Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Tue, 09 Aug 2005 09:56:50 +0200

Kay-Uwe Kasemir wrote:

Hi:

I think Ralph's recent answer with regard to the gateway already shows
that we can _not_ support all data types native to the machine
on which the client is run.

We have to agree on a limited set of types
because the gateway must understand all types
in order to compare the values against deadbands etc.

I'm happy to repeat once more:

There are _two_ type spaces [or whatever term is appropriate] connected

to this issue, which are _separate_.

1. One type space contains the fixed set of native "server-side" types

that Data Access is going to support when transporting stuff - across

language and machine borders. We have to define this type space,

together with a clever implementation of a type designator, that should

be comprehensive and easy-to-use. (Kay's further discussion is about

this type space.)

2. The other type space contains some (probably a subset) of the Data

Access implementation language's basic types. These are the types that a

user application will use to store the data, so Data Access will use

these types in the interfaces and will convert between the language and

platform independent fixed types (last paragraph) to the types of the

user's data (this paragraph).

It's not that difficult, is it?

Ralph

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System