How do I use logback-access in combination with Tomcat 5.5?

Question

I've got several Web apps running on a Tomcat 5.5 server, and I'm working on improving/updating the overall logging system used throughout the system. I already had some success with logback-classic. However, when I try to use logback-access (i.e. access the lbAccessStatus servlet), I get this exception:

exception

javax.servlet.ServletException:
  Wrapper cannot find servlet class
    ch.qos.logback.access.ViewStatusMessagesServlet
  or a class it depends on

org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
...

root cause

java.lang.ClassNotFoundException:
  ch.qos.logback.access.ViewStatusMessagesServlet

org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1386)
...

I have everything set up according to the docs:

  common/lib:
    logback-classic-0.9.15.jar
    logback-core-0.9.15.jar
  server/lib:
    logback-access-0.9.15.jar

Moving around the libraries doesn't seem to help. logback-classic seems to work fine, it's just logback-access that causes problems.

Answer 1

I haven't used logback-access with tomcat, yet. I only used it with jetty...

I'd suggest to try the following setup, though:

common/lib:
  logback-access-0.9.15.jar
  logback-classic-0.9.15.jar
  logback-core-0.9.15.jar
server/lib:
  logback-access-0.9.15.jar
  logback-core-0.9.15.jar

logback-access has logback-core as a dependency. Since you use it both in the server (the Valve) and in your webapp (the ViewStatusMessagesServlet) you should add it to both classpaths.

You could (and should?) also add logback-access, logback-classic and logback-core to your webapp classpath instead of adding it to common/lib, making it available to all webapps.

Hope that helps.

Answer 2

If you put logback-access in common/lib too, so all the jars are there, it should be available everywhere. Have you tried that?

Also logging has been reworked in Tomcat 6. Is upgrading a possibility?

Answer 3

I've got it working. With maven and logback-classic the jars end in WEB-INF/lib and it works well. I've seen the same error only when deploying old version of my WAR.

excerpt of dependencies section of my pom.xml

<dependency>
  <groupId>org.slf4j</groupId>
  <artifactId>slf4j-api</artifactId>
  <version>${slf4j.version}</version>
</dependency>
<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>0.9.21</version>
</dependency>

... and relevant part of my web.xml:

  <servlet>
    <servlet-name>LogbackViewStatusMessages</servlet-name>
    <servlet-class>ch.qos.logback.classic.ViewStatusMessagesServlet</servlet-class>
  </servlet>
  <!-- see http://localhost:8080/oam-portal-portlets/logs -->
  <servlet-mapping>
    <servlet-name>LogbackViewStatusMessages</servlet-name>
    <url-pattern>/logback</url-pattern>
  </servlet-mapping>