HOWTO: Use IsClientConnected to Check If Browser is Connected
ID: Q182892
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The information in this article applies to:
-
Microsoft Visual InterDev, versions 1.0, 6.0
-
Active Server Pages
SUMMARY
When a browser requests an Active Server Pages (ASP) page from the server,
but does not wait for the entire page to be downloaded, the server
continues to process the request, wasting CPU cycles. However, in Internet
Information Server (IIS) 4.0, you can use the Response.IsClientConnected
property to determine if the browser is still connected, and if not, to
cease processing the ASP page to conserve CPU cycles.
MORE INFORMATION
Below, is a sample ASP page that demonstrates one application of the
IsClientConnected property.
WARNING: ANY USE BY YOU OF THE CODE PROVIDED IN THIS ARTICLE IS AT YOUR OWN
RISK. Microsoft provides this code "as is" without warranty of any kind,
either express or implied, including but not limited to the implied
warranties of merchantability and/or fitness for a particular purpose.
<%@ LANGUAGE="VBSCRIPT" %>
<%
'
' !!! WARNING !!!
'
' This page has code in it that may use 100% CPU cycles for at least
' 30 seconds. Do not run this code on a production server, restrict
' its use to a test server.
'
Function IsConnectedAfter(Seconds)
Dim StartTime 'time the function started
Dim PauseTime 'time the pause loop started
' Use PerfMon to monitor the CPU cycles on the Web server. You
' will notice that if you click stop in the browser, the CPU
' will settle down sooner than if the loop had continued.
IsConnectedAfter = True
StartTime = Now
Do While DateDiff("s", StartTime, Now) < Seconds
PauseTime = Now
Do While DateDiff("s", PauseTime, Now) < 1
'Do Nothing
Loop
Response.Write "."
If Response.IsClientConnected = False then
IsConnectedAfter = False
Exit Function
End If
Loop
End Function
%>
<HTML>
<HEAD>
<META NAME="GENERATOR" Content="Microsoft Visual InterDev 1.0">
<META HTTP-EQUIV="Content-Type" content="text/html; charset=iso-8859-1">
<TITLE>Document Title</TITLE>
</HEAD>
<BODY>
<h1>!!! WARNING !!!</h1>
<p>This page has code in it that may use <b>100% CPU cycles</b>
for at least 30 seconds. Do not run this code on a production
server, restrict its use to a test server.
<p>Use PerfMon to monitor the CPU cycles on the Web server.
Press STOP in the Web browser, and you will see that the
CPU cycles will settle down sooner than they would have
without checking the IsClientConnected property.
<HR>
<%
If IsConnectedAfter(30) then
Response.Write "<p>The client is still connected</p>"
Else
'The browser is no longer connected. This would be a
'good place to abort any transactions, clean up any
'variables, and so forth.
End If
%>
</BODY>
</HTML>
REFERENCES
For the latest Knowledge Base articles and other support information on
Visual InterDev and Active Server Pages, see the following page on the
Microsoft Technical Support site:
http://support.microsoft.com/support/vinterdev/
Additional query words:
Keywords : kbASP kbVisID kbVisID100 kbVisID600 kbWebServer kbGrpASP VIServer VIScripting
Version : WINDOWS:1.0,6.0; winnt:
Platform : WINDOWS winnt
Issue type : kbhowto