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. 

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.

Whenever the APL function log.* is called in the Analysis agent, this function invokes logging with log4j. After the workflow is done executing with a specific EC, a new EC specific configuration file <ec-name>-apl-log4j.properties will be created. This new EC specific configuration file is created by default with the same configurations saved in the file apl-log4j.properties. For instance, if the EC name is ec1 then ec1-apl-log4j.propertiesis created in $MZ_HOME/etc/logging and will have identical settings as apl-log4j.properties.

MZSH does not support dedicated commands to make changes to the log level. Changes on the log level and other properties in the configuration file must be made manually. Whatever changes made to the configuration file takes effect at the next workflow run without the need to restart the EC.

In a multi-host installation, the EC specific configuration file is always created on the host where EC is located. Therefore, log4j always read the EC specific configuration according to the EC location. For instance, workflow run by ec1 located on host my-host-name. The log4j always read the EC specific configuration file ec1-apl-log4j.properties located at path $MZ_HOME/etc/logging on host my-host-name.

The content of the files defines the logging.

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.

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.