	Client-Server Programming Spring Semester, 2005 Configuration Files & Logging
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Doc 12 Configuration Files & Logging

Application Parameters & Configuration Files

sdsu.util.ProgramProperties

Example of Different Message Types

Logger Names

Sample Configuration File

Copyright ©, All rights reserved. 2005 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA. OpenContent ( http://www.opencontent.org/opl.shtml) license defines the copyright on this document.

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References

SDSU Java Library, http://www.eli.sdsu.edu/java-SDSU/docs/

Java Logging Overview, http://java.sun.com/j2se/1.4.2/docs/guide/util/logging/overview.html

Java Logging API http://java.sun.com/j2se/1.4.2/docs/api/java/util/logging/package-summary.html

Patterns for Logging Diagnostic Messages by Neil Harrison in Pattern Languages of Program Design 3 Eds Martin, Riehle, Buschman, 1998, pp 277-289

SDSU Java Library, http://www.eli.sdsu.edu/java-SDSU/docs/

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Application Parameters & Configuration Files

Applications normal have configuration files to store

User preferences
Cached values
Window settings
Port numbers
Database connection information
Log file information
Recent documents/web pages
Cookies
Values that need changing without recompiling

Some programs use environment variables

   cvs co assignment2

Command line program/servers/utilities have flags

   ls -la
   ps -aux

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Servers

Servers normally use configuration files & command line flags

Environment variables are uses much in servers (why?)

Flag values override configuration file values

Configuration file values override defaults in the code

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Java

Some systems have libraries to handle config files & command line arguments

JDK does not seem to have such classes

There should be a number of Java libraries that provide such support

sdsu Java library is one such library

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sdsu.util.ProgramProperties

Parses

Configuration files Command line arguments

Command Line argument

-flag=value-flag value -flag--xyz-- (ignore rest of the command line )

File Formats

properties format

#A comment to the end of the line
key1=value1
key2=value2 with spaces
key3 with spaces=value3 #part of the value

sdsu.util.LabeledData format

#A comment to the end of the line,
key1 = value1;
key2='value2 with spaces';
'key3 with spaces'=value3; # a comment

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Simple Example

import sdsu.util.ProgramProperties;
   
public class ConfigurationExample {
   
   public static void main(String args[]) {
      try
         {
         ProgramProperties flags = 
            new ProgramProperties( args, "configurationFile");
         String nameValue = 
            flags.getString( "name" , "No name given");
         int size = flags.getInt( "size", 0);
         boolean switchOn = flags.containsKey( "s");
         System.out.println( " nameValue: " + nameValue);
         System.out.println( " size: " + size);
         System.out.println( " switchOn: " + switchOn);
         
         }
      catch (java.io.IOException readParseProblem)
         {
         System.err.println( "Program aborted on error " + 
         readParseProblem);
         }
   }
}

File "configurationFile.labeledData"

name=Roger;
size=12;

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Sample Runs

java ConfigurationExample

Output

nameValue: Roger

size: 12

switchOn: false

java ConfigurationExample -s -name Pete

Output

nameValue: Pete

size: 12

switchOn: true

java ConfigurationExample -conf=otherFile

Output

nameValue: Sam

size: 8

switchOn: true

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Why logging?

Performance tuning
Upgrade justification
Problem tracking
Access counting

How many times was the assignment 1 server accessed?

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What should be logged?

