*: add gRPC server for interacting with storages

api/apipb/api.proto

@@ -0,0 +1,74 @@
+syntax = "proto3";
+
+// Run `make grpc` at the top level directory to regenerate Go source code.
+
+package apipb;
+
+message Client {
+  string id = 1;
+  string secret = 2;
+
+  repeated string redirect_uris = 3;
+  repeated string trusted_peers = 4;
+
+  bool public = 5; 
+
+  string name = 6;
+  string logo_url = 7;
+}
+
+message CreateClientReq {
+  Client client = 1;
+}
+
+message CreateClientResp {
+  Client client = 1;
+}
+
+message UpdateClientReq {
+  string id = 1;
+
+  // Empty strings indicate that string fields should not be updated.
+  string secret = 2;
+  string name = 3;
+  string logo_url = 4;
+
+  bool make_public = 5;
+  bool make_private = 6;
+
+  // If no redirect URIs are specified, the current redirect URIs are preserved.
+  repeated string redirect_uris = 7;
+}
+
+message UpdateClientResp {
+  Client client = 1;
+}
+
+message ListClientsReq {
+}
+
+message ListClientsResp {
+  repeated Client clients = 1;
+}
+
+message DeleteClientReq {
+  string id = 1;
+}
+
+message DeleteClientResp {}
+
+message GetClientReq {
+  string id = 1;
+}
+
+message GetClientResp {
+  Client client = 1;
+}
+
+service Storage {
+  rpc CreateClient(CreateClientReq) returns (CreateClientResp) {}
+  rpc DeleteClient(DeleteClientReq) returns (DeleteClientReq) {}
+  rpc GetClient(GetClientReq) returns (GetClientResp) {}
+  rpc ListClients(ListClientsReq) returns (ListClientsResp) {}
+  rpc UpdateClient(UpdateClientReq) returns (UpdateClientResp) {}
+}