Asp.NET - Multiple Instances of AdRotator - asp.net

Question

I've created a master page that uses 3 instances of System.Web.UI.WebControls.AdRotator each backed by the same XML file of ad elements. For example,
<asp:adRotator AdvertisementFile="/ads.xml" Runat="server"/>
*** ads.xml ***
<Advertisements>
<Ad>
<ImageUrl>/Path/Banner.gif</ImageUrl>
<NavigateUrl>http://www.google.com</NavigateUrl>
<AlternateText>
The best search engine in the world!
</AlternateText>
<Impressions>3</Impressions>
</Ad>
</Advertisements>
The problem is on occasion the same ad will appear in 2 or more of the AdRotators at a given instant.
What's the best way to make the ads presented at any given time unique? One possibility is to separate the ads into 3 distinct XML files and assign each AdRotator a different file. However, that leads to a given ad always being in the same location that may or my not be the "premium" location on the page.

Answer 1

AdRotator wasn't designed to display a series of banners, so you can't prevent duplicates if you place multiple AdRotator controls on a Web Form and point them to the same AdvertisementFile.
The AdRotator is only designed to serve the most basic ad functionality. It's definitely not intended to compete with or replace a "real" ad-serving system. If you need anything more elaborate, you'll need to look into a third-party system or roll your own.

Answer 2

Although I second Rex M's recommendation of rolling out your own AdRotator because of its inherent limitations, there is a way to do this within the AdCreatedEvent of the rotator. For 3 or more rotators try the concept outlined at http://tinyurl.com/7rymect (must scroll to bottom of page to see answer). Otherwise, you could try something along these lines with 2 AdRotators on the page:
/// <summary>
/// First ad rotator control
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
protected void AdRotator_AdCreated(object sender, AdCreatedEventArgs e)
{
//Get displayed ad's id
int currentAd = (int)e.AdProperties["AdId"];
//Remove that ad from the list
TList<Banner> ads = GetBannerThatIsNotThisAdId(currentAd, AdRotator.KeywordFilter);
//Do we have an ad to display?
if (ads.Count > 0)
{
AdRotator1.DataSource = ads;
AdRotator1.DataBind();
}
else //nope, so hide 2nd control
{
AdRotator1.Visible = false;
}
}
public static TList<Banner> GetBannerThatIsNotThisAdId(int adId, string pCategory)
{
BannerService bannerService = new BannerService();
TList<Banner> banners = bannerService.GetAll();
Banner banner = bannerService.GetByAdId(adId);
banners.ApplyFilter(delegate(Banner b) { return b.Keyword.Equals(pCategory) && (b.IsActive.Equals(true)); });
banners.Remove(banner);
return banners;
}