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log


Resin can perform access logging, specify where JDK logging interface messages go, and redirect the stderr and stdout for your applications.

java.util.logging

Logger: Application logging

You can take advantage of the JDK's logging facility to add logging to your application. Choosing a good logging name and levels are important for troubleshooting and debugging your code. Logging to much can be almost as confusing as logging too little.

The logging name should be the full class name of the class you're instrumenting. Although other schemes are possible, the class name is more maintainable.

The logging level should be consistent across your application. For Resin, we use the following level conventions:

Example: logging at finer
import java.util.logging.Logger;
import java.util.logging.Level;

public class Foo {
  private static final Logger log
    = Logger.getLogger(Foo.class.getName());

  ...
  void doFoo(String bar)
  {
    // check for log level if your logging call does anything more
    // than pass parameters
    if (log.isLoggable(Level.FINER))
        log.finer(this + "doFoo(" + bar + ")");

    ...

    log.info(...);

    try {
        ...
    } catch (ExpectedException ex) {
      log.log(Level.FINEST, "expected exception", ex);
    }
  }
  ...
}

Log names

The JDK logging api uses a hierarchical naming scheme. Typically the name is aligned with a java class name. When you specify a name, all logging requests that use a name that starts with the name you have specified are matched. For example: <logger name="example.hogwarts" ...> matches a logging request for both "example.hogwarts.System" and "example.hogwarts.gryffindor.System"

Resin's logging is based on Resin's source class names. The following are useful logs.

Resin log names
NAMEMEANING
""Debug everything
com.caucho.amberAmber (JPA) handling
com.caucho.ejbEJB handling
com.caucho.jspDebug jsp
com.caucho.javaJava compilation
com.caucho.server.portTCP port debugging and threading
com.caucho.server.port.AcceptPoolport thread creation
com.caucho.server.httpHTTP-related debugging
com.caucho.server.webappweb-app related debugging
com.caucho.server.cacheCache related debugging
com.caucho.sqlDatabase pooling
com.caucho.transactionTransaction handling

Log levels

The level for log tags matches the levels in the JDK .

Logging Level values
NAMEAPISUGGESTED USE
off turn off logging
severelog.severe("...")a major failure which prevents normal program execution, e.g. a web-app failing to start or a server restart
warninglog.warning("...")a serious issue, likely causing incorrect behavior, like a 500 response code to a browser
infolog.info("...")major lifecycle events, like a web-app starting
configlog.config("...")detailed configuration logging
finelog.fine("...")debugging at an administrator level, i.e. for someone not familiar with the source code being debugged
finerlog.finer("...")detailed debugging for a developer of the code being debugged
finestlog.finest("...")events not normally debugged, e.g. expected exceptions logged to avoid completely swallowing, or Hessian or XML protocol parsing
all all messages should be logged

<log-handler>

child of resin, server, host-default, host, web-app-default, web-app

Configure a log handler for the JDK java.util.logging.* API. java.util.logging has two steps: configure a set of log handlers, and configure the levels for each logger. The <log-handler> creates a destination for logs, sets a minimum logging level for the handler, and attaches the handler to a logging name.

In addition to configuring custom handlers, <log-handler> has the most common configuration build-in: logging to a rotating file. Most of the configuration attributes are used for the rotating file and are shared with the other logging configuration.

