The system includes a log4j extension that enables generation of customized logs from agents configured with APL. This section describes how to configure these logs to meet deployment specific requirements.

Configuration Files

There is a configuration file called apl-log4j.properties containing default settings located in the $MZ_HOME/etc/logging directory that is used to specify the path of log files, log filtering rules, log level and formatting. If you want to use different settings for different Execution Contexts, this file can be copied and renamed to <ec-name>-apl-log4j.properties where you can configure different settings for the specified EC.

To provide some examples and templates, there are a number of pre-existing files with the name apl-log4j-<log level name>.properties, for example apl-log4j-trace.properties, which you can use to either copy properties from, or make a copy of the whole file and rename it to <ec-name>-apl-log4j.properties.

Example. Configuration filenames

Default configuration file:

$MZ_HOME/etc/logging/apl-log4j.properties

EC specific configuration file for ec1:

$MZ_HOME/etc/logging/ec1-apl-log4j.properties

Copying the default configuration file into an EC specific configuration file:

$cp apl-log4j.properties ec1-apl-log4j.properties

Copying a template configuration file into an EC specific configuration file:
$cp apl-log4j-trace.properties ec1-apl-log4j.properties

The following template configuration files are included by default:

apl-log4j-off.properties
apl-log4j-fatal.properties
apl-log4j-error.properties
apl-log4j-warn.properties
apl-log4j-info.properties
apl-log4j-debug.properties
apl-log4j-trace.properties
apl-log4j-all.properties

The files listed above have a different log level setting but are otherwise identical.

The content of the files defines the logging.

Example. Configuration file contents

log4j.logger.aplLogger=ALL, a
log4j.appender.a=com.digitalroute.apl.log.DRRollingFileAppender
log4j.appender.a.file=${mz.home}/log/{pico}_{workflow}.log
log4j.appender.a.layout=com.digitalroute.apl.log.JsonLayout
log4j.appender.a.layout.MdcFieldsToLog=pico, workflow, agent, tag

The first line in the example above sets the log level and declares an "appender" named 'a'. The available log levels are listed below in order of severity, from highest to lowest:

OFF
FATAL
ERROR
WARN
INFO
DEBUG
TRACE
ALL

Messages of the same or higher severity than the selected level are logged. For instance, if the configured log level is WARN, messages with the severity ERROR and FATAL will be logged as well. The other settings above mean that messages are logged in files that are started, stopped and stored in JSON formatted files in the $MZ_HOME/log directory in regular intervals. When an active log file has reached its maximum size, it is backed up and stored with a number suffix. A new active log file is then created. The default maximum size is 10 MB, and the default number of backup files is one (1).

Appenders

There are two different types of appenders; DRRollingFileAppender och DRRollingMultiFileAppender.

DRRollingFileAppender

Writes to a single defined file based on the log4j.appender.<appender name>.file property

DRRollingMultiFileAppender

Writes one file for each workflow instance it encounters based on the log4j.appender.<appender name>.file

Which workflows are written into which appender is based on the log4j.logger.<class name> property.

Examples Appender Configurations

# Default
log4j.appender.Default=com.digitalroute.apl.log.DRRollingFileAppender
log4j.appender.Default.file=${mz.home}/log/log4j/{workflow}.log
log4j.appender.Default.layout=org.apache.log4j.PatternLayout
log4j.appender.Default.layout.ConversionPattern=[%d{dd MMM yyyy HH:mm:ss,SSS}];[%-5p];[pico=%X{pico}];[%t];[tag=%X{tag}];[%c]:%m%n
log4j.appender.Default.MaxFileSize=10MB
log4j.appender.Default.MaxBackupIndex=20
log4j.logger.aplLogger.Default=TRACE, Default

The appender named Default will write a single file for all workflows contained under the Default folder.

# PRIMARY
log4j.appender.PRIMARY=com.digitalroute.apl.log.DRRollingMultiFileAppender
log4j.appender.PRIMARY.file=${mz.home}/log/log4j/{workflow}.log
log4j.appender.PRIMARY.layout=org.apache.log4j.PatternLayout
log4j.appender.PRIMARY.layout.ConversionPattern=[%d{dd MMM yyyy HH:mm:ss,SSS}];[%-5p];[pico=%X{pico}];[%t];[tag=%X{tag}];[%c]:%m%n
log4j.appender.PRIMARY.MaxFileSize=10MB
log4j.appender.PRIMARY.MaxBackupIndex=20
log4j.logger.aplLogger.RT_Folder.RT_TEST_WF=TRACE, PRIMARY

The appender named Primary will create multiple files; one for each workflow instance based on the RT_Folder.RT_TEST_WF workflow.

# SECONDARY
log4j.appender.SECONDARY=com.digitalroute.apl.log.DRRollingFileAppender
log4j.appender.SECONDARY.file=${mz.home}/log/log4j/{workflow}.log
log4j.appender.SECONDARY.layout=org.apache.log4j.PatternLayout
log4j.appender.SECONDARY.layout.ConversionPattern=[%d{dd MMM yyyy HH:mm:ss,SSS}];[%-5p];[pico=%X{pico}];[%t];[tag=%X{tag}];[%c]:%m%n
log4j.appender.SECONDARY.MaxFileSize=10MB
log4j.appender.SECONDARY.MaxBackupIndex=20
log4j.logger.aplLogger.RT_Folder.RT_TEST_WF=TRACE, SECONDARY

The appender Secondary will create a single file for each workflow instance based on the RT_Folder.RT_TEST_WF workflow. The file will take the name of the first workflow instance it encounters, for example "RT_Folder.RT_TEST_WF.workflow_1"

For more information about available settings, see the log4j documentation at https://logging.apache.org/log4j/1.2/manual.html.

APL Commands

The following functions are used to trigger logging within any of the function blocks in APL:

void log.fatal(any, any)
void log.error(any, any)
void log.warn(any, any)
void log.info(any, any)
void log.debug(any, any)
void log.trace(any, any)

For more information about these functions, see Log and Notification Functions.

Log Output

The output log files are stored in the directory specified in the active logging configuration.

The fields in the log output are described below.

Field	Description

Field	Description
timestamp	The time when the message was logged. The UTC timezone and international standard date and time notation is used by default. You can specify the date format by adding the following line in the configuration file: `log4j.appender.a.layout.DateFormat=<Java SimpleDateFormat pattern>` For information about how to use SimpleDateFormat patterns, see: https://docs.oracle.com/javase/8/docs/api/java/text/SimpleDateFormat.html
level	The log level i e `FATAL`, `ERROR`, `WARN`, `INFO`, `DEBUG`, or `TRACE`.
thread	The name of the workflow thread.
category	The logged configuration. This field contains the `category` class of the appender that is defined in the configuration file.
message	The log message is specified in the APL command.
pico	The name of the Execution Context.

MediationZone Documentation 9.2

log4j APL Logging Configurations