NEXUS-5118: Initial imple

Goal is to make "bundle packaging" (which is basically Jetty + Nexus WAR)
use same LogBack instance (as we had problems reported by users in 2.0).

Changes:
* jetty.xml - umarked "server level" logback as hidden to make it really shared
* extracted custom appender into new module nexus-logging-extras-appender that is put top level
* nexus-logging-extras got component implementation for EventTarget
* logback-events.xml changed to use new appender
* bundle assembly changed that exclude all logging relevant JARs from Nexus WAR as they are _provided_ on top level from now on

This is WIP, not yet functional.

nexus/nexus-logging-extras-appender/pom.xml

@@ -0,0 +1,55 @@
+<!--
+
+    Sonatype Nexus (TM) Open Source Version
+    Copyright (c) 2007-2012 Sonatype, Inc.
+    All rights reserved. Includes the third-party code listed at http://links.sonatype.com/products/nexus/oss/attributions.
+
+    This program and the accompanying materials are made available under the terms of the Eclipse Public License Version 1.0,
+    which accompanies this distribution and is available at http://www.eclipse.org/legal/epl-v10.html.
+
+    Sonatype Nexus (TM) Professional Version is available from Sonatype, Inc. "Sonatype" and "Sonatype Nexus" are trademarks
+    of Sonatype, Inc. Apache Maven is a trademark of the Apache Software Foundation. M2eclipse is a trademark of the
+    Eclipse Foundation. All other trademarks are the property of their respective owners.
+
+-->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <groupId>org.sonatype.nexus</groupId>
+    <artifactId>nexus</artifactId>
+    <version>2.2-SNAPSHOT</version>
+  </parent>
+
+  <artifactId>nexus-logging-extras-appender</artifactId>
+  <name>Nexus : Logging Extras - Appender</name>
+
+  <dependencies>
+    <!-- We have components in here -->
+    <dependency>
+      <groupId>javax.inject</groupId>
+      <artifactId>javax.inject</artifactId>
+    </dependency>
+
+    <!-- Logging -->
+    <dependency>
+      <groupId>ch.qos.logback</groupId>
+      <artifactId>logback-core</artifactId>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>ch.qos.logback</groupId>
+      <artifactId>logback-classic</artifactId>
+      <scope>compile</scope>
+    </dependency>
+
+    <!-- Testing -->
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit-dep</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+</project>

nexus/nexus-logging-extras-appender/src/main/java/org/sonatype/nexus/logback/EventTarget.java

@@ -0,0 +1,26 @@
+/**
+ * Sonatype Nexus (TM) Open Source Version
+ * Copyright (c) 2007-2012 Sonatype, Inc.
+ * All rights reserved. Includes the third-party code listed at http://links.sonatype.com/products/nexus/oss/attributions.
+ *
+ * This program and the accompanying materials are made available under the terms of the Eclipse Public License Version 1.0,
+ * which accompanies this distribution and is available at http://www.eclipse.org/legal/epl-v10.html.
+ *
+ * Sonatype Nexus (TM) Professional Version is available from Sonatype, Inc. "Sonatype" and "Sonatype Nexus" are trademarks
+ * of Sonatype, Inc. Apache Maven is a trademark of the Apache Software Foundation. M2eclipse is a trademark of the
+ * Eclipse Foundation. All other trademarks are the property of their respective owners.
+ */
+package org.sonatype.nexus.logback;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+
+/**
+ * An target that receives logging events from {@link ForwardingAppender}.
+ * 
+ * @author cstamas
+ * @since 2.2
+ */
+public interface EventTarget
+{
+    void onEvent( ILoggingEvent event );
+}

nexus/nexus-logging-extras-appender/src/main/java/org/sonatype/nexus/logback/ForwardingAppender.java

@@ -0,0 +1,40 @@
+/**
+ * Sonatype Nexus (TM) Open Source Version
+ * Copyright (c) 2007-2012 Sonatype, Inc.
+ * All rights reserved. Includes the third-party code listed at http://links.sonatype.com/products/nexus/oss/attributions.
+ *
+ * This program and the accompanying materials are made available under the terms of the Eclipse Public License Version 1.0,
+ * which accompanies this distribution and is available at http://www.eclipse.org/legal/epl-v10.html.
+ *
+ * Sonatype Nexus (TM) Professional Version is available from Sonatype, Inc. "Sonatype" and "Sonatype Nexus" are trademarks
+ * of Sonatype, Inc. Apache Maven is a trademark of the Apache Software Foundation. M2eclipse is a trademark of the
+ * Eclipse Foundation. All other trademarks are the property of their respective owners.
+ */
+package org.sonatype.nexus.logback;
+
+import javax.inject.Inject;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+import ch.qos.logback.core.UnsynchronizedAppenderBase;
+
+/**
+ * A forwarding appender for Logback, that forwards {@link ILoggingEvent} events it gets as Appender, to it's target.
+ * 
+ * @author cstamas
+ * @since 2.2
+ */
+public class ForwardingAppender
+    extends UnsynchronizedAppenderBase<ILoggingEvent>
+{
+    @Inject
+    private EventTarget target;
+
+    @Override
+    protected void append( final ILoggingEvent event )
+    {
+        if ( target != null )
+        {
+            target.onEvent( event );
+        }
+    }
+}

nexus/nexus-logging-extras/pom.xml

@@ -26,6 +26,12 @@
   <name>Nexus : Logging Extras</name>
 
   <dependencies>
+    <!-- The appender -->
+    <dependency>
+      <groupId>org.sonatype.nexus</groupId>
+      <artifactId>nexus-logging-extras-appender</artifactId>
+    </dependency>
+
     <!-- We have components in here -->
     <dependency>
       <groupId>org.sonatype.sisu</groupId>

nexus/nexus-logging-extras/src/main/java/org/sonatype/nexus/log/internal/NexusEventSystemEventTarget.java

