Experimental Physics and
Industrial Control System

"J. Lewis Muir" <[email protected]> · Thu, 04 Feb 2010 14:48:39 -0600

On 1/6/10 4:58 AM, Matej Sekoranja wrote:
> Hi, all!

Hi, Matej.

(Sorry to reply to this email so late.)

> 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.

I vote for the default to be to use the environment variables with a
switch to disable this behavior if one wants.  I ended up implementing
this behavior in my own software since it wasn't provided by CAJ, but it
would be nicer if CAJ provided it.

> 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.

I vote for option 1.  To me it's good to make CAJ behave just like the
C/C++ implementation (or to correctly implement the behavior according
to the CA reference manual).  If CAJ couldn't do this correctly before
Java 1.6, then it was deficient.  The moment Java *can* provide the
needed functionality, it would be good to take advantage of it in CAJ.
If someone needs to use an older version of Java, that's fine, they just
don't get the best behavior available now; they get the best behavior
available for that older version of Java.

Thanks,

Lewis

-- 
J. Lewis Muir
Software Engineer
IMCA-CAT

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System