[slf4j-user] basic MDC support for java.util.logging

[Ceki Gulcu]

Hi Maarteen,

Comments inline.

Maarten Bosteels wrote:
 > Hello Ceki,
 >
 > I started coding a BasicMDCAdapter that could be used by java.util.logging
 > Had a look at the log4j MDC implementation and also at LogbackMDCAdapter code.
 >
 > Currently my implementation is roughly the same as the LogbackMDCAdapter
 > without the generics (since SLF4J should run on 1.4 right ?)

Yes, SLF4J must run under JDK 1.4 or later.

 > I didn't quite understand this remark in the code:
 > * Each time a value is added, a new instance of the map is created. This is
 > * to be certain that the serialization process will operate on the updated map
 > * and not send a reference to the old map, thus not allowing the remote
 > logback
 > * component to see the latest changes.

That's an implementation detail in logback. You can safely ignore it
for JUL.

 > Can you describe a scenario where serialization would fail if one just add a 
value to the map ?
 > Is it a threading issue ?

No, it's not a threading issue. As mentioned previously, you can ignore the 
aforementioned comments in logback code.

[snip]

 > It would be cool if logback would also have an Log4jXmlLayout. I think the 
xml layout has several advantages over serialization:
 > * it's more compact (much to me surprise) certainly when combined with a 
GZipOutputStream
 > * human readable
 > * easier to implement in other languages (eg. log4cxx)
 > * no need to depend on log4j's LoggingEvent
 > * protected against changes to the serialized form of log4j's LoggingEvent
 > for example, Chainsaw currently only displays the MDC when the sender is 
using log4j 1.3
 >
 > It would be trivial to write, I am willing to implement it, if there's a 
chance you will add it to logback.

In light of what you describe, I think using XML as an exchange format is quite 
reasonable. More importantly, it remains aligned with SLF4J's goal of 
abstracting/bridging logging systems.

You mention performance related results comparing XML formatting and Java 
serialization. I'd be interested in the figures.

ps: I'll be away for two weeks and without internet access.

 > regards,
 > Maarten
 >

-- 
Ceki Gülcü
Logback: The reliable, generic, fast and flexible logging framework for Java.
http://logback.qos.ch