<log-handler> values
ATTRIBUTEDESCRIPTIONDEFAULT
archive-formatthe format for the archive filename when a rollover occurs, see Rollovers. see below
classconfigures a custom Handler class
formatterConfigures a custom java.util.logging.Formatter to format the output.
initIoC-style initialization configuration for the formatter.
levelThe log level for the handler. Typically, the handler's level will be finer than the logger's levelinfo
mbean-namean mbean name, see MBean control.no mbean name, no mbean registration
nameA hierarchical name, typically aligned with the Java packaging names. The handler will be registered with the Logger with the matching name.match all names
pathOutput path for the log messages, see "Log Paths"required
path-formatSelects a format for generating path names. The syntax is the same as for archive-formatoptional
timestampa timestamp format string to use at the beginning of each log line. "[%Y/%m/%d %H:%M:%S.%s] "
rollover-countmaximum number of rollover files before the oldest ones get overwritten. See Rollovers. none
rollover-periodhow often to rollover the log. Specify in days (15D), weeks (2W), months (1M), or hours (1h). See Rollovers. none
rollover-sizemaximum size of the file before a rollover occurs, in bytes (50000), kb (128kb), or megabytes (10mb). See Rollovers. 1mb
uriconfigures a symbolic alias for the handler's class. The handler implementer will register the schema
<log-handler> schema
element log-handler {
  archive-format?
  & class?
  & filter?
  & format?
  & formatter?
  & init?
  & level?
  & mbean-name?
  & name
  & path?
  & path-format?
  & rollover-count?
  & rollover-period?
  & rollover-size?
  & timestamp?
  & uri?
  & use-parent-handlers?
}

The following example sends warning messages to a JMS queue. The uri="jms:" is an alias for com.caucho.log.handler.JmsHandler. The uri="timestamp:" is a formatter alias for com.caucho.log.formatter.TimestampFormatter

Example: logging to a JMS queue
<web-app xmlns="http://caucho.com/ns/resin">

  <jms-queue name="myQueue" uri="memory:"/>

  <log-handler name="qa.test" level="warning" uri="jms:">
    <init target="${myQueue}"/>

    <formatter uri="timestamp:"/>
  </log-handler>

</web-app>

The following example is a standard log handler writing to a rollover file. Because the handler's level is "all", the <logger> configuration will set the actual logging level.

Example: logging to a rollover file
<web-app xmlns="http://caucho.com/ns/resin">

  <jms-queue name="myQueue" uri="memory:"/>

  <log-handler name="" level="all"
       timestamp="[%Y/%m/%d %H:%M:%S.%s] {%{thread}} "/>

  <logger name="com.caucho" level="info"/>

</web-app>

<log>

child of resin, server, host-default, host, web-app-default, web-app

Configure the amount and destination of debug logging for the JDK java.util.logging.* API.

<log> values
ATTRIBUTEDESCRIPTIONDEFAULT
nameA hierarchical name, typically aligned with the Java packaging namesmatch all names
levelThe log levelinfo
pathOutput path for the log messages, see "Log Paths"required
path-formatSelects a format for generating path names. The syntax is the same as for archive-formatoptional
timestampa timestamp format string to use at the beginning of each log line. "[%Y/%m/%d %H:%M:%S.%s] "
formata format string to control the output of each log message. Since Resin 3.0.5. ${log.message}
rollover-countmaximum number of rollover files before the oldest ones get overwritten. See Rollovers. none
rollover-periodhow often to rollover the log. Specify in days (15D), weeks (2W), months (1M), or hours (1h). See Rollovers. none
rollover-sizemaximum size of the file before a rollover occurs, in bytes (50000), kb (128kb), or megabytes (10mb). See Rollovers. 1mb
archive-formatthe format for the archive filename when a rollover occurs, see Rollovers. see below
mbean-namean mbean name, see MBean control.no mbean name, no mbean registration
handleradd a custom Handler, the name of a class that extends  
formatterset a custom Formatter, the name of a class that extends none, or if format is used.

The default archive format is

default archive-format
path + ".%Y%m%d"    if rollover-period >= 1 day.
path + ".%Y%m%d.%H" if rollover-period < 1 day.

For example, to log everything to standard error use:

Example: logging everything to System.err
<resin xmlns="http://caucho.com/ns/resin">
  <log name='' level='all' path='stderr:' timestamp="[%H:%M:%S.%s]"/>
  ...
</resin>

A useful technique is to enable full debug logging to track down a problem:

debug logging

<resin>
  ...
  <log name='' level='finer' path='log/debug.log'
       timestamp="[%H:%M:%S.%s]"
       rollover-period='1h' rollover-count='1'/>
  ...
</resin>

More examples of debug logging are in the Troubleshooting section.

