Re: Network Accessable Types

[Kay-Uwe Kasemir <kasemirk@ornl.gov>]

On Jul 26, 2005, at 05:49, Ralph Lange wrote:
> 1. Learning the native type of data is part of the DA interface. The 
> DA interface is purely about data and does not have any notion of 
> network transport. An application may access things within a library 
> or through shared memory using DA without any network involved.
I agree, and if you do,
doesn't it follows that the application
shouldn't have to deal with
possible network buffer boundaries?
The application should see a data interface
that allows random access:
List the properties,
learn that the 5th property is the "value",
typed as some sort of number, then fetch it as a double.
Ask for the "units" property as a string, ...

The V3 channel access library does hide the network
delays and buffer boundaries from me,
I eventually get the full DBR_CTRL_XXX
and can access any piece in there in random order.
(Yes, it requires pre-configuration of the max. array size)

Why should the new data access interface
involve the application in the handling of the
incoming network stream byte-by-byte,
maybe first receiving the time stamp,
then a few initial characters of a string value,
then the next 2 chars, ...?

Thanks,
-Kay