@@ -0,0 +1,49 @@
+/**
+ * Sonatype Nexus (TM) Open Source Version
+ * Copyright (c) 2007-2012 Sonatype, Inc.
+ * All rights reserved. Includes the third-party code listed at http://links.sonatype.com/products/nexus/oss/attributions.
+ *
+ * This program and the accompanying materials are made available under the terms of the Eclipse Public License Version 1.0,
+ * which accompanies this distribution and is available at http://www.eclipse.org/legal/epl-v10.html.
+ *
+ * Sonatype Nexus (TM) Professional Version is available from Sonatype, Inc. "Sonatype" and "Sonatype Nexus" are trademarks
+ * of Sonatype, Inc. Apache Maven is a trademark of the Apache Software Foundation. M2eclipse is a trademark of the
+ * Eclipse Foundation. All other trademarks are the property of their respective owners.
+ */
+package org.sonatype.nexus.log.internal;
+
+import javax.enterprise.inject.Typed;
+import javax.inject.Inject;
+import javax.inject.Named;
+import javax.inject.Singleton;
+
+import org.sonatype.nexus.logback.EventTarget;
+import org.sonatype.plexus.appevents.ApplicationEventMulticaster;
+
+import ch.qos.logback.classic.spi.ILoggingEvent;
+
+/**
+ * {@link EventTarget} that will multicast the incoming logging event to {@link ApplicationEventMulticaster}.
+ * 
+ * @author cstamas
+ * @since 2.2
+ */
+@Named
+@Singleton
+@Typed( EventTarget.class )
+public class NexusEventSystemEventTarget
+    implements EventTarget
+{
+    @Inject
+    private ApplicationEventMulticaster eventMulticaster;
+
+    @Override
+    public void onEvent( final ILoggingEvent eventObject )
+    {
+        if ( eventMulticaster != null )
+        {
+            final LogbackLoggingEvent logEvent = new LogbackLoggingEvent( eventObject );
+            eventMulticaster.notifyEventListeners( logEvent );
+        }
+    }
+}

nexus/nexus-logging-extras/src/main/resources/META-INF/log/logback-events.xml

@@ -19,7 +19,7 @@
 
 <included>
 
-  <appender name="events" class="org.sonatype.nexus.log.internal.NexusEventSystemAppender">
+  <appender name="events" class="org.sonatype.nexus.logback.ForwardingAppender">
     <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
       <level>WARN</level>
     </filter>

nexus/nexus-oss-webapp/pom.xml

@@ -65,6 +65,10 @@
       <groupId>ch.qos.logback</groupId>
       <artifactId>logback-classic</artifactId>
     </dependency>
+    <dependency>
+      <groupId>org.sonatype.nexus</groupId>
+      <artifactId>nexus-logging-extras-appender</artifactId>
+    </dependency>
 
     <!--  The Jetty itself -->
     <dependency>

nexus/nexus-oss-webapp/src/main/assembly/bundle.xml

@@ -91,6 +91,9 @@
         <excludes>
           <exclude>META-INF/**</exclude>
           <exclude>WEB-INF/lib/appcontext*.jar</exclude>
+          <exclude>WEB-INF/lib/slf4j-api*.jar</exclude>
+          <exclude>WEB-INF/lib/logback-core*.jar</exclude>
+          <exclude>WEB-INF/lib/logback-classic*.jar</exclude>
           <exclude>WEB-INF/classes/logback.xml</exclude>
         </excludes>
       </unpackOptions>
@@ -101,6 +104,7 @@
     <dependencySet>
       <includes>
         <include>org.sonatype.nexus:nexus-bootstrap</include>
+        <include>org.sonatype.nexus:nexus-logging-extras-appender</include>
         <include>javax.servlet:*</include>
         <include>org.eclipse.jetty:*</include>
         <include>org.codehaus.plexus:*</include>

nexus/nexus-oss-webapp/src/main/resources/content/conf/jetty.xml

@@ -51,12 +51,6 @@
       <Arg><Ref id="Contexts"/></Arg>
       <Arg>${nexus-webapp}</Arg>
       <Arg>${nexus-webapp-context-path}</Arg>
-      <Set name="serverClasses">
-        <Array type="java.lang.String">
-          <Item>org.slf4j.</Item>
-          <Item>ch.qos.logback.</Item>
-        </Array>
-      </Set>
       <Set name="extractWAR">false</Set>
       <Set name="throwUnavailableOnStartupException">true</Set>
     </New>

nexus/pom.xml

@@ -1111,6 +1111,11 @@
         <artifactId>nexus-logging-extras</artifactId>
         <version>${project.version}</version>
       </dependency>
+      <dependency>
+        <groupId>org.sonatype.nexus</groupId>
+        <artifactId>nexus-logging-extras-appender</artifactId>
+        <version>${project.version}</version>
+      </dependency>
       <dependency>
         <groupId>org.sonatype.nexus</groupId>
         <artifactId>nexus-api</artifactId>
@@ -1803,6 +1808,7 @@
     <module>nexus-utils</module>
     <module>nexus-web-utils</module>
     <module>nexus-logging-extras</module>
+    <module>nexus-logging-extras-appender</module>
     <module>nexus-api</module>
     <module>nexus-oss-edition</module>
     <module>nexus-configuration-model</module>