So, you want to keep track of the people who've visited your site, eh? This article describes how to build a hit counter which keeps track of the number of visitors to your site. The idea is rather simple: whenever a new visitor comes, increment some sort of counter.
Well, you'll be happy to hear that ASP provides many of these mechanisms inherently. Application level variables, as previously described in other 4Guys articles, are variables that persist from the starting of the webserver to the shutting down of the webserver. The ideal place for our counter, then, is as an application-level variable. ASP also provides us with a mechanism to let us know when a new user hits our website. Whenever a new visitor comes to your site, the event Session_OnStart is fired in your global.asa file.
So, let's see how we could set up a nifty counter. All of our counting work will be done in our global.asa file. Let's look at the code for global.asa:
<SCRIPT RUNAT="Server" LANGUAGE="VBScript">
'Lock the Application for concurrency issues
'Increment the counter
Application("Hits") = Application("Hits") + 1
'Unlock the Application
'This variable Hits will store the # of visitors
Application("Hits") = 0
'From the date stored in AsOfDate...
Application("AsOfDate") = Date
What this code is doing is when Application_OnStart fires (and it fires whenever the first visitor comes to your page after the server has last been bounced), we set out hit counter to 0 and store the value in Application("Hits"). We also create an Application-level variable called Application("AsOfDate") and set it to the current date.
Each time a new visitor visits our webpage, Session_OnStart is fired, and the Hits variable is incremented by one. To display our results, we should probably use an include file. Create a file named Hits.asp, and write the following code in it:
There have been <%=Application("Hits")%> since <%=Application("AsOfDate")%>
Now, in any ASP page where you want it to print out the number of hits, just include the following line of code:
A couple quick warnings about this hit systen... Anytime the server is rebooted, or the webserver is stopped and restarted, your hit counter will be reset. Also, to start hit counting for the first time, you will need to have the webserver stopped and restarted. This article discusses many topics covered in more detail in other articles. If you are confused about some of the terms, you should read some of the suggested article URLs below.
|Displaying the Hit Counter Results Graphically|
The script presented in this article displays the results from the hit counter as
simple HTML text. But wouldn't it be nice to display the results graphically, like:
times since December 1st, 2000
To learn how to do this, be sure to read: Representing Numbers Graphically!