Sometimes it is important to be able to wait a short period of time in an ASP or VB application before continuing on. Most recently, I had to write an application that used Site Server content replication to migrate files from one folder to another. In order to ensure that the process completed successfully, I had to check the process's status periodically and wait for it to either fail or succeed. Obviously, I could have done a WHILE ERR<>0...WEND loop, but that would have been unnecessarily harsh on the cpu -- I really don't need to check the status of the process a thousand times per second.

So, this component, Timer.Sleep, uses the windows kernel Sleep command, and is only a few lines of code. It has one method, DoSleep, which takes one parameter, the number of milliseconds to sleep. You can download the component DLL here: Timer.dll (20k)

The source code for the example is:

1    <% OPTION EXPLICIT %> 2    <% 3    'Try to avoid buffering and caching... 4    Response.Buffer = False 5    Response.Expires = 0 6    Response.ExpiresAbsolute = Now() - 1 7    Response.AddHeader "cache-control", "private" 8    Response.AddHeader "pragma", "no-cache" 9    Server.ScriptTimeout = 0 10   %> 11   <!-- #INCLUDE VIRTUAL="/stevesmith/include/articleformat.asp" --> 12   <!-- #INCLUDE VIRTUAL="/stevesmith/include/DisplayStatusMessage.asp" --> 13   <% 14   Response.Write("This example is no longer supported - the COM object is no longer installed on this server.") 15   Response.End 16   'Declare Variables 17   Dim objTimer 18   Dim I 19   Dim strCountdown 20    21   'Instantiate components 22   Set objTimer = Server.CreateObject("Timer.Sleep") 23    24   'Display top of page template 25   Call ArticleHeader("Sleep/Timer Example","","") 26   %> 27   <p> 28   <b>Look at your status bar at the bottom of your browser.</b> 29   </p> 30   <p>This is a very simple example that demonstrates the use of the timer 31   dll. We're going to be writing to the status bar of your browser, once per second, 32   with a countdown. 33   </p> 34   <p> 35   <b>Note:</b> 36   If your browser is set up to cache web pages, you may not see the countdown take place 37   after your first visit to this page. 38   </p> 39   <% 40    41   'Display bottom of page template 42   Call ArticleFooter() 43    44   'Count down from 10 to 0, then display LIFTOFF in the status window 45   For I = 10 To 0 Step -1 46    Call objTimer.DoSleep(1000) 47    strCountdown = strCountdown & I & "... " 48    If I = 0 Then 49    strCountdown = strCountdown & " LIFTOFF!!!" 50    End If 51    DisplayStatusMessage(strCountdown) 52   Next 53   %>

The included file that writes to the status window is documented here:

1    <% 2    Public Sub DisplayStatusMessage(strMessage) 3     Dim NL 4     NL = chr(10) & chr(13) 5     Response.Write "<script type=" & Chr(34) & "text/javascript" & Chr(34) & ">" & NL 6     Response.Write "<!--" & NL 7     Response.Write "parent.window.status = '" & strMessage & "';" & NL 8     Response.Write "//--></script>" 9    End Sub 10   %>