[Clockwork-developers] Logging

[Joel L. <jo...@lo...>]

Shawn McMahon and I had a conversation weeks ago about logging. Depending
on how our users do their monitoring, they may need our software to log to
any number of different formats/destinations.

Shawn came up with a pretty comprehensive list:
 * file
 * syslog
 * SNMP trap
 * Windows event log

That should satisfy just about everyone. I can't imagine anyone who's serious
about monitoring their hosts and applications not being able to pick up
error messages from at least one of those sources.

The user should be able to configure multiple logging destinations, and
set a minimum severity for each. For example, it should be possible to
configure logging like:
 + DEBUG or higher -> /var/log/clockwork.log
 + INFO or higher  -> syslog
 + WARNING or higher -> send as SNMP trap

Having different places to log, each with their own semantics for severity,
will require some abstraction so that Clockwork can log to a common logging
API, and that thing can figure out how to translate it to the API of
a particular backend. Luckily, the nice folks at Apache's Jakarta project
have already done just this with the Commons Logging component. It's described
as "an ultra-thin bridge between different logging libraries." They
have created the common logging API, and make it easy for you to write a little
code that plugs in whatever backend you want to use to their logging
framework.

Incidentally, they've already got the "plug-in" for Log4J written, which
handles file and syslog logging. So all that's left is SNMP traps and
Windows event log. I did a little digging, and I'm afraid there's no
way to do the Windows event log in pure Java -- a .DLL must be involved.

If you're interested in doing some reading, here are a couple of references:
http://jakarta.apache.org/commons/logging.html
http://jakarta.apache.org/log4j/index.html

-- 
Joel