Re: CAJ questions

[Matej Sekoranja <matej.sekoranja@cosylab.com>]

Hi,

> > I have 2 questions about CAJ, the native Java Channel Access client
> > implementation.
> >
> > 1)  It seems like it behaves differently on computers with multiple
> > network interfaces from the C implementation.  On the C  
> > implementation
> > by default the broadcast address of each the networks is used when
> > searching for PVs.  On the CAJ implementation this does not seem to  
> > be
> > the case.  It is not finding PVs on one of these networks with the
> > default configuration, in my case on the 10.20.1.x subnet.  However,
> > if I set the following in my configuration file then it does work:
> >
> > gov.aps.jca.Context.auto_addr_list= false
> > gov.aps.jca.Context.addr_list= 10.20.1.255
> >
> > Is this an intended difference in behavior from the C implementation,
> > and if so is it documented?

Until Java 1.6, there was no (clean) way to "introspect" network  
interfaces to get broadcast address of all. Therefore, CAJ uses  
255.255.255.255 (auto) or be configured manually.
Java 1.6 supports this, but I do not want drop support for Java 1.5.
(Well, in fact I do a small "hack": compile code as 1.5 compatible,  
detect Java version and use appropriate code).

> > 2) My second question relates to knowing how to create configuration
> > lines such as those above in the JCALibrary.properties file.
> >
> > The documentation links in the CAJ User Manual here:
> > http://caj.cosylab.com/manual.html
> >
> > Include this one labelled "JCA tutorial on configuration":
> >
> > http://www.aps.anl.gov/bcda/jca/jca/2.1.2/tutorial.html
> >
> > But that tutorial only lists configuration lines like these:
> >
> > gov.aps.jca.jni.JNIContext.addr_list= toto.uses.this.ca.server
> > gov.aps.jca.jni.JNIContext.auto_addr_list= false
> >
> > These are for the JNI (e.g. C) implementation, not for the native  
> > Java
> > implementation.

See
http://jca.cosylab.com/apidocs/gov/aps/jca/JCALibrary.html#CHANNEL_ACCESS_JAVA

for native CAJ options.

However you can use "gov.aps.jca.Context." prefix to configure all CA  
java implementations, but note that specific configuration (prefix)  
overrides the general one.

> > There is another link on the CAJ User Manual Page which is labelled  
> > as
> > "CAJ configuration properties":
> > http://www.cosylab.com/jca/apidocs/gov/aps/jca/JCALibrary.html#CHANNEL_
> > ACCESS_JAVA

Link about is the right one now. Fixed. Thanks.

Cheers,
Matej