Experimental Physics and Industrial Control System
When the CA client library runs inside the IOC it communicates with the
database service directly (w/o going through a socket). The client library
also communicates directly with the IOC's event queue. Considering that, and
considering that the new client interface and the new service interface will
be very close to identical then perhaps we can conclude that your vampire
can insert its fangs using the CA client library interface. Or in any case
we should probably invalidate that approach before defining a new interface.
Jeff
-----Original Message-----
From: Ralph Lange [mailto:[email protected]]
Sent: Wednesday, June 15, 2005 8:47 AM
To: EPICS Core Talk
Subject: V4 Database Access
Another thing that I recently found missing:
I think we agreed to introduce APIs between the IOC database and the CA
server that allow
- other (network) servers to register with the database (as listeners
being interested in getting events)
- other (database kind of) things to register as a new provider of
"records" (i.e. named DA property catalogs)
Where's the new thing (module, service, handler?) that provides these
interfaces?
Seen from 3.14, this takes over some of the functionality that has been
in the database and some from Channel Access.
It should handle record name resolution and connection to DA interfaces
(to handle requests coming in from servers).
It should also work as an event handler (broker?) that software modules
(like a server or the Vampire) can subscribe to and the database can
post its events to that get distributed to the registered listeners.
I'm not sure about the design as all this definitely sounds like a local
cut-down version of channel access. If we introduce client-specified
monitor deadbands - should handling these deadbands by client be moved
from CAS down into that layer to make it available for other
transports/servers?
I'm not trying to impose anything here ... it's just that the Vampire
needs to intercept db_post_event() and add more channels to the IOC
record namespace, and I don't know at which level that would be done.
Cheers,
Ralph
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