Enabling Java 9 modularity

[svanteschubert]

Someone who is already using Java 9 modularity might assist us in adding this concept to the ODF Toolkit JARs.

See also: https://www.oracle.com/corporate/features/understanding-java-9-modules.html https://www.baeldung.com/java-9-modularity

[miasma]

At least for my simple use case, adding the following src/main/java/module-info.java seemed to work:

module org.odftoolkit.odfdom {
  requires java.desktop;
  requires java.logging;
  requires java.xml;
  requires java.rdfa;
  requires xercesImpl;
  requires org.json;
  requires org.slf4j;
  requires org.apache.jena.core;
  requires org.apache.commons.compress;
  requires org.apache.commons.lang3;
  requires commons.validator;
  requires serializer;

  exports org.odftoolkit.odfdom;
// and other exported packages
}

I had to disable the tests java/org/odftoolkit/odfdom/pkg/GRDDLTest.java and java/org/odftoolkit/odfdom/pkg/RDFMetadataTest.java since I couldn't figure out how to make the jena-core:tests visible (related: https://github.com/eclipse/jetty.project/issues/3080). While this is nice to have, it still won't work properly until [xercesImpl-2.12.0.jar, serializer-2.7.2.jar, java-rdfa-1.0.0-BETA1.jar, commons-validator-1.6.jar] have also migrated.

[svanteschubert]

Hello Miasma,

Thank you for your contribution and insights. So all our dependent project JARS you mentioned need to be transitioned to JDK 9 prior as well.

1. xercesImpl-2.12.0.jar & serializer-2.7.2.jar mentioned to be working
2. commons-validator-1.6.jar release notes for 1.7 mention a breaking change due to JDK 9 local usage - indicated they have JDK9 on the radar - I have not tested, but optimistic
3. No insight on Jena, likely we have to test the latest version and/or build locally with JDK 9 enabled and contribute it back
4. java-rdfa-1.0.0-BETA1.jar is from Damian Steer, who I once met. I just have written him about JDK 9 modules and the repo of https://repo1.maven.org/maven2/net/rootdev/java-rdfa/1.0.0-BETA1/ as the former repo seems still very old: https://github.com/shellac/java-rdfa (Update: https://github.com/iteggmbh/java-rdfa is the current repo)

Any further information & help is most welcome.

Best regards, Svante

[svanteschubert]

Damian answered the current RDFa GitHub repository, which is also creating the recent Maven artefact is: https://github.com/iteggmbh/java-rdfa

[wetneb]

I am new to Java 9 modularity, but I thought the following workaround could be of interest to others: If your project depends on odftoolkit and your IDE reports compilation errors due to Java modularity, you might want to exclude the xml-apis dependency from odftoolkit, which duplicates native libraries already provided by another module, as follows (for Maven):

     <dependency>
       <groupId>org.odftoolkit</groupId>
       <artifactId>odfdom-java</artifactId>
       <version>0.9.0-RC1</version>
      <exclusions>
        <exclusion>
          <groupId>xml-apis</groupId>
          <artifactId>xml-apis</artifactId>
        </exclusion>
      </exclusions>
     </dependency>

[svanteschubert]

Is anyone able to provide a pull request that enables Java 9 modularity? Or at least provide a pull request where we can iterate upon and list the remaining problems?

[wetneb]

I would like to understand what is the need you are looking into fulfilling here. I think Java 9 modularity can be "enabled" by adding some basic module metadata in module-info.java as mentioned by @miasma, but I do not know if such a setup would actually solve the issue you have in mind?

In other words, I would like to understand in which scenarios it is important to users that this Java 9 modularity is used.

[svanteschubert]

@wetneb Personally, I have no special use case in mind. I am happy to solve it with a patch based on the draft in the beginning. :-) When I did a quick test in VSCode to add the initially mentioned src/main/java/module-info.java I got a lot of errors, that some of the above mentioned would be not modules. That lead to my previous request for feedback/help.