Re: Knowing if a server application is running

[Matt Newville <newville@cars.uchicago.edu>]

Hi  Bo,

On Tue, Jan 17, 2017 at 9:35 AM, Bo Jakobsen <lister@f77.dk> wrote:

Hi all,

I am building an system based on EPICS and Matlab.
The idea of the system is that a "server" is running in Matlab. This server which monitors and manipulates EPICS records according to some logics.
This works very nicely and stable (even as I known that I should properly write it all as seq code, but that is out of the scope of my current project).

My problem is now that I would like to indicate to the user if the Matlab server is running or not through an EPICS record.

My thought was to periodically (e.g. at least ones per second) update a soft record from the Matlab server. But how can I from EPICS test if this has happened. It could e.g. be a time stamp, or a "running number".

Any input will be mostly appreciated

Bo

I do similar things regularly (though not in matlab), running a "server process" on a workstation that really needs to run and that other processes would communicate with via CA. I typically make a simple, small epics database, and include a "TimeStamp" or "HeartBeat" PV that (by convention) is written to only the server process to indicate that it running. I often have both a unix/epics epoch value that might be read by the client to detect a non-responsive server and a human-readable date that is displayed for the user. I think that's essentially what you are thinking, so I can say that this approach works well for me.

Sometimes a seq program is exactly the right thing, but sometimes a standalone server process is what you want.

--Matt