The class that corresponds to <log> is .

Log format string

The format for log tags is used to specify a format string for each log message. format recognizes EL-expressions. The EL variable log is a object.

log format string

<log name='' level='all' path='stderr:' timestamp="[%H:%M:%S.%s]"
     format=" ${log.level} ${log.loggerName} ${log.message}"/>

log EL variable 'log' is a LogRecord
ACCESSORVALUE
${log.level}The level of the log record
${log.name}The source loggers name
${log.shortName}A shorter version of the source loggers name, "Foo" instead of "com.hogwarts.Foo"
${log.message}The message, with no formatting or localization
${log.millis}event time in milliseconds since 1970
${log.sourceClassName}Get the name of the class that issued the logging request (may not be available at runtime)
${log.sourceMethodName}Get the name of the method that issued the logging request (may not be available at runtime)
${log.threadID}Get an int identifier of the thread where the logging request originated
${log.thrown}Get any associated with the logging request

You can also use the Environment EL variables in your format string:

log format string using an Environment EL variable.
<host ...>

  <web-app>
    <log name='' level='all' path='log/debug.log' timestamp="[%H:%M:%S.%s]"
         format=" [${'${'}app.contextPath}] ${'${'}log.message}"/>

    ...
  </web-app>

  ...

</host>
[14:55:10.189] [/foo] `null' returning JNDI java:
       model for EnvironmentClassLoader[web-app:http://localhost:8080/foo]
[14:55:10.189] [/foo] JNDI lookup `java:comp/env/caucho/auth'
       exception javax.naming.NameNotFoundException: java:comp/env/caucho/auth
[14:55:10.199] [/foo] Application[http://localhost:8080/foo] starting

The fmt.sprintf() function can space pad the values and make the results look a little nicer:

fmt.sprintf() in log format string
<log name='' level='all' path='stderr:' timestamp="[%H:%M:%S.%s]"
     format=" ${fmt.sprintf('%-7s %45s %s',log.level,log.loggerName,log.message)}"/>
[14:28:08.137] INFO com.caucho.vfs.QJniServerSocket Loaded Socket JNI library.
[14:28:08.137] INFO com.caucho.server.port.Port http listening to *:8080
[14:28:08.137] INFO com.caucho.server.resin.ServletServer ServletServer[] starting
[14:28:08.307] INFO com.caucho.server.port.Port hmux listening to localhost:6802
[14:28:08.437] INFO com.caucho.server.host.Host Host[] starting 

fmt.sprintf() and fmt.timestamp() can be used to produce CSV files:

CSV log files
<log name='' level='all' path='log/debug.csv' timestamp=""
     format="${fmt.sprintf('%vs,%d,%d,%vs,%vs',fmt.timestamp('%Y-%m-%d %H:%M:%S.%s'), 
               log.threadID, log.level.intLevel(), log.loggerName, log.message)}"/>
"2003-11-17 14:46:14.529",10,800,"com.caucho.vfs.QJniServerSocket",
            "Loaded Socket JNI library."
"2003-11-17 14:46:14.549",10,800,"com.caucho.server.port.Port",
            "http listening to *:8080"
"2003-11-17 14:46:14.549",10,800,"com.caucho.server.resin.ServletServer",
            "ServletServer[] starting"
"2003-11-17 14:46:14.719",10,800,"com.caucho.server.port.Port",
            "hmux listening to localhost:6802"
"2003-11-17 14:46:14.850",10,800,"com.caucho.server.host.Host",
            "Host[] starting"
"2003-11-17 14:46:15.100",10,800,"com.caucho.server.webapp.Application",
            "Application[http://localhost:8080/freelistbm] starting"

Log Handlers

Resin provides a number of predefined custom log handlers for common logging patterns, including sending messages to JMS, HMTP, and the syslog service. Creating your own custom handler is also straightforward.

EventHandler, uri='event:'

The event handler publishes a LogEvent to the WebBeans event system. Any WebBeans component with an @Observes method for LogEvent will receive the notifications. The log handler classname is com.caucho.log.handler.EventHandler and the shortcut is uri="event:".

