Experimental Physics and
Industrial Control System

"Chu, Paul" <[email protected]> · Wed, 6 Jan 2010 10:59:48 -0800

1) The reason why SLAC would like to use UNIX (or Linux) environment
variables for JCA (or CAJ in the future) is to be in synch with the
EPICS setup.  We got bitten once by out-of-synch between the environment
variables and the JCALibrary.properties.  Our environment variables are
maintained and updated better and those are supposed to be our "single
point of truth".  According to Kay Kasemir at SNS, they maintain the CSS
configuration file (or the Java side of the configuration) better than
the Linux environment variables.  They prefer to do the opposite -- Java
property/configuration being the truth source.

2) I also prefer your first solution for setting up the broadcasting
address in Java.  However, I think JCA/CAJ setup should be consistent
with the EPICS C/C++ side.  If one has an environment variable for that
purpose, JCA/CAJ should use that as well.

Thanks,
Paul

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Matej Sekoranja
Sent: Wednesday, January 06, 2010 2:59 AM
To: [email protected]
Subject: Re: CAJ or PV gateway problem?

Hi, all!

2 issues, 2 answers...

1) CAJ and JCA do not read environment variables

When CAJ was written reading env. variables was obsolete in Java (1.4).
Now is back.
I got a request from SLAC to implement reading env. variables for CAJ
and also for JCA.
It can be enabled with a special switch (for backward compatibility).
Default is not to use env. variables.
If you all agree, I can change the default.

2) CAJ is broadcasting to 255.255.255.255.

Prior Java 1.6 it was not possible to introspect all network interfaces.
So I was forced to use 255.255.255.255 as auto address.
Still I want CAJ to run on older Java version than 1.6. (Anyway, what do
you use?)
What to do (options)?
1) detect java version and if 1.6 use introspection to get broadcast
address of each network interfaces (might not be best solution since
behavior is not the same)
2) I got one proposal from APS to use special env. variable that
determines netmask; this would allow me to change 255.255.255.255 to
e.g. 192.168.0.255 (but still only one network IF!)
3) ... any suggestion from you :)

I guess I should go 1) and for older versions non-auto address list
should be used.

Cheers,
Matej

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System