Generic exception handler in service

Remoting SDK
1

Hi,

I use MadExcept for exception handling and am wandering how I can use that inside my implementation unit without having to code it in every procedure.

Thanks,

2

Hi,

You can create invoker’s descendant and put exception handling to it.

type
  TMyNewService_Invoker = class(TNewService_Invoker)
  protected
    procedure AfterInvoke(aMethodPtr: TMessageInvokeMethod;
      const anInstance: IInterface;
      const aFactory: IROClassFactory;
      const aMessage: IROMessage;
      const aTransport: IROTransport;
      anException: Exception); override; //<< check anException here
  end;
...

initialization
  fClassFactory_NewService := TROClassFactory.Create(__ServiceName, {$IFDEF FPC}@{$ENDIF}Create_NewService, TMyNewService_Invoker); //<<TNewService_Invoker replaced with TMyNewService_Invoker

check also TROInvoker.CustomHandleMessage implementation for understanding when AfterInvoke is called.

3

Thanks, this works perfect. I’m right to assume that just checking Assigned(anException) is the way to check an exception exists?

4

yes, you are right.

...
        AfterInvoke(mtd, instance, aFactory, aMessage, aTransport, nil);
      except
        on E: Exception do begin
          AfterInvoke(mtd, instance, aFactory, aMessage, aTransport, E); //<< you should catch this call only
5

Thanks, Evgeny!