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Apache Jena
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[question] OWL2 support in Apache Jena #1968

Closed sszuev closed 5 months ago

sszuev commented 1 year ago

Version

4.x.x

Question

One more question.

I've already raised this issue in Dev ML (can't find the link right now). There was no final decision, or I missed it. I think it would not be bad if this issue is open again for discussion here.

Here is ONT-API. ONT-API is an RDF-centric Java library to work with OWL2. It's alternative implementation of OWL-API. Each ontology has an RDF org.apache.jena.graph.Graph underlying.

The library consists of two parts: com.github.owlcs.ontapi.jena.model.OntModel (jena RDF Model, similar to the org.apache.jena.ontology.OntModel) and com.github.owlcs.ontapi.Ontology (extended OWL-API OWLOntology). The second part (i.e. the implementation of OWL-API itself) depends on the first one.

Perhaps the first part, ONT-API's OntModel, would look organically in Apache Jena itself (as an replacement Jena's OntModel, which does not support OWL2).

The problem here is that ONT-API's OntModel covers OWL2 syntax, but that's all. There is no support for Jena-rules, different specs, etc. To close this gap I started a new project: https://github.com/sszuev/jena-owl2 It's still under developing, so this question is preliminary, maybe it is raised too early.

In any case, if this could be a part of Apache Jena, then the development could be adjusted for this purpose (via feedbacks, reviews, recommendations, etc). Otherwise, I will keep in mind that the project jena-owl2 will be a separated library.

afs commented 1 year ago

I've already raised this issue in Dev ML (can't find the link right now).

https://lists.apache.org/thread/ztfvvz55oz3xmddtrpkfowtsgo9czg5n

afs commented 1 year ago

Maybe you describe ONT-API briefly on this PR. Is it for managing an ontology - not for executing inference? That's not an issue - we just have to be clear what it is and what it isn't.

From the previous discussion, I don't see anything that a blocker. I'm not completely sure what the permissions connection is - it is for Model, not OntModel anyway.

sszuev commented 1 year ago

1) A couple words about OWL-API and ONT-API, once again.

Each org.semanticweb.owlapi.model.OWLOntology provides access to org.semanticweb.owlapi.model.OWLAxioms which, in turn, consist of org.semanticweb.owlapi.model.OWLObjects. There are 38 types of OWL2 axioms + SWRL-Rule "axiom". In the default OWLAPI-impl each OWLOntology is a set of OWLAxioms, everything is stored in memory.

There is a generic interface org.semanticweb.owlapi.reasoner.OWLReasoner. In OWLAPI there are several limited implementations. + Also, there are several external, advanced, implementations of OWLReasoner: jfact, hermit, openllet.

ONT-API is an alternative implementation of OWLAPI-api. There is no any reasoner, but of course it can be used by any OWLReasoner.

In ONT-API there are tree layers:

Thanks to the fact that we have RDF under the hood, we can use OWL2 together with SHACL, SPARQL, etc. Also, any Graph could underlay, not only in-memory implementations. If some RDF construction does not meet the OWL2 specification, it is invisible from the top-level of ONT-API.

There is concurrent support via ReadWriteLock, but only for the first level (ReadWriteLockingGraph) and the last one.

I think, the whole ONT-API's code is not very suitable to be merged into Jena. But second level (Jena's extended Model) could be, it is closer to what Jena already has.

2) Here is a spin-off of ONT-API - https://github.com/sszuev/jena-owl2 project. It contains second level: extended Jena Model - com.github.sszuev.jena.ontapi.model.OntModel The goal of this project is to repeat all the org.apache.jena.ontology.OntModel's functionality, including rules-inference support, different specs, document-manager, etc. It is currently under development. At the moment there are only OWL2_MEM, RDFS_MEM and OWL2_DL_MEM_RDFS_BUILTIN_INF specs. OntModel is not InfModel yet. ReadWriteLockingGraph will not be part of this model-api (at least in the first release).

OntModel interface supports all the feature of OWL2 and also SWRL (since it is present in OWLAPI).

