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

Subject: Re: Channel access and ca_element_count
From: Benjamin Franksen <benjamin.franksen@bessy.de>
To: tech-talk@aps.anl.gov
Date: Mon, 5 Oct 2009 22:54:33 +0200
On Montag, 5. Oktober 2009, Andrew Johnson wrote:
> On Monday 05 October 2009 10:24:25 Jeff Hill wrote:
> > In the short term:
> > Clients _are_ currently allowed to _not_ specify the element count when
> > they subscribe (they can specify an element count of zero). So perhaps
> > the CA code should be changed allowing the array length to be dynamic
> > in just that situation. Currently, we are locking the element count for
> > that situation to what was there when the channel connects, but perhaps
> > this is wrong (lazy) etc. Any opinions from Andrew or others?
>
> I agree with Michael in favor of changing the behavior so that when a
> client specifies COUNT=0 in its subscription, it is requesting a dynamic
> element count such that successive events may have different numbers of
> elements. However it should never be given more than ca_element_count()
> elements so it can always use that number to allocate data storage at
> connection time.  If at some time in the future we want to make it
> possible for even that number to be increased, this could be indicated to
> the client by a pair of disconnect/ reconnect events.

I would be very happy if something like this could be done at the database 
level i.e. for pv links between records.

Cheers
Ben



Replies:
Re: Channel access and ca_element_count Andrew Johnson
References:
Channel access and ca_element_count michael.abbott
RE: Channel access and ca_element_count Jeff Hill
Re: Channel access and ca_element_count Andrew Johnson

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