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

Subject: applications that use channel access
From: hill@luke.atdiv.lanl.gov (Jeff Hill)
Date: Mon, 9 May 94 16:34:08 MDT

Hello all,

This message is directed to the authors or maintainers of application
software that uses the channel access client library.

>From the channel access client library callable interface it is possible
to specify that a connection is to be made to a named channel and
to __simultaneously__ fetch the value of the channel. It is the perception 
of the author that this is a very rarely used feature of channel access.

Based on no negative feedback from a previous message I have
decided to eliminate this feature of channel access from future 
releases of EPICS beginning with release 3.12. I will preserve 
existing functionality however I will preclude performing both operations
from the same request. After the change applications will be forced
to wait for a channel to connect prior to fetching its value.
 
Your application is using this feature of channel access if __all__ of 
the following are true.

o your application calls one of ca_build_and connect(),
	ca_array_build(), or ca_build_channel()
o your application specifies an external type other than TYPENOTCONN 
	to one of the calls above
o your application supplies a non-zero pointer specifying a location 
	where the channel's value is to be written to one of the calls above.
o your application specifies an array element count other than zero to
	one of the calls above.


Jeff

______________________________________________________________________
Jeffrey O. Hill			Internet	hill@atdiv.lanl.gov
LANL MS H820			Voice		505 665 1831
Los Alamos, NM USA 87545	FAX		505 665 5107


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