Some requests may go through numerous systems. For example, a request may be submitted to a web server, and then the web server forwards the request onto an application server, and then the application server may need to query data from a database. Cross Component Tracing (XCT) allows you to correlate requests that traverse through multiple systems. 

Cross Component Tracing adds a unique request ID to SystemOut.log or trace.log. Let's consider an example where a request is passed from application server "a" to application server "b". With Cross Component Tracing enabled, there will be events in SystemOut.log or trace.log in both application servers that contain the same request ID. In this way, using the request ID, you can correlate the events between the SystemOut.log or trace.log as being part of the same request.

requestID=abcdefg123456 hello world

By default, Cross Component Tracing is not enabled, thus the first step is to enable Cross Component Tracing.

Since Cross Component Tracing adds the Request ID to SystemOut.log or trace.log, there is no new or unique log file used for Cross Component Tracing.