Hadoop/Elephas is an example of a general problem with Guava. By
reputation, upgrading Guava across versions has been problematic -
subtle and not-so-subtle changes of behaviour or removed code.
When Jena is used as a library, the system or application in which it is
used might use Guava itself - and need a specific version. But Jena
uses Guava and needs a specific version with certain code in it, which
might be different.
We are isolating Jena's use of Guava from the system in which Jena is
used. Hadoop's have very strong requirements on Guava versions - it
might well apply to other user applications as well.
We do <exclude/> in the sense that dependency-reduced-pom.xml POM of
jena-shared-guava does not mention com.google.guava:guava. Elephas picks
up the Hadoop dependency.
Andy
On 08/06/15 14:26, aj...@virginia.edu wrote:
I think the idea of breaking the shaded Guava artifact out of the
main cycle is great. It's clearly not a subject of work under most
circumstances and having one less moving part in a developer's mix is
usually a good thing, especially for the simple-minded ({raises hand}).
Is it only Hadoop's Guava that is at issue? Would it be possible
perhaps to just <exclude/> Guava from the Hadoop dependencies in
Elephas? Or does that blow up Hadoop? Or should I go experiment and find
out?
---
A. Soroka
The University of Virginia Library
On Jun 8, 2015, at 9:21 AM, Andy Seaborne <a...@apache.org> wrote:
Ah right. To summarise what is happening:
The POM file in the maven repo is not the POM file in git.The shade plugin
produces a different POM for the the output artifact with the shaded dependency
removed.
When the project is not open, Eclipse sees the reduced POM, which does not have a
<dependency> on Google Guava.
When the module jena-shaded-guava is open in Eclipse, Eclipse sees the POM in the
module source which names the dependent Google Guava in a <dependency>.
Result: a certain degree of chaos.
Andy
On 06/06/15 03:19, Stian Soiland-Reyes wrote:
Yes, you would need to keep the jena-guava project closed so you get the
Maven-built shaded jar on the classpath, which has the shaded package name,
otherwise you will just see the upstream Guava through Eclipse's project
sharing.
The package name is not shaded for OSGi, it is easy to define private
packages there. It is shaded to avoid duplicate version mismatches against
other dependencies with "the real guava", e.g. Hadoop which as you know has
an ancient Guava.
It might be good to keep it out of the normal build/release cycle, then you
would get the jena-guava shade from Maven central, which should only change
when we upgrade Guava, in which case it could be re-enabled in the SNAPSHOT
build or vote+released as a separate artifact (which might be slightly odd
as it contains no Jena contributions beyond the package name)
On 4 Jun 2015 14:33, "aj...@virginia.edu" <aj...@virginia.edu> wrote:
I have had this problem since I began tinkering. The only solution I have
found is make sure that the jena-shaded-guava project is never open when
any project that refers to types therein is open. This isn't much of a
burden, and I suppose it has something to do with the Maven magic that is
going on inside jena-shaded-guava.
I'm not totally clear as to why Jena shades Guava into its own namespace--
is it to avoid OSGi-exporting Guava packages? (We have something like that
going on in another project on which I work.)
---
A. Soroka
The University of Virginia Library
On Jun 4, 2015, at 9:22 AM, Rob Vesse <rve...@dotnetrdf.org> wrote:
Folks
Recently I've been having a lot of trouble getting Jena to build in
Eclipse
which seems to be due to the use of the Shade plugin to Shade Guava. Any
module that has a reference to the shaded classes ends refuses to build
with
various variations of the following error:
java.lang.NoClassDefFoundError:
org/apache/jena/ext/com/google/common/cache/RemovalNotification
Anybody else been having this issue? If so how did you resolve it?
Sometimes cleaning my workspace and/or doing a mvn package at the command
line seems to help but other times it doesn't
Rob
