gRPC / Protobuf interface versioning

Question

Let\'s say we use gRCP/Protobuf to connect many application. Those application are developped and released at their own team, with their own speed. Over time there will be d

Answer 1

In the upcoming versions of gRPC, there will be a new feature called Server Reflection. This will allow a client to ask the server for the Descriptors that descriptor the proto file being used. Rather than the server knowing about the version the client is running, the client will know what the server is running. If the server descriptor matches the one the client already has, then it will know that they are speaking at the same version.

This will be released in version 1.1.

Note that Protobufs are designed so that you don't have to do this! If you set up your proto correctly, old and new versions of clients and server should work together.

Answer 2

One way to do this would be to add a custom option and set that option at the top of your .proto file, like this:

option (my_app.version) = 3;

Then in each language you can examine the value of that option and indicate it as your version number.

Answer 3

If you are using protocol buffers version 2, you can use the default values to implement this. Protocol buffers 3 has removed support for default values so this answer doesn't work there.

In the .proto file defining your interface, have something like:

message MyLoginMessage
{
    ... normal login fields ...

    // Increment this number when you make new releases
    // of this .proto.
    optional int32 protocol_version [default=55];
}

This way any client will automatically include the version number taken from the .proto.

Edit: Ah, just noticed the proto3 tag.. so I guess this answer is not useful to you after all.