Re: Why we can't provide a null parameter to method in CORBA?

CORBA allows you to pass an empty string.

Passing 'null' means you don't want to send data. If you don't want to
pass data, there is no reason to specify parameters.
What you actually want is 2 functions:
         string echoString(in string mesg);
and another
         void echoString();
Unfortunately, CORBA does not allow overloading (to allow mappings to
programming languages with this limitation)

Further, since the string is passed by value (deep copied) you can not
pass 'null'.