Example on how to set expiration time on Microsoft.Practices.EnterpriseLibrary.Caching cache.

public class CacheRefreshAction : ICacheItemRefreshAction{

    {
     public void Refresh(string key, object expiredValue, CacheItemRemovedReason removalReason)           // Nothing is done in this Class. It must exist to be able to set a Exoiration time on the PageCache.Add method.     }
 }
.
.
.

source = oFacade.GetUserRoles(ident.Name);

SecurityFacade oFacade = new SecurityFacade();this.PageCache.Add("Roles" + Context.User.Identity.Name, source, CacheItemPriority.Normal,new CacheRefreshAction(), new AbsoluteTime(DateTime.Now.AddMinutes(20)));Example how to set exiration time to 20 minutes: