Let's say you have created a REST service named myService that will route requests to http://www.freekb.net. The Set Context Variable assertion can be used to create a variable. In this example, the "foo" variable will contain a value of "bar".

The Add Audit Details assertion can be used to append an event to the log which will show that the "foo" variable contains a value of "bar".

When a request is submitted into the API Gateway for the service, the audit log should contain the event.