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<== Date ==> <== Thread ==>

Subject: Re: JCA problems and questions
From: Jack Smith <jacksmithvent2009@gmail.com>
To: "Chu, Paul" <chu@frib.msu.edu>
Cc: "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Date: Thu, 25 Oct 2012 09:16:31 -0400
Hi Paul and Kay,

Thanks for your excellent explanations. The combination of your guy's
explanations makes perfect.

When I open the webpage http://epics-jca.sourceforge.net/ , it says
"EPICS Java Channel Access implementation - JCA and JCA". See, "JCA
and JCA", confusing. Right?

It would be nice if the developers/maintainers could put your
explanations to the webpage to give a clear introduction to the
first-time user. The first impression always makes life-time memory:
bad or good.

Thanks,

J.S

On Wed, Oct 24, 2012 at 5:26 PM, Chu, Paul <chu@frib.msu.edu> wrote:
>
> Kay gave a very clear explanation.  So, in short:
>
> 1. JCA: Java Channel Access with JNI (C/C++) under the hood -- you will need the file libjca.so or an equivalent one
> 2. CAJ: pure Java implementation (trying to replicate what the JNI library) -- you will need caj.jar
>
> And, they both need jca.jar.
>
> Among experts, some people also call JCA/JNI for 1 and JCA/CAJ for 2.
>
> Paul
>
> > -----Original Message-----
> > From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-
> > bounces@aps.anl.gov] On Behalf Of Kasemir, Kay
> > Sent: Wednesday, October 24, 2012 5:01 PM
> > To: Jack Smith; Mark Rivers
> > Cc: tech-talk@aps.anl.gov
> > Subject: RE: JCA problems and questions
> >
> > Hi:
> >
> > I agree that it's confusing. Here's my understanding:
> >
> > JCA is the Java library for interacting with Channel Access.
> > It provides
> > 1) The API for creating a channel, handling the connection, adding a
> > subscription, receiving values, ...
> > 2) An actual implementation for the API, based on invoking the C/C++
> > Channel Access client library from EPICS 'base' via JNI, the Java native
> > interface.
> >
> > Any Java program that wants to interact with Channel Access needs part 1) of
> > JCA. It's a bit like the "include" file of a C/C++ program.
> > To actually work, you used to also need 2), which means: It's no longer pure
> > Java. You must have the JNI library of JCA that was compiled for your
> > operating system.
> >
> > CAJ replaces part 2) of JCA with a pure Java implementation that works for
> > everybody.
> >
> >
> > To me,
> > "JCA with JNI interface to Channel Access"
> > and
> > "JCA with CAJ"
> > are the two basic alternatives that you have.
> > Maybe there could be a better name for these.
> >
> > Thanks,
> > -Kay
> >
> >
> >
> > ________________________________________
> > From: tech-talk-bounces@aps.anl.gov [tech-talk-bounces@aps.anl.gov] On
> > Behalf Of Jack Smith [jacksmithvent2009@gmail.com]
> > Sent: Wednesday, October 24, 2012 4:18 PM
> > To: Mark Rivers
> > Cc: tech-talk@aps.anl.gov
> > Subject: Re: JCA problems and questions
> >
> > Hi,
> >
> > I always get confused and mess up the names of caj and jca. Could anyone
> > provide a simple explanation of what they stand for and what are their
> > differences so that jca/caj can be easily remembered, not easily messed up.
> > Can someone rename them? Thanks,
> >
>

References:
JCA problems and questions Mark Rivers
Re: JCA problems and questions Jack Smith
RE: JCA problems and questions Kasemir, Kay
RE: JCA problems and questions Chu, Paul

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