Library paths and environment variables

Question

Hello,
I am using 10g AS 9.0.4 on a Unix system.
I am trying to convert an old JSP web application to work with 10g. It is not an EAR/WAR file so I am manually trying to set it up under the "default-web-app" folder. It uses a number of java class files which currently reside in $J2EE_HOME/default-web-app/WEB-INF/classes/mystuff.
These class files require access to a number of libraries. I foolishly believed that they would be accessible if I were to place them in the $J2EE_HOME/default-web-app/WEB-INF/lib folder, but that did not work.
I read that OC4J uses a "catch all" lib directory at $J2EE_HOME/applib. I copied the library files there and they still did not work.
Frustrated, I tried to print out the environment variables for the server - only to find that this function is not supported.
I managed to print out the library path by creating a Java class files which returns the following as a string:
System.getProperty("java.library.path");
This (when called from a JSP) prints a number of different library paths, none of which match those found listed in the $J2EE_HOME/config/application.xml file. I placed the library files in one of the paths listed by the "java.library.path" and it worked!
3 questions:
1. How do you print the server's environment variables using a JSP? This strikes me as a very useful function for sorting out library and path issues. Do a search on Google for "print environment variables OC4J" or something similar and there are no useful pages suggesting how this can be done.
2. Why are the default library paths different on the server than to those specified in application.xml?
3. How do I change the LD_LIBRARY_PATH (or any environment variable for that matter)? I have tried adding the following line to $ORACLE_HOME/Apache/Jserv/etc/jserv.properties without success:
wrapper.env=LD_LIBRARY_PATH=/my/custom/library/path
Any help you can offer would be most appreciated.

Answer 1

>
Thanks very much for a such a comprehensive response
- it has helped answer a lot of questions, especially
being able to print out the system properties. That
will be really useful!
No worries at all Rob.
The main hurdle is that the libraries are indeed
native (*.so) libraries. I hadn't considered that
until you pointed it out in your message. Can I
assume, then, that $J2EE_HOME/applib and
$J2EE_HOME/default-web-app/WEB-INF/lib are only
designed to handle Java's .JAR librares? That would
explain why placing the native libraries in there
didn't work, but is there a way of getting such
native libraries recognised and bundled up in a
WAR/EAR file?
Yep, that's it.
Our proprietary applib and the servlet specs web-inf/lib are only dealing with Java archives.
The J2EE specs don't cover how to deal with native libs like this.
Now I've NEVER EVER tried it, but it's worth a shot of at least trying -- for simplified packaging purposes, what you may be able to do is to distribute the .so's within the web-inf/lib -- and then just set that directory (where's its realized on the server after the app is deployed) to be referenced witihn the LD_LIBRARY_PATH. I'd expect our deployment manager will just ignore files it doesn't know about, so arguably you should be able to at least distribute them with the standard archive.
You'll need to specifically set the LD_LIBRARY_PATH as a separate task outside of the deployment operation though.
>
This is where things get a bit weird, and is partly
my fault during the installation of 10g AS.
We already had an existing installation of Oracle 10g
Database (10.1.0) at $ORACLE_HOME under the user
"oracle". I logged in as the user "oracle" to install
the Application Server into a different location (In
this case, "$ORACLE_HOME/../ias10g_9.0.4" - let's
call this $IAS_HOME). So there is no separate user
account for Oracle Database and Application Server
(and hence no separate $LD_LIBRARY_PATH).
If I log into UNIX as the user "oracle" and echo the
LD_LIBRARY_PATH, I get the following directories:
$ORACLE_HOME/lib
/usr/openv/netbackup/bin
/usr/dt/lib
/usr/lib
I use this user to do "opmnctl stopall" and "opmnctl
startall". If I then print out the library path from
a JSP using
"System.getProperty("java.library.path");", I get the
following paths:
$IAS_HOME/jdk/jre/lib/sparc/server
$IAS_HOME/jdk/jre/lib/sparc
$IAS_HOME/jdk/jre/../lib/sparc
$IAS_HOME/opmn/lib
$IAS_HOME/lib
$IAS_HOME/usr/lib
Which is totally different to those listed by
$LD_LIBRARY_PATH at the command line, which means
they must be coming from somewhere else.
It gets worse - my application is trying to call a
native library that is only present in the
$ORACLE_HOME/lib32 directory (libclntsh.so.10.1), so
unless I can include this path in the
"java.library.path" on the Applicaiton Server, then
my program will not work.
So, how do I change the "java.library.path" when the
values aren't coming from $LD_LIBRARY_PATH in the
first place?
The utility $IAS_HOME/opmn/bin/opmnctl is actually a shell script.
It has this section which sets the LD_LIBRARY_PATH:
if [ -z "$LD_LIBRARY_PATH" ]
then
LD_LIBRARY_PATH=$ORACLE_HOME/opmn/lib:$ORACLE_HOME/lib ; export LD_LIBRARY_PATH
else LD_LIBRARY_PATH=$ORACLE_HOME/opmn/lib:$ORACLE_HOME/lib:${LD_LIBRARY_PATH} ; export LD_LIBRARY_PATH
fi
So if you have an existing LD_LIBRARY_PATH env var set, it should just be putting its paths onto the front of it.
What you could try as a quick test is to edit the opmnctl script (after taking a backup of course) and either appending the path you need to it, or just add some debug statements to output the LD_LIBRARY_PATH value it ends up setting so you can try and work out what's causing it.
I expect these other entries:
$IAS_HOME/jdk/jre/lib/sparc/server
$IAS_HOME/jdk/jre/lib/sparc
$IAS_HOME/jdk/jre/../lib/sparc
are coming from the JRE when it is launched, in probably a similar manner to our opmn entries.
I really appreciate your help, and I bet if anyone
can answer these questions, you can! ;-)
You're very welcome.
cheers
-steve-