Normally a log entry contains several pieces of information:

Date and time
Service that caused the entry
Client address that caused the entry
Host on which the server runs
Event

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Log File Examples

ApacheAccess

211.90.88.43 - - [21/Oct/2002:08:33:29 -0700] "GET /scripts/..%25%35%63../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 303
211.90.88.43 - - [21/Oct/2002:08:33:30 -0700] "GET /scripts/..%252f../winnt/system32/cmd.exe?/c+dir HTTP/1.0" 404 303

Error

[Mon Oct 21 08:33:29 2002] [error] [client 211.90.88.43] File does not exist: /opt/etc/apache-1.3.26/htdocs/scripts/..%5c../winnt/system32/cmd.exe
[Mon Oct 21 08:33:30 2002] [error] [client 211.90.88.43] File does not exist: /opt/etc/apache-1.3.26/htdocs/scripts/..%2f../winnt/system32/cmd.exe

Note that the log files contain the client IP address not the name of the machine

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Dnews – A News Server

Log files

dnews.in
dnews.log
dnews.out
dnews_post.log
expire.log
status.log
users.log

Configuration files

access.conf
control.conf
expire.conf
fts.conf
hp.conf
moderators.conf
newsfeeds.conf

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Dnews Log file examplesusers.log

Mon Oct 21 04:50:23 Bytes Read,  Current Connections,  Area/IPrange
Mon Oct 21 04:50:23       197k           1   194.170.42.68 
Mon Oct 21 04:50:23       197k           1   byu 
Mon Oct 21 04:50:23    0mb          2   Grand Totals

dnews.log

21 09:41:27  :info: db_piles_trim called
21 09:42:08  :info: db_pile_status
21 09:42:08  :info: db_pile_status_done
21 09:42:08  :info: dnews_status 1
21 09:42:08  :info: dnews_status 2
21 09:42:08  :info: dnews_status 3
21 09:42:08  :info: Timezone Offset 25200 dst 3600
21 09:42:16  :info: Writing list of read groups to a file for this slave
21 09:42:16  :info: Wrote 17 records
21 09:42:28  :info: db_piles_trim called

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Log file formats

Log files get big

Assignment1 log file was 12.8MB

Web server logs get 10 - 100 Mbs before rotating the file

Make the log file machine parsable!

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How should clients and servers log?

Basic choices:

Appending to a log file
System logging facility

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Simple appending problems

This simplistic approach can cause problems with the following:

Concurrency

Two server threads concurrently writing to the same logfile

Performance

Every log entry requires lots of overhead
(opening and closing the logfile)

Some solutions:

Rely on the OS to perform atomic appends to the log file.

(One unbuffered write per log entry)

Use a dedicated logging thread (Keep the log file open)

Synchronize the writing to the log file.

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JDK 1.4 Logging

Starting with JDK 1.4 Java API has a logging system

Supports

Multiple log levels
Multiple output formats
Output to different IO devices

Filters for additional filtering of message to accept
ResourceBundles for localization of log messages
Initialization of loggers by configuration file
Hierarchical loggers in one program

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Log Levels

ALL
SEVERE (highest value)
WARNING
INFO (usual default)
CONFIG
FINE
FINER
FINEST (lowest value)
OFF

Output formats

XML (default for files output)
Normal Text (default for screen output)

Output devices

Stream
System.err
File or rotating set of files
Socket for network logging
Memory

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SimpleExample

import java.util.logging.*;
   
public class SimpleLoggingExample 
   {
   private static Logger logger = Logger.getLogger("edu.sdsu.cs580");
      
    public static void main (String args[]) 
      {
      new SimpleLoggingExample().someLogMessages();
      }
   
   public void someLogMessages()
      {
      logger.severe( "A severe log message");
      Logger.getLogger("edu.sdsu.cs580").fine( "A fine message");
      logger.warning( "Be careful" ); 
      }
   }

Output To System.err

Feb 16, 2004 10:51:37 PM Logging someLogMessages

SEVERE: A severe log message

Feb 16, 2004 10:51:37 PM Logging someLogMessages

WARNING: Be careful

Default Settings

Use a ConsoleHandler

Level set to INFO

System administrator can change default settings

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Five Categories of Logging MessagesConvenience Methods

severe( String message);
warning( String message);
info( String message);
config( String message);
fine( String message);
finer( String message);
finest( String message);

Convenience Methods for Tracing Methods

entering(String sourceClass, String sourceMethod);

entering(String sourceClass, String sourceMethod, Object parameter);

entering(String sourceClass, String sourceMethod, Object[] parameters);

exiting(String sourceClass, String sourceMethod);

exiting(String sourceClass, String sourceMethod, Object result);

Log Methods

log(Level logLevel, String message);

log(Level logLevel, String message, Object parameter);

log(Level logLevel, String message, Object[] parameters);

log(Level logLevel, String message, Throwable exception);

Currently parameters argument is ignored

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Precise Log Methods

Add class and method to log messages

logp(Level logLevel, String class, String method,String message);

etc.

