--- /dev/null
+/*
+ * 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 org.apache.log4j.spi;
+
+/**
+
+ Implementions of this interface allow certain appenders to decide
+ when to perform an appender specific action.
+
+ <p>For example the {@link org.apache.log4j.net.SMTPAppender} sends
+ an email when the {@link #isTriggeringEvent} method returns
+ <code>true</code> and adds the event to an internal buffer when the
+ returned result is <code>false</code>.
+
+ @author Ceki Gülcü
+ @since version 1.0
+
+ */
+public interface TriggeringEventEvaluator {
+
+ /**
+ Is this the triggering event?
+ */
+ public boolean isTriggeringEvent(LoggingEvent event);
+}