Generated .proto from CodeFirst service at runtime

[pengweiqhca]

[mgravell]

I'm going to infer a lot here, so... tell me if I'm wrong, but it sounds like you want there to exist some API akin to GetProto/GetSchema in protobuf-net that will allow you to obtain the .proto for a service (along with its dependent messages), via an API presumably originating with the type/types of the service-contracts, i.e.

string proto = Something.GetProto(typeof(IMyService));

is that correct? If so: this is already planned - needs a little work here, but shouldn't be too arduous.

[pengweiqhca]

Should be this, really looking forward to this.

[ChristianWeyer]

Hi @mgravell ,

are you still planning on adding this cool feature? ;-)
Thanks!

[mgravell]

Hi @ChristianWeyer - absolutely, yes; this is definitely something I want to do; the challenge is always competing demands for time, etc

[ChristianWeyer]

Great. Can we be of any help?

[mgravell]

In a way you already have been - I kinda rely on noise from people to prioritize, so knowing that more people are needing this helps. I have an unrelated pending PR on protobuf-net that changes (in a compatible way, obvs) the API shape of the schema generator API, so maybe this is a good time for me to try and do this. For clarity: is there any particular timescale /scenario / etc you're looking for here? And sample scenarios (test cases, effectively) are always helpful.

…

On Wed, 1 Jul 2020, 20:58 Christian Weyer, ***@***.***> wrote: Great. Can we be of any help? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#5 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAAEHMH7NVUW7UNI5BWUT33RZOINTANCNFSM4H3O777A> .

[ChristianWeyer]

Doing code-first with gRPC for e.g. Blazor WASM applications may indeed boost some parts of client dev productivity.
But then, for documentation, test tools, interop etc. we may still need the .protos.

So, while not having a hard timeline or even deadline - I Think having this feature would definitely help to make the story for client web dev with Blazor WASM and .NET Core backends a real nice story in terms of productivity.

What do you think?

[mgravell]

Total agreement; simply time (ultimately, this is one of several "evenings and weekends" things)
On the Blazor WASM front: that also ties in with the AOT plans via "generators", so we can prune the ref-emit code

[ChristianWeyer]

Awesome, then we agree ;-)

[jfalameda]

This is definitely a desirable feature for us. In our case, we use BloomRPC to test our endpoints (Postman for protobuf). Not having proto files makes it harder to develop and test. Also, as mentioned ^ up there, it makes it easy to integrate with other languages.

[mgravell]

OK; I have a first stab at the protobuf-net half of the code for this, in the "namespaces" branch; I have a plan to add the gRPC half of this into the new "reflection" package that is in #63 (probably adding the new csproj "now" rather than at merge) - the key thing being that right now I only plan to support this in v3 - IMO it is ok for the "reflection" package to have a hard v3 package reference, but the main lib should stay v2 for now. Example output:

syntax = "proto3";
package mypackage;
import "protobuf-net/protogen.proto"; // custom protobuf-net options
import "google/protobuf/timestamp.proto";
import "google/protobuf/duration.proto";
import "google/protobuf/empty.proto";

message Bar {
   string Value = 1;
}
message Foo {
   .google.protobuf.Timestamp When = 1;
   string Id = 2; // default value could not be applied: 00000000-0000-0000-0000-000000000000
   oneof subtype {
      option (.protobuf_net.oneofopt).isSubType = true;
      Bar Bar = 42;
   }
}
service myService {
   rpc unary (.google.protobuf.Timestamp) returns (.google.protobuf.Empty);
   rpc clientStreaming (Foo) returns (stream Foo);
   rpc serverStreaming (stream Foo) returns (.google.protobuf.Duration);
   rpc fullDuplex (stream Foo) returns (stream Foo);
}

Effectively, protobuf-net.Grpc would have the responsibility for preparing the service contract metadata, then calling into protobuf-net (which knows about data contract metadata).