Adding ping-pong. Fixes #71

service/src/main/java/com/simplevote/webservice/PollWebSocket.java

@@ -5,7 +5,6 @@
  */
 
 import ch.qos.logback.classic.Logger;
-import com.auth0.jwt.interfaces.DecodedJWT;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import com.simplevote.db.Actions;
@@ -20,7 +19,6 @@
 import org.javalite.activejdbc.LazyList;
 import org.slf4j.LoggerFactory;
 
-import java.io.IOException;
 import java.text.ParseException;
 import java.util.*;
 import java.util.stream.Collectors;
@@ -36,10 +34,12 @@ public class PollWebSocket {
   // A map with the user to their poll id
   private static Map<User, Long> userPollMap = new HashMap<>();
 
+  private static final Integer PING_DELAY = 10000;
+
   enum MessageType {
     poll, pollComments, pollUsers, pollActiveUsers, pollQuestions, pollCandidates, pollVotes, updatePoll, deletePoll,
     createComment, deleteComment, createQuestion, deleteQuestion, updateQuestion, createCandidate, deleteCandidate,
-    updateCandidate, createOrUpdateVote, deleteVote;
+    updateCandidate, createOrUpdateVote, deleteVote, Ping, Pong;
   }
 
   @OnWebSocketConnect
@@ -50,6 +50,8 @@ public void onConnect(Session session) throws Exception {
     Long pollId = getPollIdFromSession(session);
     sessionPollMap.put(session, pollId);
 
+    sendRecurringPings(session);
+
     // Send the poll
     sendMessage(session, messageWrapper(MessageType.poll, Actions.getPoll(pollId).toJson(false)));
 
@@ -127,7 +129,9 @@ public void onMessage(Session session, String dataStr) {
       case deleteVote:
         deleteVote(session, data);
         break;
-
+      case Pong:
+        pongReceived(session, data);
+        break;
       }
 
     } catch (Exception e) {
@@ -296,6 +300,27 @@ public void deleteVote(Session session, JsonNode data) {
 
   }
 
+  private void sendRecurringPings(Session session) {
+    final Timer timer = new Timer();
+    final TimerTask tt = new TimerTask() {
+      @Override
+      public void run() {
+        if (session.isOpen()) {
+          sendMessage(session, messageWrapper(MessageType.Ping, "{}"));
+        } else {
+          timer.cancel();
+          timer.purge();
+        }
+      }
+    };
+
+    timer.scheduleAtFixedRate(tt, PING_DELAY, PING_DELAY);
+  }
+
+  private void pongReceived(Session session, JsonNode data) {
+    log.debug("Pong received from " + session.getRemoteAddress());
+  }
+
   private static String messageWrapper(MessageType type, String data) {
     return "{\"message_type\":" + type.ordinal() + ",\"data\":" + data + "}";
   }

ui/src/app/components/poll/poll.component.ts

@@ -45,7 +45,7 @@ export class PollComponent implements OnInit {
 	public isLoading: boolean = false;
 	private initEditing: boolean = false;
 
-	private reconnnectTimeWaitMS: number = 60000;
+	private reconnnectTimeWaitMS: number = 10000;
 
 	@ViewChild('reconnectModal') private reconnectModal: ModalDirective;
 
@@ -188,8 +188,9 @@ export class PollComponent implements OnInit {
 			case MessageType.deleteVote:
 				this.receiveDeleteVote(msg.data);
 				break;
-
-
+			case MessageType.Ping:
+				this.sendPong();
+				break;
 			default:
 				alert('wrong message: ' + dataStr);
 		}
@@ -468,6 +469,12 @@ export class PollComponent implements OnInit {
 		this.poll.comments.splice(commentIndex, 1);
 	}
 
+	sendPong() {
+		console.debug("Received ping, sending pong");
+		this.pollService.send(Tools.messageWrapper(MessageType.Pong,
+			{}));
+	}
+
 	exportPoll() {
 		let pollJson: string = JSON.stringify(this.poll, null, 2);
 

ui/src/app/shared/message-type.enum.ts

@@ -6,5 +6,6 @@ export enum MessageType {
 	createComment, deleteComment,
 	createQuestion, deleteQuestion, updateQuestion,
 	createCandidate, deleteCandidate, updateCandidate,
-	createOrUpdateVote, deleteVote
+	createOrUpdateVote, deleteVote,
+	Ping, Pong
 }