Lewis John McGibbney created NUTCH-3034:
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Summary: Overhaul the legacy Nutch plugin framework and replace it
with PF4J
Key: NUTCH-3034
URL: https://issues.apache.org/jira/browse/NUTCH-3034
Project: Nutch
Issue Type: Improvement
Components: pf4j, plugin
Reporter: Lewis John McGibbney
h1. Motivation
Plugins provide a large part of the functionality of Nutch. Although the legacy
plugin framework continues to offer lots of value i.e.,
# [some aspects e.g. examples, are fairly well
documented|[https://cwiki.apache.org/confluence/display/NUTCH/PluginCentral]]
# it is generally stable, and
# offers reasonable test coverage (on a plugin-by-plugin basis)
# … probably loads more positives which I am overlooking...
… there are also several aspects which could be improved
# the [core framework is sparsely
documented|[https://cwiki.apache.org/confluence/display/NUTCH/WhichTechnicalConceptsAreBehindTheNutchPluginSystem]],
this extends to very important aspects like the {*}plugin lifecycle{*},
{*}classloading{*}, {*}packaging{*}, \{*}thread safety{*}, and lots of other
topics which are of intrinsic value to developers and maintainers.
# the core framework is somewhat [sparsely
tested|[https://github.com/apache/nutch/blob/master/src/test/org/apache/nutch/plugin/TestPluginSystem.java]]…
only 7 tests. Traditionally, developers have focused on providing unit tests
on the plugin-level as opposed to the legacy plugin framework.
# see’s very low maintenance/attention. It is my gut feeling (and I may be
totally wrong here) but I _think_ that not many people know much about the core
legacy plugin framework.
# writing plugins is clunky. This largely has to do with the legacy Ant + Ivy
build and dependency management system, but that being said, it is clunky
non-the-less.
*This issue therefore proposes to overhaul the* *legacy* *Nutch plugin
framework and replace it with Plugin Framework for Java (PF4J).*
h1. Task Breakdown
The following is a proposed breakdown of this overall initiative intp Epics.
These Epics should likely be decomposed further but that will be left down to
the implementer(s).
* {*}perform feasibility study{*}; touch base with the PF4J community,
describe the intention to replace the legacy Nutch plugin framework with PF4J.
Obtain guidance on how to proceed. Document this all in the Nutch wiki.
* {*}document the legacy Nutch plugin lifecycle{*}; taking inspiration from
[PF4J’s plugin lifecycle
documentaiton|[https://pf4j.org/doc/plugin-lifecycle.html]] provide both
documentation and a diagram which clearly outline how the legacy plugin
lifecycle works. Might also be a good idea to make a contribution to PF4J and
provide them with a diagram to accompany their documentation :)
*
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