Logs and Logging

Log file is a file that records either events that occur when applications are run or messages sent between different computer systems and tools.

Log files are generally used for testing, debugging, and troubleshooting.

There are several groups of logs created by different Lycia components:

• Error logs;
• Application logs;
• Web server logs.

By default = immediately after you have installed Lycia:

• Error logging is fully controlled by a 4GL developer;
• Web server logging is switched on.

Error Logs

Error logs (also called startlogs) are log files initialized by the 4GL developer from a 4GL application.

Error logs store error messages obtained when your 4GL applications are run.

Error logs are created by startlog() - the function that initializes error logging and opens the error log file:

CALL startlog("new_program")

CALL startlog("new_program.txt")

CALL startlog("C:\my_work\my_logs\new_program.txt")

If the path you specified for storing error logs doesn't exist, Lycia will create it automatically.

If you do not specify the path, error log will be stored in the same folder as the executable file of the program, in which the error log is initialized.

Error logs get their entries by errorlog(). This means that error logs can include not only error messages but also user messages added by the 4GL developer to the 4GL code by errorlog().

Details of the error message depend on what object_cache is used - release or debug.

With release cache, line info is usually excluded:

With debug cache, line info is included:

If necessary, you can switch on the line info for release cache by setting the QX_REL_LINE_INFO environment variable before building the object_cache:

QX_REL_LINE_INFO=1

Error messages written to error logs also depend on the WHENEVER statement. For example, with WHENEVER ANY ERROR CONTINUE, errors will be skipped, and runtime and error messages will not be written to error logs.

Error logs are appended after every application launch:

You can also write to the error logs file using errorlog():

CALL errorlog("Unexpected error encountered")

or

CALL errorlog(err_get(-999))

 

 

Application Logs

Application logs (also called qrun logs or runtime logs) are logs initialized at the moment of application launch.

Application logging is initialized (and a log file is created) every time you run the application.

Application log files are located in the folder specified in listener.xml by the tag <logdir>...</logdir>. By default, it is:

The name of the application log files includes the application name and the timestamp:

<application_name>.<timestamp>.log

For example,

test.exe.2017-12-28_21.36.30.814.log

The content of an application log file is determined by these environment variables:

QXDEBUG

QX_REL_LINE_INFO

LYCIA_SEVERITY

QX_TRACE

QX_TRACE_ARG_DUMP

LYCIA_POST_MORTEM_LENGTH

 

If the inet.env configuration file is not generated, you should create it and set the QXDEBUG environment variable set to QXDEBUG=mv.

If you do not change the inet.env, then your application log will include:

• the process environment - consists of the system environment and runtime environment;
• process ID;
• number and the arguments of the applications (application name is one of these arguments);
• error messages, if any.

By setting environment variables, you can make application logs more detailed:

QXDEBUG	logs the debugging results, for example: object_cache info; errors and warning states; SQL issues and errors; messages passing between client and server, etc.
QX_REL_LINE_INFO	switches on line info for release cache
LYCIA_SEVERITY	specifies the logging level for the application. Allow logging: runtime errors; potentially harmful runtime situations; operations that occur on a non-recurrent basis; all the steps performed by the application.
QX_TRACE	enables tracing of function calls for user-defined functions
QX_TRACE_ARG_DUMP	enables tracing of both function calls for user-defined functions and their arguments
LYCIA_POST_MORTEM_LENGTH	specifies how many last log messages are written to the application log file when an application crashes

To include object_cache information to the application logs, you must set these environment variables and their values to inet.env:

QXDEBUG=PzVzT

LYCIA_SEVERITY=TRACE

QX_TRACE=1

QX_TRACE_ARG_DUMP=1

 

 

Web Server Logs

Web server logs are log files that log the operation of the application server (Jetty).

Web server logging is initialized when Querix Lycia Web Application Server is started.

Web server log files are located in the Jetty logs folder:

In its default configuration, Lycia Web Server:

commons-daemon.<date>.log	logs the start of the Querix Lycia Web Application Server
qxweb_7-stderr.<date>.log	captures and logs all STDERR output
qxweb_7-stdout.<date>.log	captures and logs all STDOUT output

Here is an example of commons-daemon.<date>.log file: