Exposing log service/func to be used by nodes and edges listeners

Camunda 7 Topics Discussion & Questions
1

Hey

What would be the best approach to expose a service / function for nodes and edges to perform logging via listeners?

I’d like to be able to put an expression such ${log('hello')} on nodes listeners and edges which will call some method that will just perform the logging via slf4j,

I’m using the standard Tomcat bundle,

Thanks.

2

Hi @Asaf_Shakarzy,

maybe you could just add this log level to your configuration:

name="org.camunda.bpm.engine.bpmn.behavior" level="debug"

Hope this helps,

Ingo

3

I want to have my own logs that are more business rather dump technical transitions details

4

Hi @Asaf_Shakarzy,

if you have Spring in your setup, you can add a Bean (https://docs.camunda.org/manual/7.9/user-guide/process-engine/expression-language/#external-context-variables-with-spring-and-cdi) to log and use this in listeners. (https://docs.camunda.org/manual/7.9/user-guide/process-engine/delegation-code/#execution-listener)

Hope this helps,

Ingo

5

@Ingo_Richtsmeier

yea i came across Spring but I guess the standard bundle comes without Spring setup and I was finding it too complicated to setup just for a single log bean.

I this or CDI are the only ways to expose a bean?

Thanks

6

They are the easiest one. You can find a configuration for spring in a shared engine in the getting started guide: https://docs.camunda.org/get-started/spring/shared-process-engine/. Have a look into the other chapters to understand, what’s going on in the project.

A more theoretical option is to configure the expressionManager in the engine to the org.camunda.bpm.engine.test.mock.MockExpressionManager. Then you can use Mocks.register(key, value) to add certain values (or classes). But this is invented for unit tests and not for production environment.

Cheers, Ingo

7

Pity there’s no simple way to bind a function to the EL resolver,

Alright then :slight_smile:, thanks a lot Ingo !

8

for those who’s seeking such solution,

I found an easy way (without going through dependency injection magics) that works both for nodes & edges by using a Java Class listener that performs the Logging while messages are set by field injection.

9

Take a look at this: https://github.com/DigitalState/camunda-coverage-generation-groovy/blob/master/src/main/groovy/io/digitalstate/camunda/coverage/bpmn/SequenceFlowHistory.groovy

And

You can covert the js into a java delegate if you wanted and just add the delegate to each sequence flow as a listener