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SLF4J distribution changed in 3.7.x [message #1772292]

Thu, 07 September 2017 16:20

Nikolas Falco

Messages: 2
Registered: September 2017

Junior Member

Hi, I'm updating our Virgo Tomcat Server 3.6.4 to 3.7.2. We noticed a change in the distribution of the SFL4J libraries.

In 3.6.4 is distributed SLF4J with api, JUL, JCL and LOG4J extender. So that bundles that import java and apache loggers are redirected on SLF4J that logs delegating to an installed binder (logback).
The name of jar are in P2 form <bundle symbolic name>.<version with timestamp>.jar

org.slf4j.api_1.7.2.v20121108-1250
org.slf4j.jcl_1.7.2.v20121108-1250 (extender)
org.slf4j.jul_1.7.2.v20121108-1250 (extender)
org.slf4j.log4j_1.7.2.v20130115-1340 (extender)
org.slf4j.nop_1.7.2.v201212060727 (binder)
ch.qos.logback.slf4j_1.0.7.v20121108-1250 (binder)

The virgo 3.7.2 distribuites SLF4J with api and JUL extenders. So only bundles that import java loggers is redirect on SLF4J that delegates to one of the installed binder (JUL, LOG4J and LOGBACK).
The name of jar are in groovy form (maybe, are not maven)

slf4j_api-1.7.25
slf4j_jcl-1.7.25 (binder)
slf4j_log4j12-1.7.25 (binder)
jul_to-slf4j-1.7.25 (extender)
ch.qos.logback.classic_1.2.3 (binder)

Now the question is: Why the centralisation to SLF4J (that redirect logs on a single implementation) was removed?
What happen if a third party library logs to log4j ? Where is redirect it's log since log4j is not configured.

Maybe some changes in the compilation system led to the mistake of the JCL and LOG4J binders instead of the extender.

[Updated on: Fri, 08 September 2017 13:29]

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Re: SLF4J distribution changed in 3.7.x [message #1772380 is a reply to message #1772292]

Fri, 08 September 2017 13:20

GianMaria Romanato

Messages: 57
Registered: November 2015

Member

Hi Nikolas,

If I understand correctly you are saying that Virgo 3.7 is different from Virgo 3.6 because:

Virgo 3.6 shipped with Logback as the logging framework, used SLF4J for its own logging (delegating to logback), and also included some SLF4J bridges [1] for other popular logging frameworks (Jakarta Commons Logging, Log4j etc.) to ensure that any deployed bundle would be logging via SLF4J and therefore via Logback
Virgo 3.7 still includes Logback and SLF4J but you found out that it no more includes the bridges but instead it includes adapters to use JCL or Log4J instead of logback, which seems incorrect because you should only have one backend (logback) and bundles depending on e.g. log4j will now no more resolve unless the log4j bridge is added to the repository

and you are wondering whether this was done on purpose or was a mistake due to the confusing Jar names. Well, I don't know the answer, but maybe Daniel will comment on this.

[1] https://www.slf4j.org/legacy.html

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Re: SLF4J distribution changed in 3.7.x [message #1772383 is a reply to message #1772380]

Fri, 08 September 2017 13:30

Nikolas Falco

Messages: 2
Registered: September 2017

Junior Member

you understand it well

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Re: SLF4J distribution changed in 3.7.x [message #1772387 is a reply to message #1772383]

Fri, 08 September 2017 13:35

daniel marthaler

Messages: 77
Registered: April 2012
Location: Zürich

Member

Hi Nikolas,

It really looks as if the move away from ANT into Gradle caused this change. Can you please open a Bug for this, then will address this for 3.8.0.

Thanks
Dani

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