Re: [EXTERNAL] Mimicking EVENT across IOCs

[Andrew Johnson via Tech-talk <tech-talk at aps.anl.gov>]

    Hi Andy,

On 7/25/22 9:49 AM, Hartman, Steven via Tech-talk wrote:

On Jul 24, 2022, at 6:42 PM, Wang, Andrew via Tech-talk <tech-talk at aps.anl.gov> wrote:

I am curious to know if anybody has found a good way to "replicate" event posting across IOCs. I am thinking about utilizing CPP flags, but not sure if that is a good solution.

If you can tolerate latency, each IOC can have its own event record. One IOC hosts a trigger record which can then use CA links to trigger processing of each of these event records (e.g. fanout, CP/CPP links, etc.). If you cannot tolerate the latency or need real-time performance, a hardware-based timing system is typical.

    Assuming you're looking for the slower network-based path you can
    avoid having to create extra records for forward-linking to each
    replica IOC by having the replica records process automatically
    using a CPP link as you originally asked. Something as simple as
    this may work, although I haven't actually tested it:
    
    record(event,
      "$(IOC)-local:event-$(EVENT)") {
        field(INP, "event-$(EVENT) CPP")
      }
    
    Note that the value of the EVENT macro doesn't have to match the
    actual event name/number, just the name of the record that it's
    replicating. It will get the event name/number from the VAL field of
    the originating record through the INP link. Using a CPP link like
    this would also be more efficient than forward-linking or fanouts if
    you have multiple IOCs that you're replicating the event to, since
    all the replicas get notified by the same CA monitor being posted,
    and the originating IOC doesn't need to know what other IOCs need to
    be notified either.
    
    - Andrew
-- 
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