Re: V4 design issue: Should primitive data types have well defined precisions?

[Ralph Lange <Ralph.Lange@bessy.de>]

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?
>  
I'm amused to see that we start discussing basic requirements and 
properties of an introspective data interface again. I thought this 
discussion was held and ended five years ago. Well....

You won't get higher flexibility and introspection without making the 
implementation and interface more complex. In a similar fashion, 
accessing predefined fixed data types will of course always be faster 
than using an introspective way to access data. So - yes, the 
implementation and the interface will be more complex.

For V3 all conversions were done in the CA server. V4 will move (almost) 
all conversion work into the client, making the memory and cpu footprint 
on the IOC generally smaller - this could partly be compensated by the 
use of C++, probably more for the memory than for the cpu load.

For performance measurements using an older version of DataAccess see 
the papers that Jeff and I were presenting at the ICALEPCS 2001 
(http://arxiv.org/abs/cs.ni/0111026 and http://arxiv.org/abs/cs.se/0111036)

Ralph