// Logger.java// $Id: Logger.java,v 1.6 2003/05/13 17:48:55 ylafon Exp $// (c) COPYRIGHT MIT and INRIA, 1996.// Please first read the full copyright statement in file COPYRIGHT.htmlpackage org.w3c.jigsaw.http ;/** * The Logger class is the abstract class that loggers must implement.  * You can (should be able to) use several loggers at the same time. */abstract public class Logger {    /**     * Log normally a full handled request.      * @param client The client which made the request.     * @param request The request that was handled.     * @param reply The emitted reply to the client.     * @param nbytes The number of bytes sent to this client.     * @param duration The time it took to process the request.     */    abstract    public void log (Request request		     , Reply reply		     , int nbytes		     , long duration) ;    /**     * Log a message to the log.     * @param msg The message to log.     */    abstract    public void log(String msg);    /**     * Log an error on behalf of some client object in the error log.      * @param client The client for which the error occured.      * @param msg The error message to log.       */    abstract    public void errlog (Client client, String msg) ;    /**     * Log an error on behalf of the server object.     * @param msg The message to emit.     */    abstract     public void errlog (String msg) ;    /**     * Log a client trace. The client may be in some error state, so all access     * to the client parameter should be checked.     * @param client The client that wants to emit a trace.     * @param trace The trace to log.     */    abstract    public void trace (Client client, String trace) ;    /**     * Log a server trace.     * @param msg The trace to emit.     */    abstract    public void trace (String msg) ;    /**     * Flush any in core logger state back to disk.     * Some loggers may use memory cache before writing any data to the disk     * this method ensures that there state is saved to stable storage.     */    abstract     public void sync();    /**     * Shutdown this logger object.     * Each server will close the shutdown method of the logger before     * shuting itself down.     */    abstract    public void shutdown() ;    /**     * Initialize this logger for the provided server.     * No call to any methods of the logger will be made before this      * logger is initialized for some server.     * @param server The server to which this logger should be initialized.     */    abstract     public void initialize (httpd server) ;    /**     * Construct a new Logger instance.     */    public Logger () {    }}