Serializing google.protobuf.Any for visualization in Foxglove Studio

[tervay-bdai]

I'm attempting to (in C++) serialize a protobuf utilizing google.protobuf.Any as a type, in order to view in Foxglove. For example:

message Foo {
  google.protobuf.Any bar = 1;
}

message Baz {
  repeated int32 buzz = 1;
}

I would like to insert a Baz instance into Foo::bar and plot foo.bar.buzz in Foxglove. Unfortunately, Foxglove doesn't recognize any schemas for the type:

I suspect this is because I am not actually ever telling mcap about the protobuf schemas from the message types packed into the Any - I'm only registering Foo's schema, which doesn't know anything about any other types, because, well, bar can be anything.

I've taken a read through the mcap protobuf guide and the examples, but I'm not totally seeing a way to register multiple proto schemas.

Is this a supported workflow? If so, how would one achieve this?

[jtbandes]

Hi,
Currently, we don't have any support for google.protobuf.Any and you would need to create a separate schema and channel for each type. One difficulty in supporting google.protobuf.Any is that Foxglove Studio needs to know the whole protobuf descriptor (formatted as a FileDescriptorSet) in order to deserialize message data. Simply type_url: "type.googleapis.com/bdai.mcap.Child" is not enough information to deserialize messages, unless the app can somehow access the full descriptor for bdai.mcap.Child somewhere.

[tervay-bdai]

Thank you for the info. I think the way to go about this is - instead of embedding messages within another to log them both, simply log them side-by-side in different channels and make sure the logTime/publishTime are the same for each pair.