Re: CAJ usage

["J. Lewis Muir" <jlmuir@anl.gov>]

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" <jlmuir@anl.gov> 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 <kasemirk@ornl.gov> 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" <matej.sekoranja@gmail.com> 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>