Experimental Physics and
Industrial Control System

"J. Lewis Muir" <[email protected]> · Wed, 09 May 2007 09:32:47 -0400

J. Lewis Muir wrote:

David Dudley wrote:

Ok, getting much closer now.
I switched from blackdown-jdk-1.4.2.03 to sun-jdk-1.5.0.11.  Things are
starting to work better now.
Made the modifications suggested to the build.xml file to remove the
jni interface.  I don't think I can manage any native interface code in
this particular application given the varied machine architectures that
are going to access it.
jca now compiles without error.   After adding the reference to the jca
library in caj, it compiles fine also.
Modified my classpath to include the output .jar files, and now I can
compile the 'SimpleJCAGet.java' program without errors.
I have a data point named 'TotalSystemLoad' which is the total KW used
by the plant, and I can do a camonitor 'TotalSystemLoad' on that
successfully.
However, when I say 'java SimpleJCAGet TotalSystemLoad', I get:
'Exception in thread "main" java.lang.NoClassDefFoundError:
SimpleJCAGet'.
Getting better, I just need to get some decent java training, I guess.
David

It looks like it can't find SimpleJCAGet. SimpleJCAGet needs to be on
your classpath too. Where is SimpleJCAGet.class? What package is
SimpleJCAGet in (i.e. the package declaration at the top of
SimpleJCAGet.java, or the default package if there is no such declaration)?
If SimpleJCAGet is in the default package, then your classpath should
include the directory where SimpleJCAGet.class resides. If SimpleJCAGet
is in a package, say "com.cctexas", then your classpath should include
the directory that contains the com directory (where the
SimpleJCAGet.class file is at com/cctexas/SimpleJCAGet.class).
-lewis

Hi, David.
I should have also noted that in the case where SimpleJCAGet is in a
package, you will need to refer to it by its fully qualified name when
running it from the command line. For example:
$ java com.cctexas.SimpleJCAGet TotalSystemLoad
-lewis
"J. Lewis Muir" <[email protected]> 5/8/2007 3:14 PM >>>

David Dudley wrote:

Well, getting closer.
I had jca-2.3.1 source downloaded earlier.
Moved to directory and did 'ant', it said:
build.core.java:
     [echo] Building core classes
    [javac] Compiling 67 source files to
/usr/local/EPICS/modules/soft/jca/jca-2.3.1/O.core
    [javac]
/usr/local/EPICS/modules/soft/jca/jca-2.3.1/src/core/gov/aps/jca/dbr/DBR_Double.java:89: 
cannot resolve symbol

[javac] symbol : method format

(java.util.Locale,java.lang.String,java.lang.Object[])

[javac] location: class java.lang.String

[javac] toValue[i] =

String.format(Locale.US, formatFString, params);

[javac]

^
    [javac]
/usr/local/EPICS/modules/soft/jca/jca-2.3.1/src/core/gov/aps/jca/dbr/DBR_Double.java:93: 
cannot resolve symbol

[javac] symbol : method format

(java.util.Locale,java.lang.String,java.lang.Object[])

[javac] location: class java.lang.String

[javac] toValue[i] =

String.format(Locale.US, formatEString, params);

[javac]

       ^
    [javac]
/usr/local/EPICS/modules/soft/jca/jca-2.3.1/src/core/gov/aps/jca/dbr/DBR_Float.java:91: 
cannot resolve symbol

[javac] symbol : method format

(java.util.Locale,java.lang.String,java.lang.Object[])

[javac] location: class java.lang.String

[javac] toValue[i] =

String.format(Locale.US, formatFString, params);

[javac]

^
    [javac]
/usr/local/EPICS/modules/soft/jca/jca-2.3.1/src/core/gov/aps/jca/dbr/DBR_Float.java:95: 
cannot resolve symbol

[javac] symbol : method format

(java.util.Locale,java.lang.String,java.lang.Object[])

[javac] location: class java.lang.String

[javac] toValue[i] =

String.format(Locale.US, formatEString, params);

[javac]

       ^
    [javac]
/usr/local/EPICS/modules/soft/jca/jca-2.3.1/src/core/gov/aps/jca/jni/JNIContext.java:147: 
cannot resolve symbol
    [javac] symbol  : constructor IllegalStateException
(java.lang.String,java.lang.Throwable)
    [javac] location: class java.lang.IllegalStateException
    [javac]       throw new IllegalStateException( "Context not
initialized", th );
    [javac]             ^
    [javac] 5 errors
BUILD FAILED
/usr/local/EPICS/modules/soft/jca/jca-2.3.1/build.xml:144: Compile
failed; see the compiler error output for details.
Total time: 5 seconds
Getting closer, I would say.
So, you're saying that caj only replaces the JNI part of jca with a
java package, instead of the native interface package?

