Kodo Libraries on Mac OS X

Question

I'm evaluating Kodo on a Mac OS X system. I ran into a strange problem.
Kodo includes 13 libraries (.jar files). In Apple's Mac OS X Java
implementation, these kinds of third-party libraries are often placed in
the system-wide extensions directory /Library/Java/Extensions. For
example, that's where I've put my JDBC driver. When I tried this with
the Kodo libraries, however, the schematool stopped working - the class
loader couldn't find my application classes. The byte-code enhancer jdoc
worked fine and could find them, but not schematool.
For now I'm listing all 13 libaries in my CLASSPATH environment
variable, and that's working OK.
I'm curious - is this a known problem? Is there anything I can do to fix
it or work around it?
The two libraries causing the problem appear to be kodo-jdo-runtime.jar
and kodo-jdo.jar. If either or both of these files are placed in the
Extensions directory schematool stops working.
John Norstad
Academic Technologies
Northwestern University

Answer 1

John-
I finally tracked down this problem: libraries in the "installed
extensions" directory cannot load classes that are not also in that
directory (or in the bootstrap classloader). I guess this must be by
design, since you are seeing it on OSX and I can reproduce it on Linux
(Make A.jar that contains A.class, which just tries to load B.class. Put
A.jar in the extensions directory and B.class in your CLASSPATH, and try
to execute the main method of A.class: it will fail).
It is certainly a little wierd, though: it seems to limit the usefulness
of install extensions a bit.
John Norstad <[email protected]> wrote:
In article <[email protected]>,
Marc Prud'hommeaux <[email protected]> wrote:
Could you post the exact error message or stack trace that you are
seeing so we can look into it further?
Sure. I just repeated the following steps on my Mac OS X 10.1.4 system
to make sure I could reproduce the problem. This is all with Kodo 2.2.4
SP1 standard edition.
Step 1: I copied all 12 Kodo ".jar" files to /Library/Java/Extensions
(the same directory wich contains my JDBC driver). This is one of
several places where Java extensions can be located in Mac OS X.
Step 2: I set the CLASSPATH environment variable to the root of my
source code directory hierarchy.
Step 3: I changed my working directory to one of my package source code
directories. This directory also contains a "package.jdo" file for the
package.
Step 4: I compiled all my source code files:
javac *.java
This worked fine - javac managed to locate both the Kodo libraries and
my source code files.
Step 5: I ran the Kodo byte-code enhancer:
jdoc package.jdo
This also worked fine - jdoc properly enchanced all of my class files.
It was able to locate all of them with no trouble.
Step 5: I ran the schema tool:
% schematool -action refresh package.jdo
Exception in thread "main" java.lang.ClassNotFoundException:
my/big/long/package/path/MyClassName
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:297)
at java.lang.ClassLoader.loadClass(ClassLoader.java:253)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:313)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:120)
at
com.solarmetric.kodo.impl.jdbc.schema.SchemaTool.main(SchemaTool.java:111
5)
The tool was unable to locate the first class listed in package.jdo:
"MyClassName".
As I mentioned in the original article, I'm quite easily avoiding this
problem by simply enumerating all 12 Kodo ".jar" files in my CLASSPATH
environment variable and not trying to put them in that Mac OS X
extensions directory. Schematool has no problem with this. So I'm
getting plenty of work done and this is more a curiosity than a real
problem.
The big curiosity for me is why jdoc can find my classes but schematool
can't.
John Norstad
Academic Technologies
Northwestern University--
Marc Prud'hommeaux [email protected]
SolarMetric Inc. http://www.solarmetric.com
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