On 18 Dec 2004, at 23:07, Scott Deboy wrote:
Enter and exit should not be defined as severities. This is useful information, but orthogonal to a logging event's severity attribute.
Good point. I think this would be an excellent distinction for a logging implementation (e.g. Log4J to make). Until such a distinction is already implemented in an existing logging framework, I don't think JCL has any business doing work (i.e. - implementations! bad!) in this area.
One way to provide entry/exit information is to overload the logger methods to take a map, and require the user to adhere to use-case specific conventions for keys and values.
For example, to track entry and exit as we cross component boundaries, these entries might be sufficient to identify an event:
Key Name Value ------------------------- boundary.type component boundary.state entry
Similarly, to track entry and exit as we cross class boundaries:
Key Name Value ------------------------- boundary.type class boundary.state exit
This provides a general mechanism for extending what information an event provides - without codifying use-case specific attributes as methods in commons-logging.
Again, the user would be responsible for conforming to naming conventions for the map entries (possibly with the aid of helper methods to build the map) in order to discover these use-case specific events.
Again, something a logging implementation may decide is appropriate, but something I don't think sould be in JCL.
interesting :)
this is a classic component design dilemma: more specific, strongly contracted methods or fewer, more generic ones. i'm not really convinced either way as yet. JCL has benefitted from a compact, strongly contracted API and it would be good to keep it that way.
IIRC ceki (in the past) convinced me (and probably a lot of others too) that there really isn't very much use in a plethura of logging levels. applications shouldn't really need anything much lower than debug. even for components, trace is more than a little debatable (though we went for it). a load of severities may look good in a policy document but are much less useful in practice and their usage patterns do not really generalize well. so, i don't really see the need for any more severities in JCL.
+1, I agree with you and Ceki. TRACE is debatable (I personally like it), more than TRACE is silly.
richard's proposal to add symantic methods (rather than severities) is therefore interesting. exit and entry tracing is common. at the moment, this works rather poorly when JCP is used with log4j: most people log these at trace which is mapped to debug by the bridge. unfortunately, this has the effect of making debug level almost unusable. separate, symantically meaningful methods would have the advantage that the bridge will know enough to make better choices.
-0. This is moving JCL out of the realm of bridging logging APIs and into the realm of providing logging implementations. For Log4J, enter/exit methods will end up being mapped to Log4J's DEBUG level. This means that JCL will have to provide the implementation that converts the enter/exit calls into DEBUG calls with a specific format. What format should be used? Are we going to force one on users of Log4J or make it configurable? And if it's configurable, that stinks of JCL becoming a logging *implementation* rather than *bridge*. Yuck! If I was a committer (you're probably glad I'm not!) I would probably -1 the enter/exit methods.
(so, i'm a little unsure about this issue at the moment.)
- robert
Matt
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