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 * 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
 *
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 * distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.logging.log4j.core;

import java.io.Serializable;

Appends LogEvents. An Appender can contain a Layout if applicable as well as an ErrorHandler. Typical Appender implementations coordinate with an implementation of AbstractManager to handle external resources such as streams, connections, and other shared state. As Appenders are plugins, concrete implementations need to be annotated with Plugin and need to provide a static factory method annotated with PluginFactory. 
Most core plugins are written using a related Manager class that handle the actual task of serializing a LogEvent to some output location. For instance, many Appenders can take advantage of the OutputStreamManager class.
It is recommended that Appenders don't do any heavy lifting since there can be many instances of the class being used at any given time. When resources require locking (e.g., through FileLock), it is important to isolate synchronized code to prevent concurrency issues.
/**
 * Appends {@link LogEvent}s. An Appender can contain a {@link Layout} if applicable as well
 * as an {@link ErrorHandler}. Typical Appender implementations coordinate with an
 * implementation of {@link org.apache.logging.log4j.core.appender.AbstractManager} to handle external resources
 * such as streams, connections, and other shared state. As Appenders are plugins, concrete implementations need to
 * be annotated with {@link org.apache.logging.log4j.core.config.plugins.Plugin} and need to provide a static
 * factory method annotated with {@link org.apache.logging.log4j.core.config.plugins.PluginFactory}.
 *
 * <p>Most core plugins are written using a related Manager class that handle the actual task of serializing a
 * {@link LogEvent} to some output location. For instance, many Appenders can take
 * advantage of the {@link org.apache.logging.log4j.core.appender.OutputStreamManager} class.</p>
 *
 * <p>It is recommended that Appenders don't do any heavy lifting since there can be many instances of the class
 * being used at any given time. When resources require locking (e.g., through {@link java.nio.channels.FileLock}),
 * it is important to isolate synchronized code to prevent concurrency issues.</p>
 */
public interface Appender extends LifeCycle {

    
Main plugin element type for Appender plugins. 
Since:
2.6/**
     * Main {@linkplain org.apache.logging.log4j.core.config.plugins.Plugin#elementType() plugin element type} for
     * Appender plugins.
     *
     * @since 2.6
     */
    String ELEMENT_TYPE = "appender";

    
Logs a LogEvent using whatever logic this Appender wishes to use. It is typically recommended to use a
bridge pattern not only for the benefits from decoupling an Appender from its implementation, but it is also
handy for sharing resources which may require some form of locking.
Params:
event – The LogEvent./**
     * Logs a LogEvent using whatever logic this Appender wishes to use. It is typically recommended to use a
     * bridge pattern not only for the benefits from decoupling an Appender from its implementation, but it is also
     * handy for sharing resources which may require some form of locking.
     *
     * @param event The LogEvent.
     */
    void append(LogEvent event);


    
Gets the name of this Appender.
Returns:
name, may be null./**
     * Gets the name of this Appender.
     *
     * @return name, may be null.
     */
    String getName();

    
Returns the Layout used by this Appender if applicable.
Returns:
the Layout for this Appender or null if none is configured./**
     * Returns the Layout used by this Appender if applicable.
     *
     * @return the Layout for this Appender or {@code null} if none is configured.
     */
    Layout<? extends Serializable> getLayout();

    
Some Appenders need to propagate exceptions back to the application. When ignoreExceptions is false the AppenderControl will allow the exception to percolate. 
Returns:
true if exceptions will be logged but not thrown, false otherwise./**
     * Some Appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
     * {@code false} the AppenderControl will allow the exception to percolate.
     *
     * @return {@code true} if exceptions will be logged but not thrown, {@code false} otherwise.
     */
    boolean ignoreExceptions();

    
Gets the ErrorHandler used for handling exceptions. 
Returns:
the ErrorHandler for handling exceptions./**
     * Gets the {@link ErrorHandler} used for handling exceptions.
     *
     * @return the ErrorHandler for handling exceptions.
     */
    ErrorHandler getHandler();

    
Sets the ErrorHandler used for handling exceptions. 
Params:
handler – the ErrorHandler to use for handling exceptions./**
     * Sets the {@link ErrorHandler} used for handling exceptions.
     *
     * @param handler the ErrorHandler to use for handling exceptions.
     */
    void setHandler(ErrorHandler handler);
}