Experimental Physics and
Industrial Control System

Kay-Uwe Kasemir <[email protected]> · Mon, 27 Jun 2005 15:03:19 -0400

On Jun 27, 2005, at 12:02, Marty Kraimer wrote:

Can it ask for a list of properrtyIds?
...

Given a list of propertyIds how does it obtain the information

associated with each id?

The V4 "client user interface" suggests these in the "DataAccess"

interface:

 	 list<string> getProperties()       Get a list of all the properties
 	 type_info getType(string property)
 	 string getAsString(string property)

Ca accepts a request to get data associated with a propertyId. Instead

of putting it into a caller provided container via the caller supplied

propertyCatalog, CA would make the data available via the caller

supplied dataViewer.

We pretend that the CA client library & data access doesn't hold the

data,

but only presents an interface for the user to copy the data into a
user-provided container.
Well, while you use dataAccess, the CA client library actually holds
the data in some temporary network buffer.
So you don't need a container at all if you only want to get a list
of all the properties & types.

 Does the proposed CA V4 interface allow this?

Yes, Jeff proposes a channel::createAllPropertiesReadRequest.
Does that cover your idea for a simply 'probe'- type application?

     createAllPropertiesReadRequest
     ...
     foreach p ( da->getProperties() )
     {
         display da->getType(p), da->getAsString(p)
     }

... or would you also like to see a request that only
gets the properties and types, without fetching any actual values?

-Kay

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System