Simple Banner Rotation Using Active Server Pages
Editorial Note: Since this article was published, technologies have moved on, as they always do. ASP is now generally referred to as Classic ASP. The preferred Microsoft web tecnology is now ASP.NET. Follow this link for an updated article that shows how to handle banners in ASP.NET.

Your web site is receiving an ever-increasing amount of traffic from users interested in your content. Now you'd like to capitalize on the traffic and make some money from advertising. Due to the highly focused nature of your site's content, you've even been able to get some companies to give you banners to display.

Now what?

Basically, you need to be able to display banners on your web pages, without having to manually edit every web page that comprises your site. Additionally, you'd like to have a way to automatically rotate the banners, and even control how often some of the banners display.

Using Active Server Pages (ASP), this can easily be accomplished. ASP is a technology supported by Microsoft's Internet Information Server (IIS), one of the most common web servers around.

ASP is a server-side technology, which means that programmers include code in their web pages mixed in with HTML. The web server ensures that the ASP code is executed on the server, before the HTML page is sent back to a user's browser. When executed, the ASP code can write out HTML content, which will be sent back to the browser as part of the HTML page. Thus, ASP code can select a banner to be displayed and output the necessary HTML to display it.

Ad Rotator Component

One of the standard components provided by ASP is the Ad Rotator. This component will display a different banner each time a web page is displayed. The Ad Rotator depends on a configuration file, referred to as a rotator schedule file, to specify the banners that will be displayed, as well as any other information that is required.

When a banner is clicked on, the user is sent to a redirection page. This page receives information about the click, including the specific banner image that was clicked on and the destination URL.

This page is expected to record information about the click-through, if desired, and then redirect the users to the expected web page. This redirection will, of course, be entirely transparent to any users.

Rotator Schedule File

For each banner, the Ad Rotator needs to know the following things:

  • The location of the banner image.
  • The destination to go to when the banner is clicked.
  • The size (width and height) of the banner.
  • The alternate text to be displayed if the user hovers their mouse over the banner.
  • How often the banner should be displayed.

This information is recorded in a configuration file known as a rotator schedule file. A sample file is shown in Listing 1.

Listing 1: Rotator Schedule File

REDIRECT redirect.asp
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The file begins with a global section that applies to all banners listed in the file. The line with the asterisk ends the global section. The REDIRECT field tells the Ad Rotator where to go to when the banner is clicked. The WIDTH and HEIGHT fields define the size of the banner, while the BORDER field indicates the width of the border that should be displayed around the banner (with zero indicating no border at all).

This is followed by a series of lines describing banners that will be displayed by the Ad Rotator. For each banner, the first line indicates where the banner image can be found. The second line shows the destination URL for the banner. The next line provides alternate text to be displayed if the banner cannot be shown (i.e. - if a user has a text-only web browser or is surfing with graphics turned off). Most browsers will also show this text if the user simply hovers their mouse over the banner.

The final number shown for each banner is the relative weight, which governs how often a banner will be shown in comparison to other banners in the file. In the example, the weight of the first banner is twice that of the second banner, so the Microsoft banner will be displayed twice as often.

Displaying a Banner Using the Ad Rotator

The code to display a banner is straightforward, as shown in Listing 2. Simply create an instance of the Ad Rotator object. Then call the GetAdvertisement method, passing in the location of the rotator schedule file. The function returns the necessary HTML to display the banner, which is then immediately written out and sent back to the user's browser.

This code could be added to every page that displays a banner. More likely, though, an enterprising programmer would incorporate this code into web pages via a server-side include.

Listing 2: Displaying a Banner

Dim objAdrot
'---- Create the component
Set objAdrot = Server.CreateObject("MSWC.AdRotator")
'---- Get the ad from the rotator schedule file and write out the infor
Response.Write objAdrot.GetAdvertisement("/banners_468_60.txt")
'---- Destroy the object
Set objAdrot = nothing

Handling the Redirection

The redirection file receives two parameters, the URL of the destination and the name of the banner file. Generally, the second is not used. Listing 3 shows the ASP code that redirects the user to the desired destination.

The redirection file could, of course, do much more than this. For example, it could store information about banner click-throughs in a database.

Listing 3: Redirection File

Response.Redirect Request.QueryString("URL")


Microsoft's Ad Rotator component, which is an integral part of ASP, provides an easy way to add rotating banners to a web site. While the component has limited functionality compared to sophisticated commercial advertisement management systems, it nevertheless represents a free and effective way to add advertising capabilities to web sites, particularly for smaller businesses.


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