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https://issues.apache.org/jira/browse/BEAM-1092?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15729017#comment-15729017
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Maximilian Michels commented on BEAM-1092:
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2) is for avoiding user classes to clash with all SDK-related parts.
1) is for avoiding user classes to clash with other libraries added to the
classpath which do not properly shade common libraries (e.g. Hadoop)
The archetype does not become more complicated because of 1). It should be more
or less be transparent to the user who uses the archetype.
> Shade commonly used libraries (e.g. Guava) to avoid class conflicts
> -------------------------------------------------------------------
>
> Key: BEAM-1092
> URL: https://issues.apache.org/jira/browse/BEAM-1092
> Project: Beam
> Issue Type: Bug
> Components: examples-java, sdk-java-extensions
> Affects Versions: 0.3.0-incubating
> Reporter: Maximilian Michels
> Assignee: Frances Perry
> Fix For: 0.4.0-incubating
>
>
> Beam shades away some of its dependencies like Guava to avoid user classes
> from clashing with these dependencies. Some of the artifacts, e.g. KafkaIO,
> do not shade any classes and directly depend on potentially conflicting
> libraries (e.g. Guava). Also, users might manually add such libraries as
> dependencies.
> Runners who add classes to the classpath (e.g. Hadoop) can run into conflict
> with multiple versions of the same class. To prevent that, we should adjust
> the Maven archetypes pom files used for the Quickstart to perform shading of
> commonly used libraries (again, Guava is often the culprit).
> To prevent the problem in the first place, we should expand the shading of
> Guava and other libraries to all modules which make use of these.
> To solve both dimensions of the issue, we need to address:
> 1. Adding shading of commonly used libraries to the archetypes poms
> 2. Properly shade all commonly used libraries in the SDK modules
> 2) seems to be of highest priority since it affects users who simply use the
> provided IO modules.
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