Provide an Apache Commons Logging's LogFactory provider in spring-jcl to support WebSphere's Parent-First classloader [SPR-15903]

[spring-projects-issues]

Ibrahim Ghazal opened SPR-15903 and commented

In #19081 (specifically this comment), Juergen Hoeller said:

In "Parent First" mode, it's always WebSphere's own version of Commons Logging getting picked up. It does not make a difference whether the application contains a variant of Commons Logging itself: an application-level variant is always being ignored. Therefore it doesn't make a difference whether we embed our own variant versus JCL-over-X bridges or the standard Commons Logging jar.

In practice, there is a difference. When a real Commons Logging JAR is picked up (such as when using WebSphere's Parent-First classloader), spring-jcl is not used and spring's logs end up going to Commons Logging's default implementation (most likely JUL). But when log4j-jcl or jcl-over-slf4j are used instead of spring-jcl, logs are redirected to Log4j2 or SLF4J respectively.

This is because Commons Logging searches for a provider using the JAR Services Discovery mechanism (META-INF/services/org.apache.commons.logging.LogFactory file). Both log4j-jcl and jcl-over-slf4j provide this and so they just work even in such situations.

I think it's quite easy to provide this in spring-jcl too.

(The linked comment above mentions implementing the discovery mechanism in spring-jcl, but this issue is asking for the opposite (providing a provider)).

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Affects: 5.0 RC3

Issue Links:

• Allow spring-jcl to be found by Commons Logging's service discovery [SPR-16585] #21127 Allow spring-jcl to be found by Commons Logging's service discovery

Referenced from: commits 0b86c71

[spring-projects-issues]

Juergen Hoeller commented

This should finally be sorted out through #21127, with standard Commons Logging service discovery supported through a LogFactoryService class and a corresponding META-INF entry.

This will be available in the upcoming 5.1.0.BUILD-SNAPSHOT. Feel free to give it an early try, or otherwise in the official 5.1 RC1 release coming up in late July. Let's reopen this issue if any issues with JCL on WebSphere remain.