class Comm;
using CommPtr = boost::intrusive_ptr<Comm>;
class Engine;
+class Exec;
+using ExecPtr = boost::intrusive_ptr<Exec>;
class Host;
class Link;
class Mailbox;
using MailboxPtr = boost::intrusive_ptr<Mailbox>;
class Mutex;
class NetZone;
-
+class VirtualMachine;
class File;
class Storage;