Example: event handler configuration
<web-app xmlns="http://caucho.com/ns/resin">

  <log-handler name="com.foo" level="warning" uri="event:"/>

</web-app>

HmtpHandler, uri='hmtp:'

The HMTP handler publishes the log message to a HMTP agent. The agent can be a custom HMTP service to process log messages. The HmtpHandler needs a JID (Jabber id) as the address of the target service.

Example: HMTP handler configuration
<web-app xmlns="http://caucho.com/ns/resin">

  <log-handler name="com.foo" level="warning" uri="hmtp:">
    <init>
       <to>test@localhost</to>
   </init>
  </log-handler>

</web-app>

JmsHandler, uri='jms:'

The JMS handler publishes the log message to a JMS queue.

Example: JMS handler configuration
<web-app xmlns="http://caucho.com/ns/resin">

  <jms-queue name="myQueue" uri="memory:"/>

  <log-handler name="com.foo" level="warning" uri="jms:">
    <init>
       <target>${myQueue}</target>
   </init>
  </log-handler>

</web-app>

SyslogHandler, uri='syslog:'

On Unix systems, the SyslogHandler lets you log messages to syslog.

Example: syslog configuration
<resin xmlns="http://caucho.com/ns/resin">

<log-handler name="" level="warning" uri="syslog:">
    <init>
      <facility>daemon</facility>
      <severity>notice</severity>
    </init>
</log-handler>

The possible values for facility are user, mail, daemon, auth, lpr, news, uucp, cron, authpriv, ftp, local0, local1, local2, local3, local4, local5, local6, local7. The default is daemon.

The possible values for severity are emerg, alert, crit, err, warning, notice, info, debug. The default is info.

See also `man 3 syslog' and `man syslog.conf'.

custom handler

Example: custom formatter configuration
<web-app xmlns="http://caucho.com/ns/resin">

  <log-handler name="" level="warning" class="demo.MyHandler"/>
  
</web-app>
Example: MyHandler.java
package demo;

import java.util.logging.*;

public class MyHandler extends Handler
{
  @Override
  public void publish(LogRecord record)
  {
    System.out.println(getFormatter().format(record));
  }
  
  @Override
  public void flush();
  {
  }
  
  @Override
  public void close();
  {
  }
}

Log Formatting

Sites may wish to change the formatting of log messages to gather information more appropriate for the site. The formatter can be custom-configured just like the handlers.

custom handler

Example: custom formatter configuration
<web-app xmlns="http://caucho.com/ns/resin">

  <log-handler name="com.foo" level="warning" path="WEB-INF/log.log">
    <formatter class="qa.MyFormatter"/>
  </log-handler>
  
</web-app>
Example: MyFormatter.java
package demo;

import java.util.logging.*;

public class MyFormatter extends Formatter
{
  @Override
  public String format(LogRecord record)
  {
    return "[" + record.getLevel() + "] " + record.getMessage();
  }
}

Standard Output Redirection

stdout-log

child of resin, server, host-default, web-app-default, web-app
default use the JDK's destination for System.out

Configure the destination for System.out.

Usage of the stdout-log overrides a previous usage. For example, specifying stdout-log as a child of a web-app causes a redirection of System.out for that web application only, and will override the System.out location in the enclosing host.

Warning The path must not be the same as the path specified on the command line with -stdout. If it is, there will be conflicts with which process owns the file.
archive-formatthe format for the archive filename when a rollover occurs, see Rollovers. see below
pathOutput path for the stream, see "Log Paths".required
path-formatSelects a format for generating path names. The syntax is the same as for archive-formatoptional
rollover-countmaximum number of rollover files before the oldest ones get overwritten. See Rollovers. none
rollover-periodhow often to rollover the log. Specify in days (15D), weeks (2W), months (1M), or hours (1h). See Rollovers. none
rollover-sizemaximum size of the file before a rollover occurs, in bytes (50000), kb (128kb), or megabytes (10mb). See Rollovers. 1mb
timestampa timestamp format string to use at the beginning of each log line.no timestamp

The default archive format is

path + ".%Y%m%d" or
  path + ".%Y%m%d.%H" if rollover-period < 1 day.

