You can extend the URL parser to accept additional properties or process additional tag expressions in order to provide information required by y our application to a JSP. For example, if a user qualifies for a promotion, an advertisement in the form of a media image displays on the product page. You may want to preview a product page when a given promotion is active. To do this, you add the ID of the promotion to the URL. For example:
promoId=$id
Then, you create a class that implements the atg.web.assetmanager.preview.PreviewURLParser interface and extends the following method:
public interface PreviewURLParser
{
public String parseURL(String pPreviewTemplateURL, Object pAsset, String
pProjectId) throws RepositoryException;
}