With the Log Adapter you can write log messages to the standard or transaction log of an xUML service. To write these log messages, you can use

If you want to see an implementation for both, you can have a look at the following example:

Custom Logging

Runtime 2020.8 As of the mentioned xUML Runtime version, an updated logger implementation is available that follows the channel and sinks concepts.

You can define your own custom channel and sinks to log to. How to model this with the Builder is explained on Defining a Custom Logger Configuration.
For more information on the new logger concept, refer to xUML Runtime Logger Configuration.