Replace gRPC Backend (#10)

**Rationale:**

Having two separate servers and communication methods resulted in additional maintenance & the need to convert often between backend & frontend data types.
By moving the backend communication off of gRPC and to just use websockets it both gives more control & allows for simplification of the implementation.

#8

**Changes:**

- Replaces gRPC backend.
  - New implementation automatically handles reconnect logic
- Implements an api layer
- Migrates examples to the api layer
- Implements a proc macro to make command handling easier
- Implements unit tests for the api layer (90+% coverage)
- Implements integration tests for the proc macro (90+% coverage)

Reviewed-on: #10
Co-authored-by: Sergey Savelyev <sergeysav.nn@gmail.com>
Co-committed-by: Sergey Savelyev <sergeysav.nn@gmail.com>

server/src/http/websocket/mod.rs

@@ -6,6 +6,7 @@ use crate::telemetry::management_service::TelemetryManagementService;
 use actix_web::{rt, web, HttpRequest, HttpResponse};
 use actix_ws::{AggregatedMessage, ProtocolError, Session};
 use anyhow::anyhow;
+use futures_util::StreamExt;
 use log::{error, trace};
 use std::collections::HashMap;
 use std::sync::Arc;
@@ -14,7 +15,7 @@ use tokio::select;
 use tokio::sync::mpsc::Sender;
 use tokio::time::{sleep_until, Instant};
 use tokio_util::sync::CancellationToken;
-use tonic::codegen::tokio_stream::StreamExt;
+use uuid::Uuid;
 
 pub mod request;
 pub mod response;
@@ -23,11 +24,11 @@ fn handle_register_tlm_listener(
     data: &Arc<TelemetryManagementService>,
     request: RegisterTlmListenerRequest,
     tx: &Sender<WebsocketResponse>,
-    tlm_listeners: &mut HashMap<String, CancellationToken>,
+    tlm_listeners: &mut HashMap<Uuid, CancellationToken>,
 ) {
     if let Some(tlm_data) = data.get_by_uuid(&request.uuid) {
         let token = CancellationToken::new();
-        if let Some(token) = tlm_listeners.insert(tlm_data.definition.uuid.clone(), token.clone()) {
+        if let Some(token) = tlm_listeners.insert(tlm_data.definition.uuid, token.clone()) {
             token.cancel();
         }
         let minimum_separation = Duration::from_millis(request.minimum_separation_ms as u64);
@@ -46,7 +47,7 @@ fn handle_register_tlm_listener(
                             ref_val.clone()
                         };
                         let _ = tx.send(TlmValueResponse {
-                            uuid: request.uuid.clone(),
+                            uuid: request.uuid,
                             value,
                         }.into()).await;
                         now
@@ -65,7 +66,7 @@ fn handle_register_tlm_listener(
 
 fn handle_unregister_tlm_listener(
     request: UnregisterTlmListenerRequest,
-    tlm_listeners: &mut HashMap<String, CancellationToken>,
+    tlm_listeners: &mut HashMap<Uuid, CancellationToken>,
 ) {
     if let Some(token) = tlm_listeners.remove(&request.uuid) {
         token.cancel();
@@ -76,7 +77,7 @@ async fn handle_websocket_message(
     data: &Arc<TelemetryManagementService>,
     request: WebsocketRequest,
     tx: &Sender<WebsocketResponse>,
-    tlm_listeners: &mut HashMap<String, CancellationToken>,
+    tlm_listeners: &mut HashMap<Uuid, CancellationToken>,
 ) {
     match request {
         WebsocketRequest::RegisterTlmListener(request) => {
@@ -110,7 +111,7 @@ async fn handle_websocket_incoming(
     data: &Arc<TelemetryManagementService>,
     session: &mut Session,
     tx: &Sender<WebsocketResponse>,
-    tlm_listeners: &mut HashMap<String, CancellationToken>,
+    tlm_listeners: &mut HashMap<Uuid, CancellationToken>,
 ) -> anyhow::Result<bool> {
     match msg {
         Ok(AggregatedMessage::Close(_)) => Ok(false),
@@ -130,7 +131,7 @@ async fn handle_websocket_incoming(
     }
 }
 
-pub async fn websocket_connect(
+async fn websocket_connect(
     req: HttpRequest,
     stream: web::Payload,
     data: web::Data<Arc<TelemetryManagementService>>,

server/src/http/websocket/request.rs

@@ -1,15 +1,16 @@
 use derive_more::From;
 use serde::{Deserialize, Serialize};
+use uuid::Uuid;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct RegisterTlmListenerRequest {
-    pub uuid: String,
+    pub uuid: Uuid,
     pub minimum_separation_ms: u32,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct UnregisterTlmListenerRequest {
-    pub uuid: String,
+    pub uuid: Uuid,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, From)]

server/src/http/websocket/response.rs

@@ -1,10 +1,11 @@
 use crate::telemetry::data_item::TelemetryDataItem;
 use derive_more::From;
 use serde::{Deserialize, Serialize};
+use uuid::Uuid;
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct TlmValueResponse {
-    pub uuid: String,
+    pub uuid: Uuid,
     pub value: Option<TelemetryDataItem>,
 }