The following example configures System.out for a host. Unless a web-app overrides with it's own stdout-log, all web-apps in the host will write to the same output file.

...
<host id='foo.com'>
  <stdout-log path='/var/log/foo/stdout.log'
              rollover-period='1W'/>
  ...
</host>
...
  

stderr-log

child of resin, server, host-default, web-app-default, web-app
default use the JDK's destination for System.err

Configure the destination for System.err.

Usage of the stderr-log overrides a previous usage. For example, specifying stderr-log as a child of a web-app causes a redirection of System.err for that web application only, and will override the System.err location in the enclosing host.

Warning The path must not be the same as the path specified on the command line with -stderr. If it is, there will be conflicts with which process owns the file.
path Output path for the stream, see "Log Paths". required
path-formatSelects a format for generating path names. The syntax is the same as for archive-formatoptional
timestamp a timestamp format string to use at the beginning of each log line. no timestamp
rollover-count maximum number of rollover files before the oldest ones get overwritten. See Rollovers. none
rollover-period how often to rollover the log. Specify in days (15D), weeks (2W), months (1M), or hours (1h). See Rollovers. none
rollover-size maximum size of the file before a rollover occurs, in bytes (50000), kb (128kb), or megabytes (10mb). See Rollovers. 1mb
archive-format the format for the archive filename when a rollover occurs, see Rollovers. see below

The default archive format is

path + ".%Y%m%d" or
  path + ".%Y%m%d.%H" if rollover-period < 1 day.

The following example configures System.err for a host. Unless a web-app overrides with it's own stderr-log, all web-apps in the host will write to the same output file.

...
<host id='foo.com'>
  <stderr-log path='/var/log/foo/stderr.log'
              rollover-period='1W'/>
  ...
</host>
...

Access logging

child of server, host-default, host, web-app-default, web-app

Specify the access log file.

As a child of web-app, overrides the definition in the host that the web-app is deployed in. As a child of host, overrides the definition in the server that the host is in.

pathOutput path for the log entries, see "Log Paths". required
path-formatSelects a format for generating path names. The syntax is the same as for archive-formatoptional
format Access log format. see below
rollover-count maximum number of rollover files before the oldest ones get overwritten. See Rollovers. none
rollover-period how often to rollover the log. Specify in days (15D), weeks (2W), months (1M), or hours (1h). See Rollovers. none
rollover-size maximum size of the file before a rollover occurs, in bytes (50000), kb (128kb), or megabytes (10mb). See Rollovers. 1mb
archive-format the format for the archive filename when a rollover occurs, see Rollovers. see below
auto-flush true to flush the memory buffer with each request false
resin:type a class extending for custom logging com.caucho.server.log.AccessLog
initbean-style initialization for the custom classn/a

The default archive format is

path + ".%Y%m%d" or
  path + ".%Y%m%d.%H" if rollover-period < 1 day.
...
<host id=''>
  <access-log path='log/access.log'>
    <rollover-period>2W</rollover-period>
  </access-log>
  ...
</host>
...

The access log formatting variables follow the Apache variables:

%bresult content length
%Dtime taken to complete the request in microseconds (since 3.0.16)
%hremote IP addr
%{xxx}irequest header xxx
%{xxx}oresponse header xxx
%{xxx}ccookie value xxx
%nrequest attribute
%rrequest URL
%sstatus code
%{xxx}trequest date with optional time format string.
%Ttime taken to complete the request in seconds
%uremote user
%Urequest URI

The default format is:

"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\""

resin:type allows for custom logging. Applications can extend a custom class from . Bean-style initialization can be used to set bean parameters in the custom class.

