Implement UnSubscribe

lib/src/session.dart

@@ -32,6 +32,7 @@ class Session {
   final Map<int, Completer<Published>> publishRequests = {};
   final Map<int, SubscribeRequest> subscribeRequests = {};
   final Map<int, void Function(Event)> subscriptions = {};
+  final Map<int, UnsubscribeRequest> unsubscribeRequests = {};
 
   void processIncomingMessage(Message msg) {
     if (msg is Result) {
@@ -74,6 +75,12 @@ class Session {
       if (endpoint != null) {
         endpoint(msg);
       }
+    } else if (msg is UnSubscribed) {
+      var request = unsubscribeRequests.remove(msg.requestID);
+      if (request != null) {
+        subscriptions.remove(request.subscriptionId);
+        request.future.complete();
+      }
     }
   }
 
@@ -143,4 +150,14 @@ class Session {
 
     return completer.future;
   }
+
+  Future<void> unsubscribe(Subscription sub) {
+    var unsubscribe = UnSubscribe(nextID, sub.subscriptionId);
+
+    var completer = Completer<void>();
+    unsubscribeRequests[unsubscribe.requestID] = UnsubscribeRequest(completer, sub.subscriptionId);
+    baseSession.send(wampSession.sendMessage(unsubscribe));
+
+    return completer.future;
+  }
 }

lib/src/types.dart

@@ -58,3 +58,10 @@ class SubscribeRequest {
   final Completer<Subscription> future;
   final void Function(Event) endpoint;
 }
+
+class UnsubscribeRequest {
+  UnsubscribeRequest(this.future, this.subscriptionId);
+
+  final Completer<void> future;
+  final int subscriptionId;
+}