extension functions and iPlanet was RE: extension functions and T omcat

[Uma Shinde <us...@openmarket.com>]

I did something similar for iplanet. I copied xalan.jar to the AppServer's
jre/lib/ext and the extension classes in WEB-INF location. I did get this
error
[07/Sep/2001 11:07:23:3] error: Exception: SERVLET-run_failed: Failed in
running
 template: /NASApp/cs/ContentServer, java.lang.NoClassDefFoundError:
javax/xml/p
arsers/FactoryConfigurationError
Exception Stack Trace:
java.lang.NoClassDefFoundError: javax/xml/parsers/FactoryConfigurationError

I had to copy xerces.jar also to the jre/lib/ext and then it works ok.

Am I on the right path here?

-Uma

-----Original Message-----
From: Gary L Peskin [mailto:garyp@firstech.com]
Sent: Monday, August 13, 2001 4:33 PM
To: xalan-dev@xml.apache.org
Subject: Re: extension functions and Tomcat


Hi, Dmitry --

Can you please try this to help us out?

1.  Be sure you have the following:

<RequestInterceptor
             className="org.apache.tomcat.request.Jdk12Interceptor" />

as the LAST RequestInterceptor in your conf/server.xml file.

2.  Place xalan.jar ONLY in ${tomcat_lib}/lib

3.  Place your extension ONLY in ${web_app}/web-info/lib

4.  Stop/Start Tomcat

5.  Tell us if this is able to find your extension now.

Thanks,
Gary


Dmitry Beransky wrote:
> 
> Gulli,
> 
> I will disagree on a couple of accounts, if I may,
> 
> First, how a class loader finds classes is completely up to the particular
> classloader.  For example, it is my understanding that in Tomcat 3.2 and
> prior, the classloader would do a postfix traversal of the loader
> hierarchy, that is, it would first delegate loading to the parent loader
> and if the parent couldn't locate the class, then it would apply its own
> heuristics, whatever they are.  In Tomcat 3.3 & 4.0, this behavior has
been
> changed to prefix traversal.
> 
> It "should" be possible to place xalan.jar in ${tomcat_home}/lib and have
> it shared by all the applications, but apparently, currently it doesn't
> work.  Hence, my problem.  That's because when xalan is in tomcat's lib
> directory, it's been loaded by Tomcat's classloader (not the application
> loader) and it actually always stays withing the context of that
> classloader (that's why I believe that getContextClassLoader() call
doesn't
> really do anything useful).
> 
> Regards
> Dmitry
> 
> At 12:26 PM 8/13/2001, Gunnlaugur Thor Briem wrote:
> >Hi,
> >
> >just to clear it up for everyone, the fix makes perfect sense,
> >but no, it isn't necessary to copy xalan.jar into every webapp.
> >
> >It makes sense because you made sure that xalan.jar was found by
> >the same classloader as your extension classes. That is the real
> >requirement. You satisfied this requirement by placing xalan.jar
> >in the webapp classloader, where the extension classes were. If
> >the same xalan.jar needs to be available to ALL webapps in the
> >servlet engine (which it probably usually does) then you should
> >instead satisfy this requirement by placing the extension classes
> >in the ${tomcat_home}/lib, where xalan.jar was originally. Either
> >way will work -- they just need to be together.
> >
> >Actually, to be pedantically precise, having xalan.jar in the
> >webapp lib and the extension classes in ${tomcat_home}/lib would
> >also work (though it would be a pretty silly configuration)...
> >the extension classes need to be accessible to Xalan's classloader,
> >and they are, if they are defined in that classloader or one of its
> >ancestor classloaders. The ${tomcat_home}/lib classloader is the
> >parent or ancestor classloader of any webapp classloader, hence
> >any class defined in it is available in any webapp.
> >
> >This is all crystal-clear if you know how a ClassLoader finds its
> >classes. When asked to find a class, any ClassLoader will first
> >ask its parent classloader and then try to to find the class
> >itself, but will not ask any of its child classloaders (I believe
> >it doesn't even know about them). For the complete story, see
> >http://java.sun.com/j2se/1.3/docs/api/java/lang/ClassLoader.html
> >
> >Hope that leaves no trace of confusion! :)
> >
> >         - Gulli
> >