Website: API Separation - "Using Log4j2 as an SLF4J Implementation" is outdated/misleading (SLF4J particularly)

[Chealer]

Description

The Using Log4j2 as an SLF4J Implementation section of the website's API Separation page contains several outdated elements. For starters, Log4j 2.17 itself is fairly outdated, but most importantly, 1.7.32 is obsoleted by both 1.7.36 and SLF4J 2.

The worse problem is the section refers to SLF4J 1.8, which was never released:

Note that if we were using SLF4J 1.8 instead of 1.7, that requires us to use log4j-slf4j18-impl instead of log4j-slf4j-impl.

However, SLF4J does have version 2, which should not only be documented, but considered the default choice at this point.

I know that POMs (Maven) force precise version so this section is doomed to remain either frequently outdated or costly to maintain (unless versions are removed, perhaps replaced by ellipses). But a note indicating that the versions are likely outdated would help.

If I understand this section correctly, it should mention the term "provider", used by SLF4J to designate an "SLF4J implementation".

[ppkarwasz]

@Chealer,

Thanks for the remarks. Since we use Maven Site Plugin, we can replace the static api-separation.md file with a Velocity template and use the currently used version of all components. The version of all dependencies are kept as Maven POM properties.

I agree that SLF4J 2.x should be the default one, although I wouldn't completely remove references to the 1.x series: it still has advantages, like out-of-the-box OSGI support without relying on the optional Service Loader Mediator.

IMHO terms like "adapter", "bridge", "binding" (used in SLF4J 1.x), "provider" (used in SLF4J 2.x) and "implementation" are really confusing. If I want to connect X to Y I never remember if I should look for an "X bridge", "X adapter" or "X binding". I would rather use a single expression like "X to Y adapter" that clearly states that the component forwards API X calls to backend Y.

I think we could we could start the example section with a graph representing all possible connections. This could roughly look like this with hyperlinks to the appropriate sections.

From				To/From				To
SLF4J 2.x	→	log4j-slf4j2-impl	↘		↗	→	→	Log4j 2.x Core
SLF4J 1.7.x	→	log4j-slf4j-impl	→	Log4j 2.x API	→	log4j-to-slf4j	→	SLF4J	→	Logback
JUL	→	log4j-jul	↗		↘	log4j-to-jul	→	JUL
JCL	→	log4j-jcl	↗
JPL	→	log4j-jpl	↗

If someone wants to look into it, we love PRs.

[vy]

Fixed by several changes implemented for #2535.