Server streaming case with an unary RPC does not create the streaming context

[BuddhiWathsala]

Description:

Case 01

Check the following proto definition.

syntax = "proto3";

import "google/protobuf/empty.proto";

service Store {
  rpc getAlbums(google.protobuf.Empty) returns (stream Album);
  rpc storeAlbum(Album) returns (Album);
}

message Album {
    string id = 1;
    string title = 2;
    string artist = 3;
    float price = 4;
};

When I generate the stub using CLI, the generated stub does not contain the ContextAlbumStream definition.

$ bal grpc --input record_store.proto
$ bal build temp/record_store_pb.bal        
Compiling source
        record_store_pb.bal
ERROR [record_store_pb.bal:(51:57,51:75)] unknown type 'ContextAlbumStream'
ERROR [record_store_pb.bal:(57:26,57:70)] incompatible types: expected 'other', found 'stream<Album,ballerina/grpc:1.2.0:Error?>'

Case 02

However, when I re-organize the RPCs as below (i.e., make server streaming as the second definition), it works fine.

syntax = "proto3";

import "google/protobuf/empty.proto";

service Store {
  rpc storeAlbum(Album) returns (Album);
  rpc getAlbums(google.protobuf.Empty) returns (stream Album); // Change the order
}

message Album {
    string id = 1;
    string title = 2;
    string artist = 3;
    float price = 4;
};

$ bal grpc --input record_store.proto
$ bal build temp/record_store_pb.bal        
Compiling source
        record_store_pb.bal

Generating executable
        record_store_pb.jar

The workaround to prevent this issue would be to re-organize RPCs as in Case 02.

Affected Versions:
SL GA

OS, DB, other environment details and versions:

• macOS
• Java 11