Re: More radical ideas

[Benjamin F. <ben...@he...>]

Am Dienstag, 27. November 2012, 20:24:29 schrieb Benjamin Franksen:
> Where does that lead us? If we follow this course consequently, we arrive
> at a 'dualized' version of EPICS (maybe I should call it Co-EPICS, ha,
> ha): in this model records are (almost) 'dumb' stores of data (no link
> fields, no processing, just get and put but also monitor, so not
> /completely/ dumb), while all the intelligence (processing) is in what
> connects them, i.e. in the links. Links never store any data inside them,
> they contain /only/ link fields. Record types would all have the same
> generic support, and differ only in the data layout. On the other hand,
> we'd have a larger variety of link types, perhaps (roughly) corresponding
> to what Marty has in javaIOC for structure support.

Sorry this was less than clear. In EPICS a link /is/ a link field. Here is the
same idea, expressed in less confusing terminology. There'd be two sorts of
records:

 * "Process variable records" handle the putField/getField/monitor
   functionality. These are the access points for code external to the
   database, e.g. through CA or pvAccess. They contain no link fields and have
   generic "support" (which means there is only one generic implementation of
   their interface).

 * "Action records" handle device (and other) I/O, do calculations, process
   other records in sequence or parallel, etc. These contain /only/ link fields
   and no data. They have non-generic, specialised "support" (implementations
   of process, initialize, etc). Since they have no data fields, they cannot be
   "seen" from outside the database (or at least not the interesting part,
   which is the process() code).

Another way to view this model is to compare it to programming idioms: while
the current model is object-oriented, this one is procedural.

As I said, I am not yet convinced this is a good idea; at least it can serve
as an interesting point in the design space.

Cheers
--
Ben Franksen
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