public interface IMyService extends IService {

  /**
   * @return
   * @throws org.eclipse.scout.commons.exception.ProcessingException
   */
  String getVersion() throws ProcessingException;
}

public class MyService extends AbstractService implements IMyService {

  @Override
  public String getVersion() throws ProcessingException {
    String version = "This String will be sent to the Client! Calculate the String from the SQL Service!";
    return version;
  }
}

    @Order(20.0)
    public class UpdateButton extends AbstractButton {

      @Override
      protected String getConfiguredLabel() {
        return TEXTS.get("Update");
      }

      @Override
      protected void execClickAction() throws ProcessingException {
        String dbVersion = SERVICES.getService(IMyService.class).getVersion();
        getVersionField().setValue(dbVersion);
      }
    }
  }