How to log to catalina.out from a javascript Listener

Camunda 7 Topics Discussion & Questions
1

Hello all

I’m trying to print to catalina.out from a javascript Listener, but fail to figure out how to achieve that.
I’m using v7.9 CE with the embedded Tomcat server.

Can this be done?
Thanks so much

2

Hi @eugene,

Do you already know how you would do that from Java code?

Cheers,
Thorben

3

Hello @thorben

I spent many hours trying to figure out the correct syntax for println().
I hope this will help someone else from having to do the same.
During my searching I also came across the following methods:

1 print(“Hello”);
2 java.lang.System.out.println(‘Hello’); //must be ’ and not "
3 var logger = java.util.logging.Logger;
var log = logger.getLogger(‘MY_JS_LOGGER’);
log.info(‘Hello’);

Option 3 is not causing an error but nothing appears in catalina.out either.

Thanks for your response.

4

Did you try with the proper nashorn syntax for accessing java classes ? https://wiki.openjdk.java.net/display/Nashorn/Nashorn+extensions

5

Thanks @StephenOTT

As always, your assistance is much appreciated.

6

Also note that Js is not cached in Camunda executions. So there will be extra overhead if you go with your option 3. If you really need it, I would look at something like creating a engine plugin that generates a static logger for you to access rather than generating new loggers every execution of a script. Again only if you are using option 3.

For option 2 you can see a example here: https://docs.camunda.org/manual/7.9/user-guide/process-engine/scripting/#printing-to-console-using-scripts

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