Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Wed, 22 Jun 2005 15:23:06 +0200

On Wednesday 22 June 2005 14:47, Dalesio, Leo `Bob` wrote:
> >From a functional point of view - the DA approach gives you total
> > flexibility.
>
> What does it do to the complexity of the implementation and the
> performance? Does it have an impact on the server? Or just the client
> side?

It depends. The more primitive types your language supports, the less 
work the DA-CA-bridge has to do converting.

For instance, a native Java server would have to convert requests for 
unsigned types on the server side. A Perl client will probably have to 
do a lot of work in order to convert Perl scalar values to whatever is 
appropriate, taking the server's native type into consideration. 
Similar for most untyped or dynamically types languages.

OTOH, IOCs are probably /not/ going to be implemented in Java. Or Perl 
or Haskell ;-)). And /if/ they are, we will have more severe problems 
with efficiency than those caused by network-native type conversion!

A C/C++ server need not convert primitive types. Regarding complex 
(composite) types, I suggest interfaces should be designed to allow 
efficient implementation in C/C++, as has been the goal with the 
current DA proposal, IIRC.

Ben

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System