Simon,
unfortunately I am not too familar with the classloaders in Tomcat 3.2 and
3.3. If there are separate classloaders for each web app then you have the
same situation as with tomcat 4.0 (Catalina).
Regards Jochen
----- Original Message -----
From: "simon colston" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, September 17, 2001 12:39 PM
Subject: Re: Thanks for the note on JNI and class loading in the release
notes
> Jochen, Jonathon, Craig,
>
> Would the same thing be true for Tomcat 3.2 and 3.3??
>
> On Mon, 17 Sep 2001 10:06:18 +0200
> "Jochen Schneider" <[EMAIL PROTECTED]> wrote:
>
> JS> Hi Jonathan,
> JS>
> JS> we had the same problem and fixed it in the way described now in the
Tomcat
> JS> documentation.
> JS>
> JS> Probably one additional remark should be added to the documentation :
> JS>
> JS> If you place the Java code loading the native library outside of the
web
> JS> application (for example in $CATALINA_HOME/common/lib) it is loaded
only
> JS> once and the problem is solved.
> JS>
> JS> This sollution has some implication : The classes containing the
native code
> JS> are loaded by a classloader which has no knowledge about any class
which
> JS> resides in \Web-inf\lib. You will get an exception if you try to
instanciate
> JS> a class which resides in the \Web-inf\lib directory from your native
code!
> JS> You will also get an exception if you try to import a class which
resides in
> JS> the \Web-inf\lib\ directory from your java code in
$CATALINA_HOME/common/lib
> JS> since the two classes are loaded by different classloaders.
> JS>
> JS> This will not work (ClassA in $CATALINA_HOME/common/lib ansd ClassB in
> JS> \Web-inf\lib\ ) :
> JS>
> JS> ClassA :
> JS>
> JS> import ClassB;
> JS> public native static void doSomething(ClassB obj);
> JS>
> JS>
> JS> ClassB :
> JS>
> JS> import ClassA
> JS> public static void main(String[] args) {
> JS> ClassA.doSomething(this);
> JS> }
> JS>
> JS>
> JS> Now it works again :
> JS>
> JS> ClassA :
> JS>
> JS>
> JS> public native static void doSomething(Object obj);
> JS>
> JS>
> JS> ClassB :
> JS>
> JS> import ClassA
> JS> public static void main(String[] args) {
> JS> ClassA.doSomething((Object)this);
> JS> }
> JS>
> JS>
> JS> Is this description correct? How do you handle this problem? Is there
a more
> JS> elegant sollution ?
> JS>
> JS> Regards,
> JS> Jochen
> JS>
> JS>
> JS>
> JS>
> JS>
> JS> -------------------------------------
> JS> Tomcat 4.0 and JNI Based Applications:
> JS> -------------------------------------
> JS>
> JS> Applications that require native libraries must ensure that the
libraries
> JS> have
> JS> been loaded prior to use. Typically, this is done with a call like:
> JS>
> JS> static {
> JS> System.loadLibrary("path-to-library-file");
> JS> }
> JS>
> JS> in some class. However, the application must also ensure that the
library
> JS> is
> JS> not loaded more than once. If the above code were placed in a class
inside
> JS> the web application (i.e. under /WEB-INF/classes or /WEB-INF/lib), and
the
> JS> application were reloaded, the loadLibrary() call would be attempted a
> JS> second
> JS> time.
> JS>
> JS> To avoid this problem, place classes that load native libraries
outside of
> JS> the
> JS> web application, and ensure that the loadLibrary() call is executed
only
> JS> once
> JS> during the lifetime of a particular JVM.
> JS>
> JS>
> JS>
> JS> ----- Original Message -----
> JS> From: "Jonathan Eric Miller" <[EMAIL PROTECTED]>
> JS> To: "Tomcat Developer List" <[EMAIL PROTECTED]>
> JS> Sent: Saturday, September 15, 2001 5:59 AM
> JS> Subject: Thanks for the note on JNI and class loading in the release
notes
> JS>
> JS>
> JS> > I'm guessing that Craig is the one that added the section about JNI
and
> JS> > class loading in the RC1 release notes. I just wanted to say that I
> JS> > appreciate that you documented this.
> JS> >
> JS> > I also noticed that you fixed a problem that I noticed with the
Base64
> JS> > encoder where it had trailing zeroes.
> JS> >
> JS> > Thanks, Jon
> JS> >
> JS> >
> JS>
> JS>
> JS>
> JS>
> JS>
>
>
> --
> simon colston
> [EMAIL PROTECTED]
>