Logs with Resource Bundles

Add resource bundle to logp messages

logrb(Level logLevel, String class, String method, String bundlename,

String message);

etc.

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Example of Different Message Types

import java.io.*;
import java.util.Vector;
import java.util.logging.*;
   
public class MessageTypes 
   {
   private static Logger logger = Logger.getLogger("edu.sdsu.cs580");
   
   static
      {
      try
         {
         Handler textLog = new FileHandler("textLog.txt");
         textLog.setFormatter( new SimpleFormatter());
         textLog.setLevel(Level.ALL);
         Handler xmlLog = new FileHandler("xmlLog.txt");
         xmlLog.setFormatter( new XMLFormatter());
         xmlLog.setLevel(Level.ALL);
   
         logger.addHandler(textLog);
         logger.addHandler(xmlLog);
         logger.setLevel(Level.ALL);
         }
      catch (IOException fileError)
         {
         System.err.println( "Could not open log files");
         }
      }

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Example Continued

public static void main (String args[]) 
      {
      new MessageTypes().someLogMessages();
      }
   
   public void someLogMessages()
      {
      logger.entering("MessageTypes", "someLogMessages");
         Vector data = new Vector();
      data.add( "Cat");
      logger.log(Level.SEVERE, "Show Vector", data); 
      logger.severe( "A severe log message");
      logger.logp(Level.SEVERE, "MessageTypes", "someLogMessages", "Logp example");
      try
         {
         int zeroDivide = 1/ (1 - 1);
         }
      catch (Exception zeroDivide)
         {
         logger.log(Level.SEVERE, "Exception example", zeroDivide);
         }
    logger.exiting("MessageTypes", "someLogMessages");
      }
   }
CS 580 Spring 05 Doc 12, Configuration Files & Logging Slide # 24

SimpleFormatter Output

Feb 16, 2004 11:01:53 PM MessageTypes someLogMessages

FINER: ENTRY

Feb 16, 2004 11:01:53 PM MessageTypes someLogMessages

SEVERE: Show Vector

Feb 16, 2004 11:01:53 PM MessageTypes someLogMessages

SEVERE: A severe log message

Feb 16, 2004 11:01:54 PM MessageTypes someLogMessages

SEVERE: Logp example

Feb 16, 2004 11:01:54 PM MessageTypes someLogMessages

SEVERE: Exception example

java.lang.ArithmeticException: / by zero

at MessageTypes.someLogMessages(MessageTypes.java:45)

at MessageTypes.main(MessageTypes.java:32)

Feb 16, 2004 11:01:54 PM MessageTypes someLogMessages

FINER: RETURN

XMLFormatter Sample Output

<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
<!DOCTYPE log SYSTEM "logger.dtd">
<log>
<record>
  <date>2004-02-16T23:01:53</date>
  <millis>1077001313695</millis>
  <sequence>0</sequence>
  <logger>edu.sdsu.cs580</logger>
  <level>FINER</level>
  <class>MessageTypes</class>
  <method>someLogMessages</method>
  <thread>10</thread>
  <message>ENTRY</message>
</record>

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FileHandlers

Can be set to rotate files

Can be located in temp directory

Can be set to

Append existing files
Overwrite existing files (default)

To change append setting either

Use constructor

      FileHandler(String pattern, boolean append)

Or use configuration file

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Loggers

Can have

Multiple handlers

Multiple handlers of same type

Loggers and handlers have differ log levels

Logger

Drops all messages below it log level
Passes remaining messages to all handlers
Handler can further drop more messages

