UnboundID Server SDK

UnboundID Server SDK Documentation

ExampleHTTPOperationLogger.java

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 * CDDL HEADER START
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 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at
 * docs/licenses/cddl.txt
 * or http://www.opensource.org/licenses/cddl1.php.
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 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at
 * docs/licenses/cddl.txt.  If applicable,
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 *      Copyright 2010-2014 UnboundID Corp.
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package com.unboundid.directory.sdk.examples;



import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Date;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.unboundid.directory.sdk.common.api.DiskSpaceConsumer;
import com.unboundid.directory.sdk.common.types.RegisteredDiskSpaceConsumer;
import com.unboundid.directory.sdk.http.api.HTTPOperationLogger;
import com.unboundid.directory.sdk.http.config.HTTPOperationLoggerConfig;
import com.unboundid.directory.sdk.http.types.HTTPServerContext;
import com.unboundid.ldap.sdk.LDAPException;
import com.unboundid.ldap.sdk.ResultCode;
import com.unboundid.util.StaticUtils;
import com.unboundid.util.args.ArgumentException;
import com.unboundid.util.args.ArgumentParser;
import com.unboundid.util.args.FileArgument;



/**
 * This class provides a simple example of an HTTP operation logger that will
 * append a message to a specified file for any type of operation.  It takes a
 * single configuration argument:
 * <UL>
 *   <LI>log-file -- The path to the log file that will be written.  This must
 *       be provided.</LI>
 * </UL>
 */
public final class ExampleHTTPOperationLogger
       extends HTTPOperationLogger
       implements DiskSpaceConsumer
{
  /**
   * The name of the argument that will be used for the argument used to specify
   * the path to the log file.
   */
  private static final String ARG_NAME_LOG_FILE = "log-file";



  // The current general configuration for this HTTP operation logger.
  private volatile HTTPOperationLoggerConfig config;

  // The path to the log file to be written.
  private volatile File logFile;

  // The lock that will be used to synchronize logging activity.
  private final Object loggerLock;

  // The print writer that will be used to actually write the log messages.
  private volatile PrintWriter writer;

  // The registered disk space consumer for this logger.
  private volatile RegisteredDiskSpaceConsumer registeredConsumer;

  // The server context for the server in which this extension is running.
  private HTTPServerContext serverContext;



  /**
   * Creates a new instance of this HTTP operation logger.  All HTTP operation
   * logger implementations must include a default constructor, but any
   * initialization should generally be done in the
   * {@code initializeHTTPOperationLogger} method.
   */
  public ExampleHTTPOperationLogger()
  {
    loggerLock = new Object();
  }



  /**
   * Retrieves a human-readable name for this extension.
   *
   * @return  A human-readable name for this extension.
   */
  @Override()
  public String getExtensionName()
  {
    return "Example HTTP Operation Logger";
  }



  /**
   * Retrieves a human-readable description for this extension.  Each element
   * of the array that is returned will be considered a separate paragraph in
   * generated documentation.
   *
   * @return  A human-readable description for this extension, or {@code null}
   *          or an empty array if no description should be available.
   */
  @Override()
  public String[] getExtensionDescription()
  {
    return new String[]
    {
      "This HTTP operation logger serves an example that may be used to " +
           "demonstrate the process for creating a third-party HTTP " +
           "operation logger.  It will write a line to a specified file for " +
           "each HTTP operation processed.",

      "For simplicity, this example logger does not take care of all tasks " +
           "that would be necessary for production use.  For example, it " +
           "does not include any rotation or retention functionality, so the " +
           "file will grow without bounds.  Further, while it is threadsafe, " +
           "it does so using simple Java synchronized blocks which is a " +
           "simple way to achieve the necessary safety, but does not " +
           "necessarily allow for the highest performance or concurrency.",

      "Because this HTTP operation logger writes to disk, it also serves as " +
           "an example of a disk space consumer so that the server may track " +
           "available space on the disk containing the log file and " +
           "potentially warn administrators if usable space becomes too low."
    };
  }



