Typical Types of Trace Messages 

Since trace messages are used for understanding the program execution path and the internal status of the application, two principal types of trace messages can be distinguished (the referenced methods belong to class com.sap.tc.logging.Location):

·        Program flow trace messages

Information about which part (subroutine/method) of the program is executed and what control flow action is performed (method entered or exited, normally or via exception) is needed. Especially if the program flow leaves one component and enters an other component (with other responsible development groups), trace messages must be issued to help support engineers in localization of the right responsible.

Messages of this type must use the severity level Path. The SAP Logging API provides helper methods like entering(), exiting(), throwing() and catching().

·        Program context trace messages

”Program context” can be:

Ў        Information about the semantically execution step (think of important business process functions like “Calculating the price for item XYZ”) and its results (“Price for item XYZ is EUR nn”).

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Messages of this type must use the severity level INFO.

Ў        Status of important variables. This has to be used with care to avoid replacing debugging completely. Usually these are variables holding a status description.

Messages of this type must use the severity level DEBUG.

Ў        Important return codes of calls (like accesses to external resources, resource bundles, processing engines, libraries etc.). Depending on the evaluation of the return code the severity level can be DEBUG or INFO.

Ў        Results of condition checks (assertions). If there are critical conditions, which need to be satisfied in specific places of the code (otherwise the processing has to be terminated), a trace message describing the failed condition must be issued. This can be used to check for non-repairable inconsistencies in the program status.

The severity level of such kind of messages must be ERROR. The SAP Logging API provides the helper method assertion().

Ў        Technical information in application termination conditions. Normally as part of the error handling an exception is created. A notification on this event has to be written as a log entry. If it is necessary to write additional technical context information (like variable values, etc.), this must be written as a trace with severity ERROR immediately before the throw statement (or inside a catch block).