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[Internal] HTTP ERROR: 500 Unable to compile class for JSP

Zachary Norman

Attempting to run the IDL or ENVI Help under Windows may produce the following error message, regardless of the method used to initialize it:

HTTP ERROR: 500
Unable to compile class for JSP
RequestURI=/help/index.jsp

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Discussion
When launch the IDL or ENVI Help from a Windows platform the above error message appears in a browser o viewer window.

The IDL or ENVI Help when launched on a Windows platform will issue the above error message in a browser or viewer window.


Workaround

Newsgroups seem to suggest that the common cause of this error is that the Jetty HTTP Server cannot locate the java compiler.

The following are the modification to several .ini files that fixes the problem:

Part I

  1. cd to c:\program files\itt\idl71\idlde

  2. edit idlhelp.ini

  3. add these two lines, (assuming they installed in c:\program files\)

    -vm
    c:\program files\itt\idl71\idlde\jre\bin

This is just to make sure that idlhelp.exe is using the jre that we ship, which is 32 bit.

Part II

If the above modification does not work, it may be a file permission problem with regards to the .jsp files used by the help system. The .jsp files are copied during runtime.

Two files have to be modified to change the location where these files are copied.

1- The first file is:

c:\Program Files\ITT\IDL71\idlde\idlhelp.ini

We ship the file with the following lines:

-data
@user.home/.idl/itt/idlhelp

On most windows machines, @user.home maps to c:\Documents And Settings\. Replace all instances of @user.home with a that hard-coded location. For example, those two lines should look like:

-data
C:/Documents and Settings/<username&gt>

Also, a customer who reported they were using "Folder Redirection", could
try changing the line below the -data directive, to point to another location.

2- The second file to be modified is:

c:\Program Files\ITT\IDL71\idlde\configuration\config.ini

And replace all instances of @user.home with a hard-coded location (c:\Documents And Settings\<username&gt<>).

As an example, these two files will look like this after the modification:

1- idlhelp.ini

-nosplash
-application
com.rsi.idldt.helpApplication
-data
C:/Documents and Settings/<username&gt>-vmargs
-Dserver_host=127.0.0.1
-Dserver_port=51580</username&gt>


2- config.ini

#Product Runtime Configuration File

osgi.instance.area.default=C:/Documents and Settings/<username&gt>osgi.configuration.area=C:/Documents and Settings/<username&gt>osgi.splashPath=platform:/base/plugins/com.rsi.idldt
eclipse.product=com.rsi.idldt.workbench
osgi.bundles=org.eclipse.equinox.common@2:start,org.eclipse.update.configurator@3:
start,org.eclipse.core.runtime@start
osgi.bundles.defaultStartLevel=4</username&gt></username&gt>



NOTE: it is important to modify the config.ini file of the IDL distribution so that the fix works.

</username&gt<></username&gt>