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Logger Names

Logger names are arbitrary

   Logger.getLogger("edu.sdsu.cs580")
   Logger.getLogger("foo")
   Logger.getLogger("")

Sun recommends using hierarchical names with format

"domain.package"

"domain.package.class"

Loggers inherit settings from “parent” logger

Logger "edu.sdsu.cs580" would inherit settings of "edu.sdsu"

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Debug Example

import java.io.*;
import java.util.logging.*;
public class Logging 
   {
   private static Logger logger = Logger.getLogger("edu.sdsu.cs580");
   private static Logger debug = Logger.getLogger("debug");
   // screen loging is default, as in INFO level
   
   static
      {
      try
         {
         // Parent sends log to the screen
         logger.setUseParentHandlers( false);
   
         Handler textLog = new FileHandler("textLog.txt");
         textLog.setLevel(Level.ALL);
      
         logger.addHandler(textLog);
         logger.setLevel(Level.ALL);
            
         debug.setUseParentHandlers( false);
         Handler screenLog = new ConsoleHandler();
         debug.addHandler( screenLog);
         debug.setLevel( Level.INFO );
         }
      catch (IOException fileError)
         {
         System.err.println( "Could not open log files");
         }
      }

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Example continued

   public static void main (String args[]) 
      {
      new Logging().someLogMessages();
      }
      
   public void someLogMessages()
      {
      logger.info( "A severe log message");
      debug.info( "this is a debug statement");      
      }
   }

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Logger Scope

Logger settings can be defined in

Program
Configuration File

Logger settings defined in a program exist only in that program

Logger settings defined in a configuration file can be used by multiple programs

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Sample Configuration File

# Use two loggers
handlers= java.util.logging.FileHandler, java.util.logging.ConsoleHandler
   
# Default global logging level.
.level= WARNING 
   
# File logger default settings
# Default file output is in user's home directory (%h/).
# %g – use generation numbers to distinguish rotated logs
# limit = max size of each log file
# count = number of output files to cycle through
java.util.logging.FileHandler.pattern = %h/cs580Server%g.log
java.util.logging.FileHandler.limit = 50000
java.util.logging.FileHandler.count = 3
java.util.logging.FileHandler.formatter = java.util.logging.XMLFormatter
   
# Limit the message that are printed on the console to INFO and above.
java.util.logging.ConsoleHandler.level = INFO
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
   
# Set levels of specific loggers
edu.sdsu.level = SEVERE
edu.sdsu.cs580.level = INFO

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Using the Configuration File

Assume that configuration file is in

Local directory
In a file called cs580Log.properties

The following command will use the configuration file

java -Djava.util.logging.config.file=cs580Log.properties  yourClassGoesHere

2005 SDSU & Roger Whitney, 5500 Campanile Drive, San Diego, CA 92182-7700 USA.

OpenContent license defines the copyright on this document.

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Doc 12 Configuration Files & Logging

Contents

References

Application Parameters & Configuration Files

Servers

Java

sdsu.util.ProgramProperties

File Formats

File "configurationFile.labeledData"

Sample Runs

Output

Output

Output

Why logging?

What should be logged?

Log File Examples

ApacheAccess

Error

Dnews – A News Server

Dnews Log file examplesusers.log

dnews.log

Log file formats

How should clients and servers log?

Simple appending problems

JDK 1.4 Logging

Log Levels

Output formats

Output devices

SimpleExample

Output To System.err

Default Settings

Five Categories of Logging MessagesConvenience Methods

Convenience Methods for Tracing Methods

Log Methods

Precise Log Methods

Logs with Resource Bundles

Example of Different Message Types

Example Continued

SimpleFormatter Output

XMLFormatter Sample Output

FileHandlers

Loggers

Logger Names

Debug Example

Example continued

Logger Scope

Sample Configuration File

Using the Configuration File