Ceki usually is pretty responsive but I haven't seen him post for a
few days. I'm guessing he must be taking a few days off.
On Sep 9, 2009, at 7:04 PM, david_z wrote:
Hi,
I'm new to logback and am in the process of evaluating as a
replacement for
log4j. A question was raised today at work regarding parameterized
logging
and the ability to modify logback to support java.text.MessageFormat
style
formatting in order to, for example, perform date or currency
formatting:
log.debug("myDate={0,date,MMM d}", myDate);
log.debug("myAmount={0,number,currency}", myAmount);
or to defer array formatting, similar to the question I'm replying
to above.
I appreciate the performance reasons for logback using {}
replacement, but
it seems like it should be possible to allow the user to provide an
alternate formatting strategy if they so desire without negatively
impacting
the default's performance. Creating my own MessageConverter, as
suggested
above, to perform this formatting works fine, except the conversion is
performed once per appender per event rather than just once per event.
Is there a better way to handle this custom formatting goal?
Actually, the MessageConverter doesn't do anything. All it does is
retrieve the message as it was formatted by SLF4J. If you want to do
formatting then create your own layout and/or converter.
If not, I have a suggestion for an enhancement.
1. Add a Formatter interface with the method
String format(String messagePattern, Object[] argArray)
Converters implement String convert(ILoggingEvent event). If you look
at how the pattern layout works, the parameters for the individual
converters are passed to them.
2. The LoggingEvent would need access to the formatter. Ideally the
Formatter could be configured via the config file as the Converters
can be.
I don't know enough about the source to flesh this part out well.
It works the other way around. The Converters have access to the
logging event.
3. Modify getFormattedMessage() in the ILoggingEvent implementations
public String getFormattedMessage() {
if (formattedMessage != null) {
return formattedMessage;
}
if (argumentArray != null) {
if (formatter == null) {
formattedMessage = MessageFormatter.arrayFormat(message,
argumentArray);
} else {
formattedMessage = formatter.format(message, argumentArray);
}
} else {
formattedMessage = message;
}
return formattedMessage;
}
What do you think?
1. I think Logback already provides a mechanism to do what you want.
2. I've been working on an enhancement to SLF4J and logback to
support RFC 5424, the new IETF syslog specification. (See http://tools.ietf.org/html/rfc5424
). In particular, the concept of Structured Data. You can play with
what I have so far by checking it out from git://github.com/rgoers/slf4j.git
and git://github.com/rgoers/logback.git. However, your idea of
associating a converter with specific keys isn't something I had
thought of but is worth considering, however I'd probably want to
provide the definitions in the configuration, not in the actual logger
calls. So far I've just focused on implementing something that adheres
to the specification but I'd be interested in suggestions on how to
improve it.
Ralph
Ralph
_______________________________________________
Logback-user mailing list
[email protected]
http://qos.ch/mailman/listinfo/logback-user
