I need to do some hacking to enable Logback Access logging for tomcat (http://forum.springsource.org/showthread.php?t=90535).

1) The built-in logback classes don't include logback-access as I found through experimentation, but I can't even find which built-in bundle contains any logback classes! I can find slf4j, but no logback. Is it hidden somewhere?!

2) One approach I am trying is to attach a fragment bundle to whatever bundle contains tomcat in order to provide the Logback Access bundle so I can configure a custom Tomcat <Valve> to use it. What bundle contains the relevant classes for parsing a custom <Valve> configuration entry in tomcat-server.xml?

I tried created a bundle with nothing in it but the manifest file below (to make a "bridge" between catalina and logback-access), but it didn't show up as an attached fragment in the bundle browser in the admin. I've not done a fragment before so maybe I'm doing something wrong, or else is there a restriction against adding a fragment to a built-in bundle?

Code:
Manifest-Version: 1.0
Bundle-ManifestVersion: 2
Bundle-Name: Tomcat Logback Access Bridge
Bundle-Version: 0.9.21
Bundle-Description: Fragment to add Logback-Access to DM Server Tomcat
Bundle-SymbolicName: tomcat.logback.access.bridge
Fragment-Host: com.springsource.org.apache.catalina.springsource
Import-Bundle: ch.qos.logback.access;version="[0.9.21,0.9.21]"
Export-Package: ch.qos.logback.access.net;uses:="ch.qos.logback.core.s
 pi,ch.qos.logback.access.spi,ch.qos.logback.core.helpers,ch.qos.logba
 ck.core.net,ch.qos.logback.access,ch.qos.logback.core,ch.qos.logback.
 core.boolex,ch.qos.logback.access.joran,ch.qos.logback.core.joran.spi
 ,ch.qos.logback.core.util";version="0.9.21",ch.qos.logback.access.jor
 an;uses:="ch.qos.logback.access.sift,ch.qos.logback.core.joran,ch.qos
 .logback.access.joran.action,ch.qos.logback.core,ch.qos.logback.acces
 s,ch.qos.logback.core.joran.action,ch.qos.logback.core.joran.spi";ver
 sion="0.9.21",ch.qos.logback.access.filter;uses:="ch.qos.logback.core
 .spi,ch.qos.logback.core.filter,javax.management,ch.qos.logback.core.
 util";version="0.9.21",ch.qos.logback.access.pattern;uses:="ch.qos.lo
 gback.core.status,ch.qos.logback.core.spi,ch.qos.logback.core.pattern
 ,ch.qos.logback.core,ch.qos.logback.access.spi,ch.qos.logback.core.ut
 il";version="0.9.21",ch.qos.logback.access.jetty.v7;uses:="org.eclips
 e.jetty.server,org.eclipse.jetty.http,ch.qos.logback.access.spi,ch.qo
 s.logback.core.spi,ch.qos.logback.core.status,ch.qos.logback.access.j
 oran,ch.qos.logback.core,org.eclipse.jetty.util.component,ch.qos.logb
 ack.core.joran.spi,ch.qos.logback.core.filter,ch.qos.logback.core.uti
 l,javax.servlet.http";version="0.9.21",ch.qos.logback.access.tomcat;u
 ses:="ch.qos.logback.core.spi,ch.qos.logback.core.status,ch.qos.logba
 ck.access.joran,org.apache.catalina.connector,org.apache.catalina.val
 ves,ch.qos.logback.core,ch.qos.logback.core.joran.spi,javax.servlet,c
 h.qos.logback.core.filter,ch.qos.logback.access.spi,org.apache.catali
 na,ch.qos.logback.core.util,javax.servlet.http";version="0.9.21",ch.q
 os.logback.access.html;uses:="ch.qos.logback.core.html,ch.qos.logback
 .core,ch.qos.logback.access.spi,ch.qos.logback.core.pattern,ch.qos.lo
 gback.access";version="0.9.21",ch.qos.logback.access.joran.action;use
 s:="ch.qos.logback.core,ch.qos.logback.core.joran.spi,ch.qos.logback.
 core.joran.action,ch.qos.logback.core.util,org.xml.sax,ch.qos.logback
 .access.boolex";version="0.9.21",ch.qos.logback.access.db;uses:="ch.q
 os.logback.access.spi,ch.qos.logback.core.db";version="0.9.21",ch.qos
 .logback.access;uses:="ch.qos.logback.access.pattern,ch.qos.logback.a
 ccess.spi,ch.qos.logback.core.pattern,ch.qos.logback.core,ch.qos.logb
 ack.core.status,javax.servlet,javax.servlet.http";version="0.9.21",ch
 .qos.logback.access.boolex;uses:="ch.qos.logback.access.spi,ch.qos.lo
 gback.core,ch.qos.logback.core.boolex";version="0.9.21",ch.qos.logbac
 k.access.spi;uses:="ch.qos.logback.core.spi,ch.qos.logback.core.filte
 r,ch.qos.logback.core,ch.qos.logback.access.servlet,javax.servlet.htt
 p";version="0.9.21",ch.qos.logback.access.sift;uses:="ch.qos.logback.
 core.spi,ch.qos.logback.access.spi,ch.qos.logback.core.sift,javax.ser
 vlet.http,ch.qos.logback.core.joran.event,ch.qos.logback.core.joran.s
 pi,ch.qos.logback.core.joran.action,org.xml.sax,ch.qos.logback.core";
 version="0.9.21",ch.qos.logback.access.servlet;uses:="javax.servlet,j
 avax.servlet.http";version="0.9.21",ch.qos.logback.access.jetty;uses:
 ="org.mortbay.jetty,ch.qos.logback.access.spi,ch.qos.logback.core.spi
 ,ch.qos.logback.core.status,ch.qos.logback.access.joran,ch.qos.logbac
 k.core,ch.qos.logback.core.joran.spi,ch.qos.logback.core.filter,ch.qo
 s.logback.core.util,javax.servlet.http";version="0.9.21"
Import-Package: ch.qos.logback.access;version="0.9",ch.qos.logback.acc
 ess.boolex;version="0.9",ch.qos.logback.access.db;version="0.9",ch.qo
 s.logback.access.filter;version="0.9",ch.qos.logback.access.html;vers
 ion="0.9",ch.qos.logback.access.jetty;version="0.9",ch.qos.logback.ac
 cess.jetty.v7;version="0.9",ch.qos.logback.access.joran;version="0.9"
 ,ch.qos.logback.access.joran.action;version="0.9",ch.qos.logback.acce
 ss.net;version="0.9",ch.qos.logback.access.pattern;version="0.9",ch.q
 os.logback.access.servlet;version="0.9",ch.qos.logback.access.sift;ve
 rsion="0.9",ch.qos.logback.access.spi;version="0.9",ch.qos.logback.ac
 cess.tomcat;version="0.9",ch.qos.logback.core;version="0.9",ch.qos.lo
 gback.core.boolex;version="0.9",ch.qos.logback.core.db;version="0.9",
 ch.qos.logback.core.filter;version="0.9",ch.qos.logback.core.helpers;
 version="0.9",ch.qos.logback.core.html;version="0.9",ch.qos.logback.c
 ore.joran;version="0.9",ch.qos.logback.core.joran.action;version="0.9
 ",ch.qos.logback.core.joran.event;version="0.9",ch.qos.logback.core.j
 oran.spi;version="0.9",ch.qos.logback.core.net;version="0.9",ch.qos.l
 ogback.core.pattern;version="0.9",ch.qos.logback.core.sift;version="0
 .9",ch.qos.logback.core.spi;version="0.9",ch.qos.logback.core.status;
 version="0.9",ch.qos.logback.core.util;version="0.9",javax.management
 ,javax.servlet,javax.servlet.http,org.apache.catalina,org.apache.cata
 lina.connector,org.apache.catalina.valves,org.eclipse.jetty.http;vers
 ion="7.0",org.eclipse.jetty.server;version="7.0",org.eclipse.jetty.ut
 il.component;version="7.0",org.mortbay.jetty,org.xml.sax
Note: logback-access-0.9.21.jar is a ready to go bundle when you donwload logback.