Re: Personal impressions of EPICS meeting

[Tony Cox - (415)926-3105 <tcox@ssrl01.slac.stanford.edu>]

Harvey reports:-

>    Folks,

{snip}

>Jeff Hill - His priorities:
>              1. Finish portable ca server (promised by the end of this month).
>              2. Implement option of caching instead of queing ca server
>                 requests (done at request of CEBAF and easy to implement)
>              3. Support for larger arrays.  (Many of us beat on him to do
>                 this *soon*.)
>              4. Support for structures and user-defined data types will not
>                 be here until version 4.
>              5. Version 4 will also include option of setting priority for
>                 server requests.


If I remember, channel access V4 will also have support for elimination of
redundant byte-swapping between little-endian clients and servers.

I say 'If I remember', because although I think I keep bringing it up at
collaboration meetings (the last 3 at least), it never seems to make it into
the write-ups! Not that it is a burning issue right now - all current servers
are big-endian - but with proposed extensions to CA to support structures, 
arrays and various types of SDR's, unnecessary byte-swapping could turn into
quite a performance hit. I'm likely to want to use a (little-endian) alpha
SBC to package and transfer CCD images, and after all, 75% of all CPU's in the
world are little-endian too so it isn't that unreasonable...


(For those not too familiar with the background, under current CA protocols:-
	1) All data is transferred over the network in `big-endian' form.
	2) Little-endian clients (currently, only Alpha's) perform byte-swaps
as necessary to convert data to little-endian form.
	3) If we _did_ have any little-endian servers, they would be obliged to
byte-swap prior to sending out data, as they would have no way of finding out
that the receiver wasn't big-endian.)


Tony

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Dr Anthony D Cox
Computer Systems Specialist
Stanford Synchrotron Radiation Laboratory
Stanford Linear Accelerator Center
MS 69, Box 4349
Stanford CA 94305
tcox@ssrl01.slac.stanford.edu
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