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Writing to the Correct Log

Let's start with the basics first. In order to write into the log files correctly, we should make use of the LogUtil (Source code: https://github.com/jogetworkflow/jw-community/blob/6.0-SNAPSHOT/wflow-commons/src/main/java/org/joget/commons/util/LogUtil.java) utility class.

We should not use the following to print out log in writing our own plugins.

System.out.println("Execution is successful");

This is because this line of message would appear in catalina.out but not in the default Joget's log file, joget.log.

Instead, we should make use of these methods provided by LogUtil. Check out the some sample in the codes used by Email Tool (Source code: https://github.com/jogetworkflow/jw-community/blob/6.0-SNAPSHOT/wflow-core/src/main/java/org/joget/apps/app/lib/EmailTool.java#L227)

LogUtil.info(EmailTool.class.getName(), "EmailTool: Sending email from=" + email.getFromAddress().toString() + ", to=" + to + "cc=" + cc + ", bcc=" + bcc + ", subject=" + email.getSubject());
LogUtil.info(EmailTool.class.getName(), "EmailTool: Sending email completed for subject=" + email.getSubject());
LogUtil.error(EmailTool.class.getName(), ex, "");

Separate Logs of Different Origin/Plugins into Different Log Files

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Navigate to the "[JogetFolder]\apache-tomcat-8.5.23\webapps\jw\WEB-INF\classes\log4j.properties" configuration file and check out the use of R2 tag to see how EmailTool, UserNotificationAuditTrail, and ExportFormEmailTool are writing into email.log file. 

log4j.logger.org.joget.apps.app.lib.EmailTool=DEBUG, R2
log4j.logger.org.joget.apps.app.lib.UserNotificationAuditTrail=DEBUG, R2
log4j.logger.org.joget.plugin.enterprise.ExportFormEmailTool=DEBUG, R2

# A1 is set to be a ConsoleAppender.
log4j.appender.A1=org.apache.log4j.ConsoleAppender

# A1 uses PatternLayout.
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-5p %d{dd MMM yyyy HH:mm:ss} %c %x - %m%n

# R is set to be DailyRollingFileAppender
log4j.appender.R=org.apache.log4j.DailyRollingFileAppender
log4j.appender.R.File=${catalina.home}/logs/joget.log
log4j.appender.R.DatePattern='.'yyyyMMdd
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%-5p %d{dd MMM yyyy HH:mm:ss} %c %x - %m%n

# R2 is set to be DailyRollingFileAppender
log4j.appender.R2=org.apache.log4j.DailyRollingFileAppender
log4j.appender.R2.File=${catalina.home}/logs/email.log
log4j.appender.R2.DatePattern='.'yyyyMMdd
log4j.appender.R2.layout=org.apache.log4j.EnhancedPatternLayout
log4j.appender.R2.layout.ConversionPattern=%-5p %d{dd MMM yyyy HH:mm:ss} %-50c - %m%throwable{0}%n

Identifying App Origin in Log Files

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In the section above, we talked about using LogUtil to write into the log files and how to write into separate files too. When we have too many apps running in the same copy of Joget, sometimes it is trace certain line of messages to the origin of Joget apps that trigger them.

For example, let's look at these log messages.

ERROR 17 Jun 2019 17:29:39 org.joget.apps.app.lib.EmailTool  - org.apache.commons.mail.EmailException: Sending the email to the following server failed : smtp.outlook.comtest:587
org.apache.commons.mail.EmailException: Sending the email to the following server failed : smtp.outlook.comtest:587
	at org.apache.commons.mail.Email.sendMimeMessage(Email.java:1421)
	at org.apache.commons.mail.Email.send(Email.java:1448)
	at org.joget.apps.app.lib.EmailTool$1.run(EmailTool.java:239)
	at java.lang.Thread.run(Thread.java:748)
	at org.joget.commons.util.PluginThread.run(PluginThread.java:22)

There is no way that we can tell from which Joget app the EmailTool is triggered. However, in a Process Tool's execute method, we can obtain the appDef object which contains the Joget app information. Check out the sample code below.

public Object execute(Map properties) {
	
	AppDefinition appDef = (AppDefinition) properties.get("appDef");
	String appInfoAndMessage = appDef.toString() + "- Something happened";
	LogUtil.error(EmailTool.class.getName(), ex, appInfoAndMessage);
	
}

This way, we would be able to trace to the app that triggers and writes the line of message in the log file.

import org.joget.apps.app.service.AppUtil;

AppDefinition appDef = AppUtil.getCurrentAppDefinition();

Large catalina.out File

We can consider to LogRotate the log files. Please see the following links:-

•  https://dzone.com/articles/how-rotate-tomcat-catalinaout
• https://www.thegeekstuff.com/2010/07/logrotate-examples

As for joget.log, we are already using Log4J for rotation as seen in the log4j.properties file snippet above.