Example:

OntModel m = OntModelFactory.createModel().setNsPrefixes(OntModelFactory.STANDARD);
m.createDataAllValuesFrom(List.of(m.createDataProperty("dp")), m.createDataRestriction(m.getDatatype(XSD.xstring),
                m.createFacetRestriction(OntFacetRestriction.MaxLength.class, m.createTypedLiteral(42))))
        .addEquivalentClass(m.createOntClass("C"));
m.ontObjects(OntClass.class).forEach(System.out::println);
m.ontEntities().forEach(System.out::println);
m.write(System.out, "ttl");

For more examples see wiki https://github.com/owlcs/ont-api/wiki

There are no OWLAxiom objects, just like in org.apache.jena.ontology.OntModel. There is com.github.sszuev.jena.ontapi.UnionGraph, any changes in imported ontologies (owl:import) are visible in the top-level.

For developing I use Jena's OntModel tests (tests rewritten and expanded with new tests): https://github.com/sszuev/jena-ont-tests org.apache.jena.ontology.OntModel's documentation, and sometimes its implementation (but usually it is difficult to understand that code, it's easier to write from scratch)

afs commented 10 months ago

General issue for OWL2 support: #2160

sszuev commented 10 months ago

The first version of jena-owl2 library is ready: https://github.com/sszuev/jena-owl2 It supports all the features of the legacy OntModel. Model's level support for QL, RL, EL will be added later. Any feedback is welcome.

sszuev commented 8 months ago

Model's level support for QL, RL, EL is added.

sszuev commented 8 months ago

Benchmarks reflecting the current state:

