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<== Date ==> <== Thread ==>

Subject: Keck portable CA server usage
From: wlupton@keck.hawaii.edu (William Lupton)
To: tech-talk@aps.anl.gov
Cc: hill@luke.atdiv.lanl.gov
Date: Thu, 5 Nov 1998 17:12:56 -1000
Dear all,

This is in response to Jeff Hill's post of 29th October:
>This is a survey to determine who is currently using, or plans to use in
>the future, the new portable CA server library. If you are in this group
>please send a brief description of your current usage, your future
>plans, and your overall impression of the software so far.

We are using the portable CA server library for a Unix gateway to a
non-EPICS command processor (CP). The CA server uses static database
access to read .dbd and .db files (so it supports all the expected
recordtype-specific fields but not all the expected behavior). The CA
server caches the values of all the channels and so can service gets
without forwarding a request to the CP.  Puts are all handled
asynchronously at the CA server level; the asynchronous i/o completes on
receipt of a response from the CP.

We have plans to use a CA server as a gateway to isolate the real-time
systems (like the ANL gateway). This would not be identical to the ANL
gateway because we also intend that this gateway act as a simulator (it
would support switching between simulating locally and interacting with
the real-time systems). This effort has not yet begun.

We _still_ use the old (pre-C++) CA server library for our telescope
simulator. This works OK but has some restrictions. This will be
replaced by the new gateway-cum-simulator.

The software seems to be reliable and efficient. We had some crashing
problems (with large arrays) under Beta11 but we believe that these are
fixed in Beta12 (the problem was in GDD, not in the CA server library).
We do still have a problem with asynchronous i/o that completes after
the CA client has exited; we would be interested to hear other peoples'
experience of asynchronous i/o.

More documentation, especially theory of operation would be nice (but,
to be fair, we haven't looked at the LANL web-based documentation).

William Lupton

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