Adrotator control is available in ASP.Net to make the task of rotating the advertisement images in a web form quickly and easily. It also enables you to display different types of images whenever you refresh the page. Adrotator control takes the information about the images that are to be displayed from an XML file which also have many other elements in it that are used by this control.
First let us have a look at a sample advertisement file that is used by the adrotator control in ASP.Net.
Let us assume that the advertisement XML file is named as advt.xml. This file might look like,
<Advertisements>
<Ad>
<ImageUrl>site1img1.jpg</ImageUrl>
<NavigateUrl>http://www.site1.com</NavigateUrl>
<AlternateText>Site1 Main</AlternateText>
<Impressions>50</Impressions>
<Keyword>Product1</Keyword>
</Ad>
<Ad>
<ImageUrl>site2img2.jpg</ImageUrl>
<NavigateUrl>http://www.site2.com</NavigateUrl>
<AlternateText>Site2 Main Page</AlternateText>
<Impressions>75</Impressions>
<Keyword>Product2</Keyword>
</Ad>
</Advertisements>
The XML file that is used for advertisements would have the root element as the <Advertisements> element. This may have many <Ad> child elements. The elements <ImageUrl>, <NavigateUrl>, <AlternateText>, <Impressions> and <Keyword> are found in the <Ad> element. These elements identify the properties of the image that is displayed using the adrotator control.
The <ImageUrl> element specifies the path to the image that is displayed using the AdRotator control. Once a user clicks the image that is displayed the user is taken to the URL specified in the <NavigateUrl> element. The <AlternateText> element holds the text that is displayed when the image is not loaded. The text in this element is also used as a ToolTip in some of the browsers. The element <Impressions> has a number as a value. This number indicates how often the image is displayed with respect to other images. The more the value of the number in this element, the more is the frequency of the image that is displayed. The sum of all the impressions in the advertisement file should not exceed 2,047,999,999. Otherwise the AdRotator will throw an runtime exception. The element <Keyword> is used to give the category of the advertisement.
You can just drag and drop a AdRotator control in the webform and set its attributes if you are using Visual Studio .Net. The code that is generated for the AdRotator control might be something as given below:
<asp:AdRotator id="AdRotator1"
Target="_self"
AdvertisementFile="advt.xml"
runat="server"/>
In the above code in the HTML file you could see that the AdvertisementFile attribute of the AdRotator control has the xml file “advt.xml”. The other attributes are ‘id’ and ‘Target’. During runtime the AdRotator control uses the controls like <asp:HyperLink> and <asp:Image> to display the image in the web form page. The size of the image that is displayed is limited by the size of the AdRotator control that is found in the page. So, if you want to display larger images you need to adjust the size of the AdRotator control during design time itself.
It is possible to modify the values of the <ImageUrl>, <NavigateUrl> and <AlternateText> programmatically. For this you can use the AdCreated event. Thus by using the AdCreated event the rendering of the AdRotator control can be controlled.
<script runat="server">
Sub AdCreated_Event(sender As Object, e As AdCreatedEventArgs)
e.NavigateUrl = "http://www.yoursite.com"
End Sub
</script>
Using the above script you can modify the NavigateUrl property programmatically. This even is called in the AdRotator control as given below in the HTML code for the web form.
<asp:AdRotator id="AdRotator1" runat="server"
AdvertisementFile = "advt.xml"
Target="_self"
OnAdCreated="AdCreated_Event"/>
The OnAdCreated property of the AdRotator control specifies the event that is called which changes the URL to be navigated.
Thus the AdRotator control is an easy way to display and rotate advertisements and also to give preference to some advertisements by using the <Impressions> element of the advertisement XML file.
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