Benchmark                                                                 (factory)   Mode  Cnt        Score       Error  Units
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_DIRECT                     OWL2_FULL_MEM  thrpt   20     1923,911 ?    15,964  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_DIRECT                       OWL2_EL_MEM  thrpt   20     2032,108 ?    21,342  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_DIRECT                     OWL1_LITE_MEM  thrpt   20     1398,018 ?    10,840  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_DIRECT            OWL2_FULL_MEM_RDFS_INF  thrpt   20        1,016 ?     0,014  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_DIRECT           OWL2_DL_MEM_BUILTIN_INF  thrpt   20      956,433 ?    10,871  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_DIRECT                    LEGACY_OWL_MEM  thrpt   20    11215,546 ?   187,824  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_DIRECT        LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20        1,012 ?     0,014  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_INDIRECT                   OWL2_FULL_MEM  thrpt   20     3514,486 ?    57,036  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_INDIRECT                     OWL2_EL_MEM  thrpt   20     3902,678 ?    45,094  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_INDIRECT                   OWL1_LITE_MEM  thrpt   20     2162,491 ?    74,462  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_INDIRECT          OWL2_FULL_MEM_RDFS_INF  thrpt   20        1,050 ?     0,017  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_INDIRECT         OWL2_DL_MEM_BUILTIN_INF  thrpt   20     1136,866 ?     6,205  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_INDIRECT                  LEGACY_OWL_MEM  thrpt   20    90239,833 ?  3020,189  ops/s
JmhClassIndividuals.LIST_CLASS_INDIVIDUALS_INDIRECT      LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20        9,621 ?     0,284  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_DIRECT                 OWL2_FULL_MEM  thrpt   20      602,578 ?    13,858  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_DIRECT                   OWL2_EL_MEM  thrpt   20      603,486 ?    15,590  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_DIRECT                 OWL1_LITE_MEM  thrpt   20      552,208 ?     9,938  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_DIRECT        OWL2_FULL_MEM_RDFS_INF  thrpt   20        2,175 ?     0,346  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_DIRECT       OWL2_DL_MEM_BUILTIN_INF  thrpt   20      577,964 ?    10,668  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_DIRECT                LEGACY_OWL_MEM  thrpt   20      941,769 ?    37,638  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_DIRECT    LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20       27,630 ?     0,534  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_INDIRECT               OWL2_FULL_MEM  thrpt   20      609,576 ?     8,358  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_INDIRECT                 OWL2_EL_MEM  thrpt   20      597,792 ?     7,936  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_INDIRECT               OWL1_LITE_MEM  thrpt   20      540,492 ?    17,052  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_INDIRECT      OWL2_FULL_MEM_RDFS_INF  thrpt   20        2,526 ?     0,632  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_INDIRECT     OWL2_DL_MEM_BUILTIN_INF  thrpt   20      576,449 ?     3,365  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_INDIRECT              LEGACY_OWL_MEM  thrpt   20      998,556 ?    47,192  ops/s
JmhDeclaredProperties.LIST_DECLARED_PROPERTIES_INDIRECT  LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20       27,028 ?     0,679  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_DIRECT                      OWL2_FULL_MEM  thrpt   20      739,950 ?     6,990  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_DIRECT                        OWL2_EL_MEM  thrpt   20      750,253 ?     9,197  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_DIRECT                      OWL1_LITE_MEM  thrpt   20      853,760 ?     6,403  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_DIRECT             OWL2_FULL_MEM_RDFS_INF  thrpt   20       26,372 ?     0,746  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_DIRECT            OWL2_DL_MEM_BUILTIN_INF  thrpt   20      388,656 ?     3,079  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_DIRECT                     LEGACY_OWL_MEM  thrpt   20     2130,594 ?    31,712  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_DIRECT         LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20       51,955 ?     1,049  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_INDIRECT                    OWL2_FULL_MEM  thrpt   20     3708,437 ?    40,225  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_INDIRECT                      OWL2_EL_MEM  thrpt   20     4092,354 ?    23,170  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_INDIRECT                    OWL1_LITE_MEM  thrpt   20    17765,737 ?   242,984  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_INDIRECT           OWL2_FULL_MEM_RDFS_INF  thrpt   20      117,545 ?     5,883  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_INDIRECT          OWL2_DL_MEM_BUILTIN_INF  thrpt   20     3486,673 ?    96,499  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_INDIRECT                   LEGACY_OWL_MEM  thrpt   20     8103,053 ?   191,609  ops/s
