected
The IsClientConnected property is a read-only property that indicates if the client has disconnected from the server.

Syntax
Response.IsClientConnected ( )



Remarks
This property allows you greater control over circumstances where the client may have disconnected from the server. For example, if a long period of time has elapsed between when a client request was made and when the server responded, it may be beneficial to make sure the client is still connected before continuing to process the script.

Example
<%
'Check to see if the client is connected.
If Not Response.IsClientConnected Then
'Get the sessionid to send to the shutdown function.
Shutdownid = Session.SessionID
'Perform shutdown processing.
Shutdown(Shutdownid)
End If
%>

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Pour ton cas, je sais po si ca va resoudre ton probleme ca.
Tu ne peux de toute facon po savoir si le client a quitter brutalement. D'apres moi, uniquement le timeout fait son boulot ...

Br@scoo