Remote subgraph traversal

[phreed]

The ability to return subgraphs is not possible because the TinkerIoRegistryV3d0 is not included in the gremlin-server.yaml.

serializers:
...
  - className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0
    config:
      ioRegistries:
        - org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry
        - org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0
...

As was pointed out by @mkaisercross a similar behavior can be achieved with environment parameters.
The question is whether subgraph serialization should be allowed by default or not.

docker run -it -e gremlinserver.serializers[2].config.ioRegistries[+]=org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0 janusgraph/janusgraph:latest janusgraph show-config

[linux-foundation-easycla]

• ✅ Fred Eisele (8f5495b, 67fd9b4, 45aa9cf, 3cb6225)

• ❌ The commit (50c49a8 ,b44cfe21462eea35979f74d88879bcff27bb223e ,5e6f28971882bfb0a6eb55eeba1f4f7155e60b6b ,cdec48b1f3574f0464eb06b271fe2dac6c17ed4c) is missing the User's ID, preventing the EasyCLA check. Consult GitHub Help to resolve.For further assistance with EasyCLA, please submit a support request ticket.

[phreed]

I am doing my development (mostly) on Windows 10. When I did anything with a text file it would replace the LF with CRLF which causes some problems for docker. To prevent this I added the .gitattributes file https://git-scm.com/docs/gitattributes .
Apparently weasel has a problem with this!? Please advise.

[phreed]

* ✅  Fred Eisele ([8f5495b](https://github.com/JanusGraph/janusgraph-docker/commit/8f5495bbfca0a149b776473c869b9519fef6c462), [67fd9b4](https://github.com/JanusGraph/janusgraph-docker/commit/67fd9b462d7366e3c455f00b440a80abb2c85997))


* ❌ The commit ([50c49a8](https://github.com/JanusGraph/janusgraph-docker/commit/50c49a8621f10622574542ccda3fc16d5a874cef) ,b44cfe21462eea35979f74d88879bcff27bb223e ,5e6f28971882bfb0a6eb55eeba1f4f7155e60b6b) is missing the User's ID, preventing the EasyCLA check. [Consult GitHub Help](https://help.github.com/en/github/committing-changes-to-your-project/why-are-my-commits-linked-to-the-wrong-user) to resolve.For further assistance with EasyCLA, [please submit a support request ticket](https://jira.linuxfoundation.org/servicedesk/customer/portal/4).

I do not see how to update my User ID in the previous commits.
I cannot open a EasyCLA support request ticket.
Please advise.

[FlorianHockmann]

To prevent this I added the .gitattributes file https://git-scm.com/docs/gitattributes .
Apparently weasel has a problem with this!? Please advise.

Weasel verifies that all files have a license header but license headers don't make sense for some files to they can be excluded from this check in the .dependency_license file. We also did that for the .gitignore file for example so you could do the same here to add a .gitattributes file.

I do not see how to update my User ID in the previous commits.
I cannot open a EasyCLA support request ticket.

Please just squash your commits into a single one. While doing that, git should use your current config and therefore set the user ID correctly. We prefer to have a single commit per contribution anyway to have a clean commit history.

If you need help with squashing your commits, the easiest option in my opinion looks like this:

git reset --soft HEAD~8
git commit -s
git push --force

This resets the last 8 commits while keeping their changes and then commits them again with a single commit. That commit is afterwards force pushed which will overwrite the existing 8 commits on your remote branch.

The -s for git commit is also important to note here. It simply adds a Signed-off-by: line to your commit message to sign your commit. This is a requirement we have to accept a contribution. The DCO check verifies that a commit is signed like this which is currently also failing here.

[FlorianHockmann]

JanusGraph Server now configures the serializers automatically if no config is set in its config YAML:
https://docs.janusgraph.org/changelog/#introduction-of-a-janusgraph-server-startup-class-as-a-replacement-for-gremlin-server-startup

which is why the Docker images also don't configure the serializers any more.

In general, this is not really an issue with the Docker image, but for JanusGraph in general and we also already have an open issue for that: JanusGraph/janusgraph#2843.

So, I'm closing this PR.