Steve Lewis wrote:
At 7:44 AM -0500 2005/10/19, Marty Kraimer wrote:
Thus we can define
block - wait until all previous record processing activity has completed
process - request the linked record be processed
wait - do not complete this link until the linked record has completed
processing.
I like that; think of
block => a pre-condition
process => an attribute of the link
wait => a post-condition
Also, whatever scheme is chosen, it should map nicely into a visual
representation in VDCT.
Could we called the "linked to" record the "target" record?
I don't think viewing "block" as a precondition to link processing
captures enough of its capability, because it misses the code between
link invocations. This is most clear for input links:
read something (process target first; notify me on completion)
do some calculation using the data we will eventually have read
write something (block for outstanding callbacks before writing)
Block occurs too late to save the calculation from stale data, but
it would have been useful attached to the read link. If block is
implemented as a precondition, I would expect the following almost
immediately:
read something (process target first; notify me on completion)
--> link to nothing (block before not linking to anything)
do some calculation using the data we've now received
write something ...
I think attaching "block" to links is just expedient; it doesn't
fit perfectly, but putting it there gets a useful capability into
*all* record types.
I just wonder how an end user is going to specify that a link
should wait or block. Right now, I have a custom seq record that
allows the user to specify wait/nowait for each output link, but
of course this requires an extra field associated with each link.
--
Tim Mooney ([email protected]) (630)963-1860
Beamline Controls & Data Acquisition Group
Advanced Photon Source, Argonne National Lab.
- Replies:
- Re: Link arrays / syntax Andrew Johnson
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- [Fwd: Re: Link arrays / syntax] Marty Kraimer
- Re: [Fwd: Re: Link arrays / syntax] Benjamin Franksen
- Re: [Fwd: Re: Link arrays / syntax] Marty Kraimer
- Re: Link arrays / syntax Ralph Lange
- Re: Link arrays / syntax Marty Kraimer
- Re: Link arrays / syntax Steve Lewis
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