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The platform makes uses of slf4j logging using logback. Logging levels may either be configured using a logback.xml configuration, or using arguments such as

NPL logging uses the same logging mechanisms as the platform itself. NPL log statements are marked "NPL" using an slf4j marker. This makes it easy to treat NPL log statements differently from other log statements in the engine. The logger name for NPL log statements is always set to the name of the NPL element that performs the logging.

Refer to the Errors page for the list of NPL runtime errors.



A few predefined environment variables exist for commonly encountered use cases.

Note that ENGINE_LOG_CONFIG=classpath:/logback-json.xml will cause the engine to send the logs to standard output using the ECS Format.


The history application provides a few predefined environment variables for fine-tuning the logging behaviour.