diff --git a/library/log4php/LoggerAppender.php b/library/log4php/LoggerAppender.php
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+++ b/library/log4php/LoggerAppender.php
@@ -0,0 +1,289 @@
+<?php
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * @package log4php
+ */
+
+/**
+ * Abstract class that defines output logs strategies.
+ *
+ * @version $Revision: 1374777 $
+ * @package log4php
+ */
+abstract class LoggerAppender extends LoggerConfigurable {
+
+    /**
+     * Set to true when the appender is closed. A closed appender will not
+     * accept any logging requests.
+     * @var boolean
+     */
+    protected $closed = false;
+
+    /**
+     * The first filter in the filter chain.
+     * @var LoggerFilter
+     */
+    protected $filter;
+
+    /**
+     * The appender's layout. Can be null if the appender does not use
+     * a layout.
+     * @var LoggerLayout
+     */
+    protected $layout;
+
+    /**
+     * Appender name. Used by other components to identify this appender.
+     * @var string
+     */
+    protected $name;
+
+    /**
+     * Appender threshold level. Events whose level is below the threshold
+     * will not be logged.
+     * @var LoggerLevel
+     */
+    protected $threshold;
+
+    /**
+     * Set to true if the appender requires a layout.
+     *
+     * True by default, appenders which do not use a layout should override
+     * this property to false.
+     *
+     * @var boolean
+     */
+    protected $requiresLayout = true;
+
+    /**
+     * Default constructor.
+     * @param string $name Appender name
+     */
+    public function __construct($name = '') {
+        $this->name = $name;
+
+        if ($this->requiresLayout) {
+            $this->layout = $this->getDefaultLayout();
+        }
+    }
+
+    public function __destruct() {
+        $this->close();
+    }
+
+    /**
+     * Returns the default layout for this appender. Can be overriden by
+     * derived appenders.
+     *
+     * @return LoggerLayout
+     */
+    public function getDefaultLayout() {
+        return new LoggerLayoutSimple();
+    }
+
+    /**
+     * Adds a filter to the end of the filter chain.
+     * @param LoggerFilter $filter add a new LoggerFilter
+     */
+    public function addFilter($filter) {
+        if ($this->filter === null) {
+            $this->filter = $filter;
+        } else {
+            $this->filter->addNext($filter);
+        }
+    }
+
+    /**
+     * Clears the filter chain by removing all the filters in it.
+     */
+    public function clearFilters() {
+        $this->filter = null;
+    }
+
+    /**
+     * Returns the first filter in the filter chain.
+     * The return value may be <i>null</i> if no is filter is set.
+     * @return LoggerFilter
+     */
+    public function getFilter() {
+        return $this->filter;
+    }
+
+    /**
+     * Returns the first filter in the filter chain.
+     * The return value may be <i>null</i> if no is filter is set.
+     * @return LoggerFilter
+     */
+    public function getFirstFilter() {
+        return $this->filter;
+    }
+
+    /**
+     * Performs threshold checks and invokes filters before delegating logging
+     * to the subclass' specific <i>append()</i> method.
+     * @see LoggerAppender::append()
+     * @param LoggerLoggingEvent $event
+     */
+    public function doAppend(LoggerLoggingEvent $event) {
+        if ($this->closed) {
+            return;
+        }
+
+        if (!$this->isAsSevereAsThreshold($event->getLevel())) {
+            return;
+        }
+
+        $filter = $this->getFirstFilter();
+        while ($filter !== null) {
+            switch ($filter->decide($event)) {
+                case LoggerFilter::DENY:
+                    return;
+                case LoggerFilter::ACCEPT:
+                    return $this->append($event);
+                case LoggerFilter::NEUTRAL:
+                    $filter = $filter->getNext();
+            }
+        }
+        $this->append($event);
+    }
+
+    /**
+     * Sets the appender layout.
+     * @param LoggerLayout $layout
+     */
+    public function setLayout($layout) {
+        if ($this->requiresLayout()) {
+            $this->layout = $layout;
+        }
+    }
+
+    /**
+     * Returns the appender layout.
+     * @return LoggerLayout
+     */
+    public function getLayout() {
+        return $this->layout;
+    }
+
+    /**
+     * Configurators call this method to determine if the appender
+     * requires a layout.
+     *
+     * <p>If this method returns <i>true</i>, meaning that layout is required,
+     * then the configurator will configure a layout using the configuration
+     * information at its disposal.     If this method returns <i>false</i>,
+     * meaning that a layout is not required, then layout configuration will be
+     * skipped even if there is available layout configuration
+     * information at the disposal of the configurator.</p>
+     *
+     * <p>In the rather exceptional case, where the appender
+     * implementation admits a layout but can also work without it, then
+     * the appender should return <i>true</i>.</p>
+     *
+     * @return boolean
+     */
+    public function requiresLayout() {
+        return $this->requiresLayout;
+    }
+
+    /**
+     * Retruns the appender name.
+     * @return string
+     */
+    public function getName() {
+        return $this->name;
+    }
+
+    /**
+     * Sets the appender name.
+     * @param string $name
+     */
+    public function setName($name) {
+        $this->name = $name;
+    }
+
+    /**
+     * Returns the appender's threshold level.
+     * @return LoggerLevel
+     */
+    public function getThreshold() {
+        return $this->threshold;
+    }
+
+    /**
+     * Sets the appender threshold.
+     *
+     * @param LoggerLevel|string $threshold Either a {@link LoggerLevel}
+     *   object or a string equivalent.
+     * @see LoggerOptionConverter::toLevel()
+     */
+    public function setThreshold($threshold) {
+        $this->setLevel('threshold', $threshold);
+    }
+
+    /**
+     * Checks whether the message level is below the appender's threshold.
+     *
+     * If there is no threshold set, then the return value is always <i>true</i>.
+     *
+     * @param LoggerLevel $level
+     * @return boolean Returns true if level is greater or equal than
+     *   threshold, or if the threshold is not set. Otherwise returns false.
+     */
+    public function isAsSevereAsThreshold($level) {
+        if ($this->threshold === null) {
+            return true;
+        }
+        return $level->isGreaterOrEqual($this->getThreshold());
+    }
+
+    /**
+     * Prepares the appender for logging.
+     *
+     * Derived appenders should override this method if option structure
+     * requires it.
+     */
+    public function activateOptions() {
+        $this->closed = false;
+    }
+
+    /**
+     * Forwards the logging event to the destination.
+     *
+     * Derived appenders should implement this method to perform actual logging.
+     *
+     * @param LoggerLoggingEvent $event
+     */
+    abstract protected function append(LoggerLoggingEvent $event);
+
+    /**
+     * Releases any resources allocated by the appender.
+     *
+     * Derived appenders should override this method to perform proper closing
+     * procedures.
+     */
+    public function close() {
+        $this->closed = true;
+    }
+
+    /** Triggers a warning for this logger with the given message. */
+    protected function warn($message) {
+        $id = get_class($this) . (empty($this->name) ? '' : ":{$this->name}");
+        trigger_error("log4php: [$id]: $message", E_USER_WARNING);
+    }
+
+}