JmhDeclaringClasses.LIST_DECLARED_CLASSES_INDIRECT       LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20      168,471 ?     5,150  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_DIRECT                   OWL2_FULL_MEM  thrpt   20   194416,995 ?  4152,421  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_DIRECT                     OWL2_EL_MEM  thrpt   20   192425,384 ?  5128,301  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_DIRECT                   OWL1_LITE_MEM  thrpt   20   157829,681 ?  1869,907  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_DIRECT          OWL2_FULL_MEM_RDFS_INF  thrpt   20      683,222 ?    31,047  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_DIRECT         OWL2_DL_MEM_BUILTIN_INF  thrpt   20    87477,583 ?  1256,418  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_DIRECT                  LEGACY_OWL_MEM  thrpt   20   288554,472 ?  4034,018  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_DIRECT      LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20      232,062 ?     9,360  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_INDIRECT                 OWL2_FULL_MEM  thrpt   20  1061883,645 ? 11899,620  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_INDIRECT                   OWL2_EL_MEM  thrpt   20   979498,876 ? 22328,129  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_INDIRECT                 OWL1_LITE_MEM  thrpt   20   600111,538 ? 10245,863  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_INDIRECT        OWL2_FULL_MEM_RDFS_INF  thrpt   20      323,415 ?    14,609  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_INDIRECT       OWL2_DL_MEM_BUILTIN_INF  thrpt   20    33709,495 ?   329,313  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_INDIRECT                LEGACY_OWL_MEM  thrpt   20   532256,642 ?  9438,609  ops/s
JmhIndividualClasses.LIST_INDIVIDUAL_CLASSES_INDIRECT    LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20      193,377 ?     8,711  ops/s
JmhListClasses.LIST_ALL_CLASSES                                       OWL2_FULL_MEM  thrpt   20     3913,181 ?    54,105  ops/s
JmhListClasses.LIST_ALL_CLASSES                                         OWL2_EL_MEM  thrpt   20     4280,284 ?    20,349  ops/s
JmhListClasses.LIST_ALL_CLASSES                                       OWL1_LITE_MEM  thrpt   20    21437,334 ?   702,863  ops/s
JmhListClasses.LIST_ALL_CLASSES                              OWL2_FULL_MEM_RDFS_INF  thrpt   20      123,030 ?     4,547  ops/s
JmhListClasses.LIST_ALL_CLASSES                             OWL2_DL_MEM_BUILTIN_INF  thrpt   20     3671,583 ?    72,838  ops/s
JmhListClasses.LIST_ALL_CLASSES                                      LEGACY_OWL_MEM  thrpt   20     9994,878 ?   272,441  ops/s
JmhListClasses.LIST_ALL_CLASSES                          LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20      266,424 ?     6,418  ops/s
JmhListClasses.LIST_NAMED_CLASSES                                     OWL2_FULL_MEM  thrpt   20    34730,936 ?  1610,608  ops/s
JmhListClasses.LIST_NAMED_CLASSES                                       OWL2_EL_MEM  thrpt   20    36848,320 ?   635,520  ops/s
JmhListClasses.LIST_NAMED_CLASSES                                     OWL1_LITE_MEM  thrpt   20    23413,521 ?   486,528  ops/s
JmhListClasses.LIST_NAMED_CLASSES                            OWL2_FULL_MEM_RDFS_INF  thrpt   20      993,880 ?    47,671  ops/s
JmhListClasses.LIST_NAMED_CLASSES                           OWL2_DL_MEM_BUILTIN_INF  thrpt   20    32552,578 ?  1775,482  ops/s
JmhListClasses.LIST_NAMED_CLASSES                                    LEGACY_OWL_MEM  thrpt   20     9877,561 ?   285,693  ops/s
JmhListClasses.LIST_NAMED_CLASSES                        LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20      259,240 ?     6,974  ops/s
JmhListIndividuals.LIST_INDIVIDUALS                                   OWL2_FULL_MEM  thrpt   20     2753,444 ?    31,634  ops/s
JmhListIndividuals.LIST_INDIVIDUALS                                     OWL2_EL_MEM  thrpt   20     2969,503 ?    28,523  ops/s
JmhListIndividuals.LIST_INDIVIDUALS                                   OWL1_LITE_MEM  thrpt   20     1769,376 ?    46,018  ops/s
JmhListIndividuals.LIST_INDIVIDUALS                          OWL2_FULL_MEM_RDFS_INF  thrpt   20        0,933 ?     0,006  ops/s
JmhListIndividuals.LIST_INDIVIDUALS                         OWL2_DL_MEM_BUILTIN_INF  thrpt   20     2711,182 ?    37,211  ops/s
JmhListIndividuals.LIST_INDIVIDUALS                                  LEGACY_OWL_MEM  thrpt   20     1333,065 ?    14,264  ops/s
JmhListIndividuals.LIST_INDIVIDUALS                      LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20        0,017 ?     0,001  ops/s
JmhSubClasses.LIST_SUB_CLASSES_DIRECT                                 OWL2_FULL_MEM  thrpt   20     1131,328 ?    18,373  ops/s
JmhSubClasses.LIST_SUB_CLASSES_DIRECT                                   OWL2_EL_MEM  thrpt   20     1128,517 ?    18,958  ops/s
JmhSubClasses.LIST_SUB_CLASSES_DIRECT                                 OWL1_LITE_MEM  thrpt   20     1080,470 ?    11,340  ops/s
JmhSubClasses.LIST_SUB_CLASSES_DIRECT                        OWL2_FULL_MEM_RDFS_INF  thrpt   20       48,010 ?     0,615  ops/s
JmhSubClasses.LIST_SUB_CLASSES_DIRECT                       OWL2_DL_MEM_BUILTIN_INF  thrpt   20       86,404 ?     0,896  ops/s
JmhSubClasses.LIST_SUB_CLASSES_DIRECT                                LEGACY_OWL_MEM  thrpt   20     3552,075 ?   121,430  ops/s
JmhSubClasses.LIST_SUB_CLASSES_DIRECT                    LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20       19,666 ?     0,395  ops/s
JmhSubClasses.LIST_SUB_CLASSES_INDIRECT                               OWL2_FULL_MEM  thrpt   20    96706,467 ?  1448,771  ops/s
JmhSubClasses.LIST_SUB_CLASSES_INDIRECT                                 OWL2_EL_MEM  thrpt   20    80929,295 ?  2835,746  ops/s
JmhSubClasses.LIST_SUB_CLASSES_INDIRECT                               OWL1_LITE_MEM  thrpt   20    44455,080 ?   637,873  ops/s
JmhSubClasses.LIST_SUB_CLASSES_INDIRECT                      OWL2_FULL_MEM_RDFS_INF  thrpt   20      164,218 ?     2,610  ops/s
JmhSubClasses.LIST_SUB_CLASSES_INDIRECT                     OWL2_DL_MEM_BUILTIN_INF  thrpt   20     5624,272 ?    45,155  ops/s
JmhSubClasses.LIST_SUB_CLASSES_INDIRECT                              LEGACY_OWL_MEM  thrpt   20    49828,475 ?  1656,329  ops/s
JmhSubClasses.LIST_SUB_CLASSES_INDIRECT                  LEGACY_OWL_DL_MEM_RDFS_INF  thrpt   20      159,887 ?     3,668  ops/s
sszuev commented 7 months ago

