From e8781abc7f5f731366cd994e8a25dc89659c9fa7 Mon Sep 17 00:00:00 2001
From: Viktor Klang <viktor.klang@gmail.com>
Date: Tue, 26 May 2020 11:11:42 +0200
Subject: [PATCH] WIP of protocol changes to both accommodate Metadata but also
 clean up protocols

---
 protocols/protocol/cloudstate/crdt.proto      |  2 +
 protocols/protocol/cloudstate/entity.proto    | 54 ++++++++++++-------
 protocols/protocol/cloudstate/function.proto  |  9 ++--
 .../proto/cloudstate/proxy/statemanager.proto |  7 +--
 4 files changed, 41 insertions(+), 31 deletions(-)

diff --git a/protocols/protocol/cloudstate/crdt.proto b/protocols/protocol/cloudstate/crdt.proto
index 5c8135d78..b8b9ab42b 100644
--- a/protocols/protocol/cloudstate/crdt.proto
+++ b/protocols/protocol/cloudstate/crdt.proto
@@ -326,6 +326,8 @@ message CrdtReply {
     // and a CrdtStreamCancelled message will be sent if the stream is cancelled (though
     // not if the a CrdtStreamedMessage ends the stream first).
     bool streamed = 6;
+
+    repeated Metadata metadata = 7; // FIXME Should we rely on client_action Reply's metadata instead?
 }
 
 message CrdtStateAction {
diff --git a/protocols/protocol/cloudstate/entity.proto b/protocols/protocol/cloudstate/entity.proto
index 671b93826..aee8f37bf 100644
--- a/protocols/protocol/cloudstate/entity.proto
+++ b/protocols/protocol/cloudstate/entity.proto
@@ -31,16 +31,18 @@ option go_package = "cloudstate/protocol";
 message Reply {
     // The reply payload
     google.protobuf.Any payload = 1;
+
+    // The reply metadata
+    repeated Metadata metadata = 2;
 }
 
 // Forwards handling of this request to another entity.
 message Forward {
     // The name of the service to forward to.
     string service_name = 1;
-    // The name of the command.
-    string command_name = 2;
-    // The payload.
-    google.protobuf.Any payload = 3;
+
+    // The call to forward to that service
+    Call call = 2;
 }
 
 // An action for the client
@@ -64,15 +66,8 @@ message SideEffect {
     // The name of the service to perform the side effect on.
     string service_name = 1;
 
-    // The name of the command.
-    string command_name = 2;
-
-    // The payload of the command.
-    google.protobuf.Any payload = 3;
-
-    // Whether this side effect should be performed synchronously, ie, before the reply is eventually
-    // sent, or not.
-    bool synchronous = 4;
+    // The call to make on the service
+    Call call = 2;
 }
 
 // A command. For each command received, a reply must be sent with a matching command id.
@@ -81,17 +76,36 @@ message Command {
     // The ID of the entity.
     string entity_id = 1;
 
-    // A command id.
+    // A command identifier, to be used for correlation and deduplication purposes
     int64 id = 2;
 
-    // Command name
-    string name = 3;
+    // The Call to make on the entity
+    Call call = 3;
+}
+
+// A Call describes what endpoint, what payload, and what metadata to provide
+message Call {
+
+    // The name of the endpoint
+    string name = 1;
+
+    // The payload of the endpoint
+    google.protobuf.Any payload = 2;
+
+    // Whether or not to stream the response
+    bool streamed = 3;
+
+    // The metadata / headers to send with the call
+    repeated Metadata metadata = 4;
+}
 
-    // The command payload.
-    google.protobuf.Any payload = 4;
+// This Metadata construct should obey the exact same rules as traditional gRPC Metadata
+message Metadata {
+    // The name of this piece of metadata
+    string name = 1;
 
-    // Whether the command is streamed or not
-    bool streamed = 5;
+    // The value of the metadata
+    string value = 2;
 }
 
 message StreamCancelled {
diff --git a/protocols/protocol/cloudstate/function.proto b/protocols/protocol/cloudstate/function.proto
index d0e54ead5..827898b73 100644
--- a/protocols/protocol/cloudstate/function.proto
+++ b/protocols/protocol/cloudstate/function.proto
@@ -28,13 +28,10 @@ option go_package = "cloudstate/protocol";
 
 message FunctionCommand {
     // The name of the service this function is on.
-    string service_name = 2;
+    string service_name = 2; // TODO revisit this ordinal value
 
-    // Command name
-    string name = 3;
-
-    // The command payload.
-    google.protobuf.Any payload = 4;
+    // The call to make to that service
+    Call call = 5; // TODO revisit this ordinal value
 }
 
 message FunctionReply {
diff --git a/proxy/core/src/main/proto/cloudstate/proxy/statemanager.proto b/proxy/core/src/main/proto/cloudstate/proxy/statemanager.proto
index c75b4092c..d5bf6e0e4 100644
--- a/proxy/core/src/main/proto/cloudstate/proxy/statemanager.proto
+++ b/proxy/core/src/main/proto/cloudstate/proxy/statemanager.proto
@@ -30,15 +30,12 @@ option (scalapb.options) = {
 };
 
 message UserFunctionCommand {
-    string name = 1;
-    google.protobuf.Any payload = 2;
+    Call call = 1;
 }
 
 message EntityCommand {
     string entity_id = 1;
-    string name = 2;
-    google.protobuf.Any payload = 3;
-    bool streamed = 4;
+    Call call = 2;
 }
 
 message UserFunctionReply {