Attempting to call Java Servlet/Server App via PHP

Hello all:

Running into some difficulty here. I'm trying to call a java .jar file through PHP's "exec()" command-line execution process - Red Hat Linux environment. I'm successfully setting the working directory up front and the exec function returns no errors, but the java interpreter never actually gets fired off. Here's a sample code of what I'm trying to do:

<?php
$webdir = getcwd(); // Get main web root directory (should be "/var/www/html")
$sourcedir = "$webdir/java"; // We want to start in the java directory
chdir ($sourcedir); // Change to new java directory
$execparam = "java -jar JavaFile.jar &"; // Call the jar file and run in the background
exec ($execparam, $output, $return); // Run it
foreach ($output as $line) {
  print "$line<BR>";
}
print "$return<BR>";
?>

PHP:

That's it. Nothing is being stored in "$output" and "$return" returns "0", which I understand to be a successful run, yet no Java process gets started. I've also tried the "shell_exec()" and "system()" functions with similar (no) results.

Anything stand out to anyone on this? Any assistance appreciated.

 

Update:

When removing the "&" command to run this thing in the background, a generic error code of "127" is returned, rather than "0".

Additionally, when I tried using the "popen()" function, I need to specify the location of the java interpreter, but when I do, I get the following error which gives me a little more information: "sh: /usr/bin/java: Permission denied". I have since added the "apache" user to the "root" group, but that hasn't changed anything. Is this really a permissions problem or a path problem? Very confused now...

 

If the servlet is accessible online, why not calling it via an http request?

 

Because it has no interface. It's was strictly designed to be a command-line thing and it was decided to put a PHP front end on it later on. I've used command line executions before, but for some reason it's not behaving with Java. I ran into this situation on Windows, where I had to go into the actual Apache service preferences and click on the "Allow service to interact with desktop" checkbox, allowing PHP code to initiate a Windows client app. I get the feeling this is a similar issue, but in Linux, like there is some setting that will allow PHP to make remote command-line calls to Java.

 

This might help as well. Not a solution with the posters original code:

http://us3.php.net/manual/en/java.examples.php

 

Any other ideas?