RE: [smila-dev] RE: Current Logging Settings

[Thomas Menzel <tmenzel@xxxxxxx>]

hi daniel,

thx for ur input but i have some remark to:

/////////////
*  log exceptions before throwing new exceptions, e.g. 

...
if( paramXY == null ) {
    if (_log.isErrorEnabled()) {
        _log.error("paramXY is not set");
    }
    throw new NullPointerException("paramXY is not set");
}
////


I advise against this as it only causes the same message to be repeated at least twice, namely when the exception is created and then when the exception is logged itself.
IMO it is sufficient to have a verbose error msg and this then is reported along with the stack trace when the exception is logged.
if the exception is handled then this message is even confusing b/c u have ERROR log entry but wonder: what happened then?
if u deem the condition so extraordinary and dangerous we could log it as warning, but since we don’t log the eception here it should not be level ERROR.

even worse than this is sometimes the habit to log an exception before (re)throwing or wrapping it, which I have seen as often (in general, not this project in particular).
this then has the effect that u have the same exception logged several times which makes the log very verbose and confusing. as u think u have lot of problems/exception when it fact it is only that one case.

of course this only applies when u remain within our own system bounds. if u write a libray that is called from other code then it is wise to log the exception at ur system boundery, i.e. the method that was called by the client, that might not adhere to sound loging standards.
again, there are also pitfalls with this convention, e.g. in case of an overloaded API method where u have a simple version that delegates to a more verbose other API method that also could be called from a client.

Kind regards
Thomas Menzel @ brox IT-Solutions GmbH


-----Original Message-----
From: smila-dev-bounces@xxxxxxxxxxx [mailto:smila-dev-bounces@xxxxxxxxxxx] On Behalf Of Daniel.Stucky@xxxxxxxxxxx
Sent: Montag, 29. September 2008 14:36
To: smila-dev@xxxxxxxxxxx
Subject: AW: [smila-dev] RE: Current Logging Settings

Hi all,

I added a section "Logging guidelines" to our Development_Guidelines:
http://wiki.eclipse.org/SMILA/Development_Guidelines#Logging_guidelines
Feel free to comment or improve.

I ask all to share their thoughts about how to fill the table "When to use what log level and what information to provide?" 
Especially those who have trouble finding the "real" errors :-)

Bye,
Daniel