  /**
   * Updates the provided argument parser to define any configuration arguments
   * which may be used by this HTTP operation logger.  The argument parser may
   * also be updated to define relationships between arguments (e.g., to specify
   * required, exclusive, or dependent argument sets).
   *
   * @param  parser  The argument parser to be updated with the configuration
   *                 arguments which may be used by this HTTP operation logger.
   *
   * @throws  ArgumentException  If a problem is encountered while updating the
   *                             provided argument parser.
   */
  @Override()
  public void defineConfigArguments(final ArgumentParser parser)
         throws ArgumentException
  {
    // Add an argument that allows you to specify the path to the log file.
    Character shortIdentifier = null;
    String    longIdentifier  = ARG_NAME_LOG_FILE;
    boolean   required        = true;
    int       maxOccurrences  = 1;
    String    placeholder     = "{path}";
    String    description     = "The path to the log file to be written.  " +
         "Non-absolute paths will be treated as relative to the server root.";
    boolean   fileMustExist   = false;
    boolean   parentMustExist = true;
    boolean   mustBeFile      = true;
    boolean   mustBeDirectory = false;

    parser.addArgument(new FileArgument(shortIdentifier, longIdentifier,
         required, maxOccurrences, placeholder, description, fileMustExist,
         parentMustExist, mustBeFile, mustBeDirectory));
  }



  /**
   * Initializes this HTTP operation logger.
   *
   * @param  serverContext  A handle to the server context for the server in
   *                        which this extension is running.
   * @param  config         The general configuration for this HTTP operation
   *                        logger.
   * @param  parser         The argument parser which has been initialized from
   *                        the configuration for this HTTP operation logger.
   *
   * @throws  LDAPException  If a problem occurs while initializing this HTTP
   *                         operation logger.
   */
  @Override()
  public void initializeHTTPOperationLogger(
                   final HTTPServerContext serverContext,
                   final HTTPOperationLoggerConfig config,
                   final ArgumentParser parser)
         throws LDAPException
  {
    this.serverContext = serverContext;
    this.config        = config;


    // Create the logger and open the log file.
    try
    {
      final FileArgument arg =
           (FileArgument) parser.getNamedArgument(ARG_NAME_LOG_FILE);
      logFile = arg.getValue();
      writer  = new PrintWriter(new FileWriter(logFile, true), true);
    }
    catch (final Exception e)
    {
      serverContext.debugCaught(e);
      throw new LDAPException(ResultCode.OTHER,
           "Unable to open file " + logFile.getAbsolutePath() +
                " for writing:  " + StaticUtils.getExceptionMessage(e),
           e);
    }


    // Register as a disk space consumer since the log file may potentially
    // consume a significant amount of disk space.
    registeredConsumer = serverContext.registerDiskSpaceConsumer(this);
  }



  /**
   * Indicates whether the configuration contained in the provided argument
   * parser represents a valid configuration for this extension.
   *
   * @param  config               The general configuration for this HTTP
   *                              operation logger.
   * @param  parser               The argument parser which has been initialized
   *                              with the proposed configuration.
   * @param  unacceptableReasons  A list that can be updated with reasons that
   *                              the proposed configuration is not acceptable.
   *
   * @return  {@code true} if the proposed configuration is acceptable, or
   *          {@code false} if not.
   */
  @Override()
  public boolean isConfigurationAcceptable(
                      final HTTPOperationLoggerConfig config,
                      final ArgumentParser parser,
                      final List<String> unacceptableReasons)
  {
    // The argument parser will handle all of the necessary validation, so
    // we don't need to do anything here.
    return true;
  }



  /**
   * Attempts to apply the configuration contained in the provided argument
   * parser.
   *
   * @param  config                The general configuration for this HTTP
   *                               operation logger.
   * @param  parser                The argument parser which has been
   *                               initialized with the new configuration.
   * @param  adminActionsRequired  A list that can be updated with information
   *                               about any administrative actions that may be
   *                               required before one or more of the
   *                               configuration changes will be applied.
   * @param  messages              A list that can be updated with information
   *                               about the result of applying the new
   *                               configuration.
   *
   * @return  A result code that provides information about the result of
   *          attempting to apply the configuration change.
   */
  @Override()
  public ResultCode applyConfiguration(final HTTPOperationLoggerConfig config,
                                       final ArgumentParser parser,
                                       final List<String> adminActionsRequired,
                                       final List<String> messages)
  {
    this.config = config;

    // Get the path to the log file from the new config.
    final FileArgument arg =
         (FileArgument) parser.getNamedArgument(ARG_NAME_LOG_FILE);
    final File newFile = arg.getValue();

    // If the log file path hasn't changed, then we don't need to do anything.
    if (newFile.equals(logFile))
    {
      return ResultCode.SUCCESS;
    }

    // Create a print writer that can be used to write to the new log file.
    final PrintWriter newWriter;
    try
    {
      newWriter = new PrintWriter(new FileWriter(newFile, true), true);
    }
    catch (final Exception e)
    {
      serverContext.debugCaught(e);
      messages.add("Unable to open new log file " + newFile.getAbsolutePath() +
           " for writing:  " + StaticUtils.getExceptionMessage(e));
      return ResultCode.OTHER;
    }

    // Swap the new logger into place.
    final PrintWriter oldWriter;
    synchronized (loggerLock)
    {
      oldWriter = writer;
      writer = newWriter;
      logFile = newFile;
    }

    // Close the old logger and return success.
    oldWriter.close();
    return ResultCode.SUCCESS;
  }



  /**
   * Performs any cleanup which may be necessary when this HTTP operation logger
   * is to be taken out of service.
   */
  @Override()
  public void finalizeHTTPOperationLogger()
  {
    synchronized (loggerLock)
    {
      if (registeredConsumer != null)
      {
        serverContext.deregisterDiskSpaceConsumer(registeredConsumer);
        registeredConsumer = null;
      }

      writer.close();
      writer = null;
      logFile = null;
    }
  }



  /**
   * Logs information about a servlet request that has been received from the
   * client.
   *
   * @param  request   An object with information about the request received
   *                   from the client.
   * @param  stateMap  An empty map which may be updated to hold state
   *                   information that can be used to correlate information
   *                   between the request and response.  The same map instance
   *                   will be passed to the {@link #logResponse} method.
   */
  @Override()
  public void logRequest(final HttpServletRequest request,
                         final Map<String,Object> stateMap)
  {
    // All of the processing for this logger will be done during the course of
    // handling the response.
  }



  /**
   * Logs information about a servlet response to be returned to the client.
   *
   * @param  request   An object with information about the request received
   *                   from the client.
   * @param  response  An object with information about the response to be
   *                   returned to the client.
   * @param  stateMap  A map containing state any information added while
   *                   processing the {@link #logRequest} method.
   */
  @Override()
  public void logResponse(final HttpServletRequest request,
                          final HttpServletResponse response,
                          final Map<String,Object> stateMap)
  {
    final Long processingTimeMillis =
         (Long) stateMap.get(STATE_KEY_PROCESSING_TIME_MILLIS);
    final Long bytesSent =
         (Long) stateMap.get(STATE_KEY_RESPONSE_CONTENT_LENGTH);

    final StringBuilder buffer = new StringBuilder();
    buffer.append(new Date().toString());
    buffer.append(' ');
    buffer.append("request=\"");
    buffer.append(request.getMethod());
    buffer.append(' ');
    buffer.append(request.getRequestURI());

    if (request.getMethod().equals("GET"))
    {
      final String queryString = request.getQueryString();
      if ((queryString != null) && (queryString.length() > 0))
      {
        buffer.append('?');
        buffer.append(queryString);
      }
    }

    buffer.append(' ');
    buffer.append(request.getProtocol());
    buffer.append("\" statusCode=");
    buffer.append(response.getStatus());
    buffer.append(" bytesSent=");
    buffer.append(bytesSent);
    buffer.append(" processingTimeMillis=");
    buffer.append(processingTimeMillis);

    synchronized (loggerLock)
    {
      if (writer == null)
      {
        // This should only happen if the logger has been shut down.
        return;
      }

      writer.println(buffer.toString());
      writer.flush();
    }
  }



  /**
   * Retrieves a map containing examples of configurations that may be used for
   * this extension.  The map key should be a list of sample arguments, and the
   * corresponding value should be a description of the behavior that will be
   * exhibited by the extension when used with that configuration.
   *
   * @return  A map containing examples of configurations that may be used for
   *          this extension.  It may be {@code null} or empty if there should
   *          not be any example argument sets.
   */
  @Override()
  public Map<List<String>,String> getExamplesArgumentSets()
  {
    final LinkedHashMap<List<String>,String> exampleMap =
         new LinkedHashMap<List<String>,String>(1);

    exampleMap.put(
         Arrays.asList(ARG_NAME_LOG_FILE + "=logs/example-http-access.log"),
         "Write HTTP operation log messages to the " +
              "logs/example-http-access.log file below the server root.");

    return exampleMap;
  }



  /**
   * Retrieves the name that should be used to identify this disk space
   * consumer.
   *
   * @return  The name that should be used to identify this disk space consumer.
   */
  public String getDiskSpaceConsumerName()
  {
    return "Example HTTP Operation Logger " + config.getConfigObjectName();
  }



  /**
   * Retrieves a list of filesystem paths in which this disk space consumer may
   * store files which may consume a significant amount of space.  It is
   * generally recommended that the paths be directories, but they may also be
   * individual files.
   *
   * @return  A list of filesystem paths in which this disk space consumer may
   *          store files which may consume a significant amount of space.
   */
  public List<File> getDiskSpaceConsumerPaths()
  {
    return Arrays.asList(logFile);
  }
}