Logging in FESA


In FESA a selection of diffent loggers is available. Each C++ class has its own logger. All loggers are identified by their name which is usually identical with the C++ class name.

In order to be able to filter and redirect the different log-messages in a proper way, the prefix of the names of the loggers is standardized:
  • General Logging ( granularity can be controlled during startup only)
    • FESA.FWK : logged by the framework ( fesa-core, fesa-core-gsi )
    • FESA.USR : logged by the FESA class developer
  • Diagnostic Logging ( granularity can be controlled at runtime)
    • FESA.DIAG.FWK : All informational messages which fit into one of the diag-fwk-topics, logged by the FESA framework
    • FESA.DIAG.USR : All informational messages which fit into one of the diag-custom-topics, logged by the FESA class developer
In FESA there are three predefined appenders for log messages: The console (std::out), syslog and cmw-log-stomp (udp).

As of Release 7.0.0, the syslog appender has been replaced with the GELF appender that logs directly to Graylog. Syslog is still available by editing log.cfg.

The following diagram shows the default message routing:


If required, it is possible to reconfigure the message routing in the file "log.cfg". Which log.cfg to use can be passed to a FESA binary as application argument during start. You can find the standard logging configuration file at: "/opt/fesa/fesa-core-gsi/[FESA-Version]/log.cfg". To change the log level for FESA.USR log messages adapt the parameter
# Standard-Logging for class-developers. Per default logs WARNING and all above
logger.FESA.USR.level = WARNING

in a custom copy of the standard logging configuration file. To use the custom logging configuration file use the application argument -cfglog <path to custom log configuration file>.

For more detailed information on how to configure logging via the logging configuration file please refer to the services group.

Per default the FESA Loggers FESA.FWK and FESA.USR only log warnings and errors. The verbosity can be configured either in the file log.cfg, or by passing application arguments to FESA:
  • -v : verbose, log everything with the level "debug" and higher
  • -vv : very verbose, log everything with the level "trace" and higher

Here is a complete list of the middleware log levels:
  • LL_AUDIT = 60, ///< A special level that can be used to turn off all logging, apart from audit logs.
  • LL_ERROR = 50, ///< A message level indicating a serious problem.
  • LL_WARNING = 40, ///< A message level indicating a potential problem.
  • LL_INFO = 30, ///< A message level for information messages.
  • LL_DEBUG = 20, ///< A message level providing debugging information.
  • LL_TRACE = 10 ///< A message level providing highly detailed tracing information.

Information to the infrastructure of logging can be found here: https://www-acc.gsi.de/wiki/IN/DiagnosticLogging

General Logging

  • Should be used by class developers in order to log errors and warnings
  • Is enabled by default for errors and warnings
  • Since as well all FESA-FWK internal logs use the general logging, it is recommended to not use the general logging for LOG_TRACE, etc. ( your log viewer will be flooded by FESA FWK log messages )

Here a code snippet which can be used everywhere in the code of a FESA class:
std::ostringstream message; 
message << "Place your log message here" ; 
LOG_ERROR_IF(logger, message.str()); 
// Depending on the level of your log message you can use of the following macros:
// LOG_TRACE_IF(logger, message.str());  // In FESA classes you should use the diagnostic-logging instead 
// LOG_DEBUG_IF(logger, message.str());  // In FESA classes you should use the diagnostic-logging instead 
// LOG_INFO_IF(logger, message.str());   // In FESA classes you should use the diagnostic-logging instead 
// LOG_WARNING_IF(logger, message.str()); 
// LOG_ERROR_IF(logger, message.str());

Separate Framework and User Log Levels on SCU

Using the -v/-vv arguments will show both User and Framework messages. It is possible to select only user trace messages by changing log.cfg

logger.FESA.USR.level = TRACE
logger.FESA.USR.level = WARNING

Note that log.cfg wil be overwriten during a new deployment.

General Logging - Viewer: Graylog

For information on using Graylog to view log messages see:


General Logging - Viewer: Console

If the FESA binary is launched via the start script, all messages from the general logging will be displayed on the related console.

General Logging - stdout/stderr

If the FESA binary is launched via the manual start script, stdout and stderr will be shown on the console only.

If the FESA binary is launched via the daemon start script, stdout will not be shown and stderr will be redirected to graylog. Messages sent to logging via stderr are not guaranteed to arrive in one piece or in the correct order so avoid using stderr for production systems.

Diagnostic Logging´╗┐

  • Can be used by class developers in order to debug a running FESA class
  • Some framework topics can be used by default
  • FESA class specific topics can be added by the FESA class developer

Diagnostic Logging can be enabled by using the global property "DiagnosticSetting" e.g. via the FESA Explorer. In the FESA Explorer it is possible to define which log traces are shown on the console and in the Trace View. In order to use FESA class specific Diagnostic Logging, you have to add class-specific "log-topics" to your FESA class design. ( FESA framework topics can be viewed by default). This can be done by extending the existing custom-type "diag-custom-topic" E.g:
      <diag-custom-topic name="DIAG_TOPIC">
         <b0 name="StartupPowerSupply" />
         <b1 name="Ramping" />
         <b2 name="ShutdownPowerSupply" />
         <b3 name="MY_DIAG_TOPIC" />

In your code you can now make use of the defined topics like that:

// Via the DiagnosticProperty, messages of specific devices can be enabled/disabled
// So if a message is device specific, the following Makro should be used: 

Diagnostic Logging - Viewer: FESA Explorer

During runtime of the FESA binary it is possible to enable / disable each log topic in the FESA Explorer:

Logging in the FEX1

All messages for the specified topic filter can now be observed

Logging in the FEX2

Diagnostic Logging - Viewer: Console

If the FESA binary is launched via start script, all messages from enabled diagnostic-channels will be displayed on the related console.

Logging in CMW

Logging is also performed independently of FESA by the CMW middleware, recording RDA sets and optionally gets and subscriptions.

The log level can be set in log.cfg, the default is "logger.cmw.level=WARNING".

What is logged by cmw-rda3-cpp by loglevel

Log Level Logged
Audit (60) RDA-SET
Info (30)




Contents of CMW log messages

CMW log messages show the client connection and request context information:

RDA-SET device="DEVICENAME" property="PropertyName" client="user@host/pid" applicationId="app=appname;uid=user;host=hostname;pid=processid;" framework="RDA3" context="RequestContextImpl[selector=; filters=; data=]"

The contents of the RDA data container are not shown.
Topic attachments
I Attachment Action Size Date Who Comment
FEX_Logging1.pngpng FEX_Logging1.png manage 32 K 15 Jan 2015 - 13:35 AlexanderSchwinn  
FEX_Logging2.pngpng FEX_Logging2.png manage 36 K 15 Jan 2015 - 13:36 AlexanderSchwinn  
Overview.jpgjpg Overview.jpg manage 37 K 26 Feb 2016 - 14:15 AlexanderSchwinn  
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Topic revision: r15 - 02 Apr 2020, DominicDay
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