...
<host id='foo.com'>
  <access-log resin:type='test.MyLog'>
             path='$server-root/foo/error.log'
             rollover-period='1W'>
    <init>
      <foo>bar</foo>
    </init>
  </access-log>
  ...
</host>
...

Log Paths

path is used to configure a destination for the messages. Typically, access-log, stdout-log, and stderr-log are configured to go to files, and log is configured to go to a file or to stderr or stdout so that they show up on the console screen.

PATHRESULT
filesystem pathoutput log entries to a file
stdout:output log entries to stdout
stderr:output log entries to stderr
Log messages to stdout
  <log name="" level="all" path="stdout:"/>

You can use the Environment EL variables as part of your filesystem path:

Filesystem path using Environment EL variables
  <log name="" level="all" 
       path="log/debug-${server.id}.log"
       rollover-period="1h" rollover-count="1"/>

Rollovers

Log rollovers are a way to stop your log files from getting too large. When a rollover is triggered, the existing log file is renamed and a new file is started.

Size based rollover

A size based rollover is triggered when the size of the file reaches a certain amount. The default Resin behaviour for log's is to rollover when the file size reaches 1mb.

rollover-size is used to specify the maximum size, and can be in bytes (50000), kilobytes (128kb), or megabytes (10mb). A value of -1 disables size based rollovers.

Time based rollover

A time based rollover is triggered when a certain period of time has passed since the last rollover. The default Resin behaviour is to perform no time based rollover, unless rollover-size has been disabled with a value of -1 in which case the default time period is 1 month.

rollover-period is used to specify the time period, and can be in days (15D), weeks (2W), months (1M), or hours (1h).

Archive files

When a rollover is triggered, the log file is renamed (archived) and a new log file is started.

archive-format is used to specify the name of the archive file. It can contain regular characters, EL Environment variables, and % codes that capture the current date and time. The % codes are the same as the ones used for timestamp (see Timestamp format string).

The default behaviour depends on the value of rollover-period. If rollover-period is greater than one day, or is not being used because rollover-size has been specified, the archive filename is the original path with .%Y%m%d appended. If rollover-period is less than one day, the archive filename is the original path with .%Y%m%d.%H appended.

Disabling rollovers

To completely disable rollovers, set the rollover-size to such a high number that it will never occur:

disable log rollovers
  <stdout-log path="log//stdout.log" rollover-size="1024mb"/>

Compression

Rollover log files can be compressed with gzip or zip. The extension of the archive-format determines the compression.

<log name="" level="warning" path='log/error.log'
     archive-format="%Y-%m-%d.error.log.gz"
     rollover-period="1D"/>

<access-log path="log/access.log"
            archive-format="access-%Y%m%d.log.gz"
            rollover-period="1D"/>

Timestamp format string

The timestamp for log tags is a format string which can contain percent codes which are substituted with time and date values.

CODEMEANING
%aday of week (short)
%Aday of week (verbose)
%bday of month (short)
%Bday of month (verbose)
%cJava locale date
%dday of month (two-digit)
%H24-hour (two-digit)
%I12-hour (two-digit)
%jday of year (three-digit)
%mmonth (two-digit)
%Mminutes
%pam/pm
%Sseconds
%smilliseconds
%Wweek in year (three-digit)
%wday of week (one-digit)
%yyear (two-digit)
%Yyear (four-digit)
%Ztime zone (name)
%ztime zone (+/-0800)
typical timestamp for the log tag
    <log name='' level='all' path='stderr:' timestamp="[%H:%M:%S.%s]"/>
[22:50:11.648] Application[/doc] starting
[22:50:11.698] http listening to *:8080
[22:50:11.828] hmux listening to *:6802

Copyright © 1998-2012 Caucho Technology, Inc. All rights reserved. Resin ® is a registered trademark. Quercustm, and Hessiantm are trademarks of Caucho Technology.

Cloud-optimized Resin Server is a Java EE certified Java Application Server, and Web Server, and Distributed Cache Server (Memcached).
Leading companies worldwide with demand for reliability and high performance web applications including SalesForce.com, CNET, DZone and many more are powered by Resin.

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