issues with tomcat and loading external libraries

protos

Hi,

I'm using redhat core 4 x86
tomcat 5.0

I'm new to tomcat and I'm trying to write a screenscraping prototype servlet
using the jakarta commons-httpclient.jar external library. I've based the
directory structure of the application on the demo given here :

http://tomcat.apache.org/tomcat-5.0-doc/appdev/processes.html

so it looks something like :

web
build
build.properties
build.xml
docs
src
      scraper
      first.java
web
      index.jsp
      WEB-INF
           lib
           web.xml

ant compiles the whole thing into the build directory. If the first.java file has
no references to external libraries the whole thing works fine.

The problems start when I try to get it to reference classes in the
commons-httpclient.jar. I'd prefer for this library to only be accessible to this
webapp, so I copied it into the web/WEB-INF/lib/ directory along with its
dependencies - some logging stuff and a decoding jar .......... - but ant does
not see the files in this location, and when I try to compile it using ant, will
spit out compiler messages relating to all lines of code referencing the
external lib.

My impression from research was that {app_root}/WEB-INF/lib was the
directory where external libs went ;
is there another step after copying the files there to register them with the
context classpath ?

Also - another thing, if I copy the external libraries to the system classpath at
/usr/share/tomcat5/common/lib/ The app will compile, but if I try and access
it through the browser it doesn't work and the tomcat logs give me this :

2006-10-27 14:56:49 StandardWrapperValve[jsp]: Servlet.service() for 
servlet jsp threw exception java.lang.NoClassDefFoundError: while resolving 
class: org.apache.commons.httpclient.URI
.
.
.
.
.
.
.
Caused by: java.lang.ClassNotFoundException: 
org.apache.commons.codec.DecoderException not found in 
gnu.gcj.runtime.SystemClassLoader{urls=[file:/usr/lib/jvm/java/lib/tools.jar,
file:/usr/share/tomcat5/bin/bootstrap.jar,
file:/usr/share/java/commons-logging-api.jar,
file:/usr/share/java/mx4j/mx4j.jar], 
parent= gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}

The decoder is a dependency of the httpclient and its jarfile is sitting right
beside the httpclient one.

Does anyone anyone have any ideas. Any help would be greatly appreciated.
I've been farting around with this trying to get it to work for far too long .....

Thanks

Colm

lynchie

You are correct in that all jar files e.g. commons-httpclient-xxx.jar etc should be in WEB-INF/lib. Tomcat should pick them up from there.

What is interesting is the stacktrace. Are you using the gnu java compiler and not Sun's? Try using plain sun compiler and jre. According to the stacktrace, the webapps/<your_app>/WEB-INF/lib folder is not on the classpath which is strange.

Civilian_Target

In your WEB-INF folder create a file called MANIFEST.MF and add the lines:

Manifest-Version: 1.0
Class-Path:  WEB-INF/lib/nameofjar.jar

I usually just put my JARs in the root directory so that I don't specify any path as an argument, just the name of the JAR. (But I also use Websphere instead of Tomcat. Go figure)

protos

thanks for the replies.

Yes - I'm using the gnu java compiler - I'll give the sun jdk a go and see if that makes a difference.

I have to say - the hardest thing with getting servlets / jsp working is not the actual programming but the configuration - its a real pain !!

Civilian_Target

protos wrote:

I have to say - the hardest thing with getting servlets / jsp working is not the actual programming but the configuration - its a real pain !!

If you're just starting out, I absolutely agree! The programming's familiar stuff but the configuration requires a good grasp of the concepts before you start, and most books don't explain these until later on.

[EDIT]If Tomcat is pissing you off - try WAS Community Edition - you might find it easier[/EDIT]