Proper compatibility check for PROTOBUF_NATIVE schema

[visortelle]

Search before asking

• [X] I searched in the issues and found nothing similar.

Motivation

The current implementation checks only for changing a root message name.

https://github.com/apache/pulsar/blob/34c18704ce759922ce45820321af44b382a28e10/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/schema/ProtobufNativeSchemaCompatibilityCheck.java#L67-L72

It's definitely not enough. For example, these schemas won't be compatible due to the changed field type:

message Person {
  int32 age = 1;
  string name = 2;
}

message Person {
  int64 age = 1;
  string name = 2;

Of course, it's the simplest case. There are many more of them.

Solution

• Display in Pulsar docs that schema-compatibility-related policies don't work for PROTOBUF_NATIVE schema type. 👎

• Implement it in Java on your own. 👍

  Probably take buf.build rules is a good point to start. https://github.com/bufbuild/buf/blob/8b53bf721f3e21eedc3aef3eb0730fdf56d38064/private/bufpkg/bufcheck/bufbreaking/internal/bufbreakingcheck/bufbreakingcheck.go#L338

Alternatives

• Wait for a miracle 🪄 from Protobuf maintainers.
• Wait for a contribution from Apache Pulsar contributors.

Anything else?

I understand why it has been implemented this way. By quick googling, I didn't find any ready-to-use JVM-based Protobuf compatibility checkers.

In comparison, Avro has the org.apache.avro.SchemaValidator package.

Are you willing to submit a PR?

• [ ] I'm willing to submit a PR!

[Denovo1998]

Maybe I can give it a try.

[github-actions[bot]]

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