feat(client): Send ws message periodically

Fix #5

assets/run_info/run_info.js

@@ -25,6 +25,14 @@ const ws = new WebSocket(protocol + "//" + loc.host + loc.pathname + "/../ws");
 
 ws.onopen = function () {
  document.getElementById("downloadButton").disabled = false;
+
+ // If server is running behind a reverse proxy, the WebSocket connection may
+ // be terminated after a period of inactivity. Keep the connection alive by
+ // sending a ping message every 30 seconds.
+ const pingInterval = 30 * 1000;
+ setInterval(function () {
+ ws.send(JSON.stringify({ service: "Heartbeat" }));
+ }, pingInterval);
 };
 
 // The WebSocket connection is closed when the page is unloaded. In this case,