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https://issues.apache.org/jira/browse/DAFFODIL-2787?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Steve Lawrence resolved DAFFODIL-2787.
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Resolution: Fixed
Fixed in 10b74f4fc6ff5a12e2f7bd24e053631deebd714a
There is no longer a log4j dependency, so version mismatches are not a problem.
We now use slf4j and a custom slf4j backed for tdml processors. DFDL Schema
projects depending on log4j-core can now remove that dependency, though it
won't hurt anything if it exists.
> log4j-core and log4j-api version mismatch can lead to very confusing errors
> ---------------------------------------------------------------------------
>
> Key: DAFFODIL-2787
> URL: https://issues.apache.org/jira/browse/DAFFODIL-2787
> Project: Daffodil
> Issue Type: Bug
> Components: Infrastructure
> Affects Versions: 3.4.0
> Reporter: Steve Lawrence
> Assignee: Steve Lawrence
> Priority: Major
> Fix For: 3.5.0
>
>
> Daffodil libs do not explicitly depend on log4j-core, with the reason being
> that users can provide whatever log4j implementation that they want (maybe
> there's something else aside from log4j-core?)
> The problem with this is that if projects that depend on daffodil do not also
> depend on a log4j implementation then they get a warning like this:
> {quote}ERROR StatusLogger Log4j2 could not find a logging implementation.
> Please add log4j-core to the classpath. Using SimpleLogger to log to the
> console...
> {quote}
> For this reason, many schema projects add an explicit log4j-core dependency
> to suppress this warning. However, if the version of log4j-core they depend
> on does not match the version of log4j-api that Daffodil uses then you get a
> really verbose, unhelpful, and probably wrong, error message about
> classLoaderLayeringStrategy. And this is fairly common since we frequently
> update our dependencies but schema projects tend to lag behind.
> We need to either have a dependency on log4j-core so schema projects don't
> need to worry about adding this depend and matching versions, or use some
> other dependency mechanism to ensure whatever log4j implementation is used
> matches our log4j-api version.
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