That's correct. Instead of using the EPICS libraries for Channel Access
communication, CAJ implements the Channel Access protocol in Java.
About your build problem. What archive of JCA did you download? When I
downloaded the tar-gz file from http://jca.cosylab.com/ and extracted
it, tar said "tar: A lone zero block at 1809". I downloaded the zip

file and it extracted cleanly:
$ curl -O http://jca.cosylab.com/distributions/jca-2.3.1-src.zip
Before building JCA, I set EPICS_BASE_RELEASE (sh shell):
$ export EPICS_BASE_RELEASE=/opt/epics-3.14.8.2/base
If you're planning to use the ant install target, you should set
EPICS_EXTENSIONS to an appropriate value also.
Then I was able to do
$ ant clean
$ ant
If you are planning to use only the CAJ Channel Access implementation,
you could consider compiling JCA without the native EPICS libraries.
However, I don't know that this is officially supported. I was able to
successfully compile JCA without native EPICS libraries by removing the
build.core.jni target from the depends attribute of the build.core
target in build.xml:
---replace this---
<target name="build.core" depends="build.core.java,build.core.jni">
---with this (i.e. remove "build.core.jni" target dependency)---
<target name="build.core" depends="build.core.java">
---
In this case, I just did (sh shell)
$ export EPICS_BASE_RELEASE=''
$ ant clean
$ ant
The JAR file is created at "O.core/jca.jar".
-lewis
Kay-Uwe Kasemir <[email protected]> 5/8/2007 2:24 PM >>>

Hi:
You need jca, which gives you
a) The basic java API, a lot of interfaces, in a jca.jar file.
    That's what ant complains about with the missing gov.aps.jca.
b) A JNI implementation of those interfaces,
    using the CA client lib from EPICS base,
    in some *so or *dll file.
Just jca works fine, but the problem is that it depends on the
JNI implementation, i.e. binary, system-dependent code.
You need to build the JNI part of jca for Win32, Linux, Linux

64-bit,

OSX-on-ppc, OSX-on-intel, for every version of EPICS base that
you want to use.
CAJ provides a pure java implementation, so it replaces (b).
At the SNS, we had some problems with CAJ possibly causing
hangups of CA server threads on IOCs, but the current hope is
that that's been fixed as long as you use the latest jca/caj
and IOCs run R3.14.9.
-Kay

On May 8, 2007, at 15:04 , David Dudley wrote:
I'm trying to configure and use the CAJ library, since I can't be

sure

what kind of machine the application will be used on. It can
almost be

guaranteed that whatever machine it is, it won't have EPICS on it,

for

sure.
I downloaded caj-1.1.3-src and caj-1.1.3.tar, and am attempting to
figure out how to use it.
From the caj-1.1.3 source directory, I can't get ant to operate
without

giving pages and pages of errors. It looks for package

'gov.aps.jca',

but shows that package does not exist.
Still working on getting use to java, I've been a 'c' programmer

for

around 20 years or so.
All I did was go go to the source directory and type 'ant'.  Was

there

something else I was supposed to do as well?
David
"Matej Sekoranja" <[email protected]> 11/26/2006 1:49 PM
Hi,
sorry for the late reply.
Is there any additional information on utilizing the Jca library

other

than the Tutorial listed? I'd like to use a 'monitor' function to

display

changing data, but there isn't exactly any documentation on it.

There is a series of EPICS training material.

Java and JCA can be found here:

http://www.aps.anl.gov/aod/bcda/epicsgettingstarted/developtools/
java.html
See also CA client library tutorials.
Any help would be appreciated.

The best thing is to look at BasicExample source (found in the
sources). I
attach it anyway.
Matej
<David Dudley.vcf>

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System