Any update on this case? I ask because my work depends on the final resolution. If approve I will think about free time to prepare PR, if reject I would like to know the reasons, in that last case I would improve the library according to the feedback, or leave it as is, having opportunity to observe the duplication of the functionality by Jena.

rvesse commented 7 months ago

Any update on this case? I ask because my work depends on the final resolution. If approve I will think about free time to prepare PR,

If I'm being perfectly honest I think it's mainly because nobody active in the project has enough OWL background/interest to meaningfully review the code.

Remember that everyone who is a commuter or PMC member is purely a volunteer, while several of us have $dayjob's that involve working with Jena, none of us is directly paid by our employers specifically to do Jena work. Therefore we all tend to focus our efforts on things that affect us, bugs with widespread impact, or things that are easy to address, thus larger new features that we personally have no need for are hard to find time for.

if reject I would like to know the reasons, in that last case I would improve the library according to the feedback,

From glancing over your repository my main concern is that it appears to duplicate a lot of code from ONT-API, presumably to avoid creating a circular dependency since ONT-API already relies on Jena. Could that be achieved differently by making the Jena OWL 2 support a new Jena module that pulls in the dependency on ONT-API (explicitly excluding its own Jena dependency) so you'd get all the supporting code you need from there without duplication? As long as ONT-API is keeping reasonably aligned with Jena releases (and Jena doesn't break any APIs it relies on in a release) things should work.

As a general consideration accepting large contributions of this nature is tricky, especially when none of the active committers have the necessary background/interest to maintain it going forward, so we have to try and gauge whether there's enough community interest (beyond you as a contributor) in actually using and maintaining it.

or leave it as is, having opportunity to observe the duplication of the functionality by Jena.

Realistically Jena won't get OWL 2 support unless someone like yourself provides a PR for it. So I'm not against this proposal in any sense, I just don't have the background to do anything more than a perfunctory review.

sszuev commented 7 months ago

From glancing over your repository my main concern is that it appears to duplicate a lot of code from ONT-API, presumably to avoid creating a circular dependency since ONT-API already relies on Jena.

There is no duplication of code. Since version 3.5.0 ONT-API uses Jena-OWL2 as a dependency. These libraries are responsible for different functionality: Jena-OWL2 runs RDF and InfGraph, while ONT-API runs OWLAxioms. If/when new OntModel appears in Jena, ONT-API will use it directly.

afs commented 7 months ago

I'd like to see OWL2 support in Jena.

If/when new OntModel appears in Jena

Realistically - it's not going to happen anytime soon. Compatibility/stability is important to many Jena users. Adding a new module for OWL2 would be less constraining on the OWL2 features and no API migration lockstep.

Jena has the loose concept of "core modules" and "extra modules". "Core" is roughly those upto the Fuseki server binaries.

"Extra modules" are at risk of being removed if they don't get maintenance. We do have "one person" extra modules already.

I pulled down https://github.com/sszuev/jena-owl2 and "mvn install" worked. Updating to Jena 5.0.0 didn't work but no surprises.

mvn dependency:tree doesn't look too worrying.

Not touching net.sourceforge.owlapi is good! - net.sf.owlapi has some worrying license issues.

sszuev commented 6 months ago

To help with the investigation and review, I have created a PR https://github.com/apache/jena/pull/2420. This is basically a copy-paste, and the alignment with the Jena rules and integration (e.g., moving/renaming vocabularies) can be done later to avoid conflicts when rebasing. All commits have been copied. Squashing can be made before merging (but I'd preserve history, it is important for investigation).
Also, there is jena-5.x.x branch in the original (https://github.com/sszuev/jena-owl2) repo.

afs commented 5 months ago

OWL2 support is now in the codebase thanks to the work by @sszuev. It will be released in Jena version 5.1.0.