Miglioramento: coda WebSocket e servizio Linux

RESTserver/LEGGIMI.md

@@ -35,6 +35,7 @@ La latenza media (ritardo) tra un evento e la sua segnalazione in un client WEB
 
 3. **Configurazione:**
     * Aggiorna il tuo percorso di installazione nel file `run_server.bat`
+    * Per gli utenti Linux/Raspberry Pi, è fornito il file `iotwebui.service` per l'avvio automatico tramite systemd.
 
 4. **Test e debug**
 Ci sono tre file principali:

RESTserver/README.md

@@ -33,6 +33,7 @@ The average latency (delay) between an event and its reporting in a WEB client u
     * Click on `install_server.bat`: it will install the updated dependencies in the 'node_modules' dir.
 3. **Configuration:**
     * Update your installation path in the `run_server.bat` file
+    * For Linux/Raspberry Pi users, a `iotwebui.service` file is provided for autostart functionality via systemd. 
 4. **Testing and debugging**
 There are three main files:
     * `server.js`: the executable file with the IoTrest implementation, to be launched in a terminal or using `run_server.bat`.

RESTserver/iotwebui.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=IoTwebUI REST Server
+After=network.target
+
+[Service]
+Type=simple
+# Update the path to your actual installation directory
+WorkingDirectory=/opt/IoTwebUI/RESTserver
+ExecStart=/usr/bin/node server.js
+Restart=on-failure
+RestartSec=5
+User=pi
+
+[Install]
+WantedBy=multi-user.target

RESTserver/server.js

@@ -45,18 +45,40 @@ let connectedClient = null;
   });
 });
 
-// Improved getAnswer function using async/await
+// Improved getAnswer function using queue to solve race conditions on multi-requests
+let requestQueue = [];
+let isFetching = false;
+
 async function getAnswer(message) {
   if (!connectedClient) {
     throw new Error('No connected client');
   }
-  connectedClient.send(message); // Send the request message
 
   return new Promise((resolve, reject) => {
-    connectedClient.onmessage = ({ data }) => {
-      resolve(data);
-    };
-   });
+    requestQueue.push({ message, resolve, reject });
+    processQueue();
+  });
+}
+
+function processQueue() {
+  if (isFetching || requestQueue.length === 0 || !connectedClient) return;
+
+  isFetching = true;
+  const task = requestQueue.shift();
+
+  connectedClient.onmessage = ({ data }) => {
+    isFetching = false;
+    task.resolve(data);
+    processQueue(); 
+  };
+
+  try {
+     connectedClient.send(task.message);
+  } catch(e) {
+     isFetching = false;
+     task.reject(e);
+     processQueue();
+  }
 }
 
 // Define HAPI route for fetching all data