Re: PV name changes and epics extensions

[Don Dohan <dohan@aps.anl.gov>]

Emmanuel

This is one of the features of the IRMIS relational database. 

IRMIS consists of, in part, all of the PVs in your system.  A pv crawler 
(a perl program) detects when an IOC reboots, then scans and expands 
that IOC's st.cmd file to load the IRMIS database with that IOCs PVs.  
This scanning is unobtrusive to the IOC.

Other crawlers have been written to scan CA clients.  At the APS, we 
crawl for MEDM, ALH, and SDDS clients, and we are testing the SNL 
crawler written at SLAC.  We intend to crawl save/restore files as well 
(future).  For each CA client instance, a list of resolved PVs is 
generated, and inserted into the IRMIS database.

Taking the MEDM client as an example, the crawler resolves the macro 
substitutions for nested MEDM screens, so that it tells you which .adl 
file in the chain needs to be fixed if a given PV is removed.

Crawlers for other CA clients have been written at other facilities - 
EDM, DM/2K for example.

Don Dohan

Emmanuel Mayssat wrote:
> Another question about software upgrade...
>
> Let's say that I change the name of PV in my epics database.
> Potentially with this change, I could break epics extensions.
> Medm of course, but also feedback system, PV backup, etc.
>
> Is there a way to know which extensions will break if I change a PV
> name? (may keeping track for each extension of the used PVs in a flat
> file is the solution, but is there any other, smarter ones?)
>
> --
> Emmanuel
>
>