Displaying Advertisements
| The AdRotator control enables you to randomly display different advertisements in a page. You can store the list of advertisements in either an XML file or in a database table. The AdRotator control supports the following properties (this is not a complete list):
The AdRotator control also supports the following event:
Notice that the AdRotator control includes a KeywordFilter property. You can provide each banner advertisement with a keyword and then filter the advertisements displayed by the AdRotator control by using the value of the KeywordFilter property. This property can be used in multiple ways. For example, if you are displaying more than one advertisement in the same page, then you can filter the advertisements by page regions. You can use the KeywordFilter to show the big banner advertisement on the top of the page and box ads on the side of the page. You can also use the KeywordFilter property to filter advertisements by website section. For example, you might want to show different advertisements on your website's home page than on your website's search page. Note If you cache a page that contains an AdRotator control, then the AdRotator control is excluded from the cache. In other words, even if you cache a page, randomly selected banner advertisements are still displayed. The AdRotator control takes advantage of a new feature of the ASP.NET 2.0 Framework called post-cache substitution. You learn more about this feature in Chapter 23, "Caching Application Pages and Data." Storing Advertisements in an XML FileYou can store the list of advertisements that the AdRotator displays in an XML file by setting the AdRotator control's AdvertisementFile property. For example, the page in Listing 4.11 contains three AdRotator controls that retrieve banner advertisements from an XML file named AdList.xml (see Figure 4.8). Listing 4.11. AdRotatorXML.aspx
Figure 4.8. Displaying advertisements from an XML file. The page in Listing 4.11 contains an AdRotator control that displays a banner advertisement at the top of the page. The page also contains two AdRotator controls that display box advertisements on the right of the page. Notice that the first AdRotator has a KeyworldFilter property that has the value banner, and the remaining two AdRotator controls have KeywordFilter properties with the value box. The first AdRotator displays only banner advertisements, and the remaining two AdRotator controls display only box advertisements. All three AdRotator controls get their list of banner advertisements from a file named AdList.xml. This file is located in the App_Data folder for security reasons. The files in the App_Data folder cannot be opened in a web browser. Note There is nothing wrong with assigning different XML files to different AdRotator controls. For example, you could create distinct BannerAd.xml and BoxAd.xml files and then you would not have to worry about the KeywordFilter property. The file in Listing 4.12 contains the contents of the AdList.xml file. Listing 4.12. AdList.xml
The Impressions attribute in the file in Listing 4.12 determines how often each banner advertisement is displayed. For example, the first banner advertisement is displayed 50% of the time, and the remaining two banner advertisements are displayed 25% of the time. Storing Advertisements in a Database TableRather than store the list of advertisements in an XML file, you can store the list in a database table. For example, the AdRotator control contained in Listing 4.13 is bound to a SqlDataSource control. The SqlDataSource control represents the contents of a database table named AdList, which is located in a SQL Express database named AdListDB. Listing 4.13. AdRotatorDatabase.aspx
To use the page in Listing 4.13, you need to create the AdList database table. This table has the following schema:
Notice that the columns in the AdList database table correspond to the attributes in the AdList.xml file discussed in the previous section. Tracking Impressions and TransfersNormally, when you are displaying advertisements, you are doing it to make money. Your advertisers will want statistics on how often their advertisements were displayed (the number of impressions) and how often their advertisements were clicked (the number of transfers). To track the number of times that an advertisement is displayed, you need to handle the AdRotator control's AdCreated event. To track the number of times that an advertisement is clicked, you need to create a redirect handler. Warning If you create an event handler for the AdCreated event and you cache the page, the content rendered by the AdRotator control will also be cached. When handling the AdCreated event, use partial page caching to cache only part of a page and not the AdRotator control itself. The page in Listing 4.14 displays a banner advertisement with the AdRotator control. The page includes an event handler for the AdRotator control's AdCreated event. Listing 4.14. AdRotatorTrack.aspx
The AdCreated event handler does two things. First, it inserts a new record into a database table named AdStats, which records an advertisement impression. Second, the handler modifies the NavigateUrl so that the user is redirected to a handler named AdHandler.ashx. The AdStats database table looks like this:
The Type column is used to record the type of entry. The value 0 represents an advertisement impression, and the value 1 represents an advertisement transfer. When you click an advertisement, you link to a file named AdHandler.ashx. This file is contained in Listing 4.15. Listing 4.15. AdHandler.ashx
The handler in Listing 4.15 performs two tasks. First, it inserts a new record into the AdStats database table, recording the fact that a transfer is taking place. Next, it grabs the NavigateUrl from the AdList database table and sends the user to the advertiser's website. The final page displays advertiser statistics from the AdStats database table (see Figure 4.9). This page is contained in Listing 4.16. Figure 4.9. Displaying advertiser statistics. Listing 4.16. AdRotatorStats.aspx
The page in Listing 4.16 contains two GridView controls bound to two SqlDataSource controls. The first GridView displays statistics on impressions, and the second GridView displays statistics on transfers. |
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