[ServiceContract(ConfigurationName="WebEntityService")]
[ServiceKnownType(typeof(WcfEntityService.TH.Category))]
public interface IEntityService {
    [OperationContract(IsOneWay=true)]
    void ScanEntity(ScanInfo scanInfo, WebEntityBase entity);
}

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
[KnownType(typeof(WcfEntityService.TH.Category))]
public class EntityService : IEntityService {
   [OperationBehavior(TransactionScopeRequired = true, TransactionAutoComplete = true)]
   public void ScanEntity(ScanInfo scanInfo, WebEntityBase entity) {
       try {
           WebScanner webScanner = new WebScanner(entity);
           webScanner.Scan(scanInfo);
           }
       catch (Exception ex) {
                throw;
            }
        }

[ServiceKnownType(typeof(WcfEntityService.TH.Category))]

namespace WcfEntityService.TH {
    [DataContract(IsReference = true)]
    public class Category : WebCategory, IWebEntity {
        public override void Processing(WebContent content, ScanInfo scanInfo) {
                //....
                ScanInfo categoryScanInfo = new ScanInfo(scanInfo);
                Category category = new Category();
                //....
                using (EntityServiceClient client =
                    new ("BasicHttpBinding_IEntityService ")) {
                    client.ScanEntity(categoryScanInfo, category);
                    client.Close();
                }
            }
        }