Add comms module

public/red/comms.js

@@ -0,0 +1,61 @@
+/**
+ * Copyright 2014 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ **/
+ 
+RED.comms = function() {
+    
+    var errornotification = null;
+    var subscriptions = {};
+    
+    function connectWS() {
+        var path = location.hostname+":"+location.port+document.location.pathname;
+        path = path+(path.slice(-1) == "/"?"":"/")+"comms";
+        path = "ws"+(document.location.protocol=="https:"?"s":"")+"://"+path;
+        var ws = new WebSocket(path);
+        ws.onopen = function() {
+            if (errornotification) {
+                errornotification.close();
+                errornotification = null;
+            }
+        }
+        ws.onmessage = function(event) {
+            var msg = JSON.parse(event.data);
+            var subscribers = subscriptions[msg.topic];
+            if (subscribers) {
+                for (var i=0;i<subscribers.length;i++) {
+                    subscribers[i](msg.topic,msg.data);
+                }
+            }
+        };
+        ws.onclose = function() {
+            if (errornotification == null) {
+                errornotification = RED.notify("<b>Error</b>: Lost connection to server","error",true);
+            }
+            setTimeout(connectWS,1000);
+        }
+    }
+    connectWS();
+
+    function subscribe(topic,callback) {
+        if (subscriptions[topic] == null) {
+            subscriptions[topic] = [];
+        }
+        subscriptions[topic].push(callback);
+    }
+    
+    return {
+        subscribe: subscribe
+    }
+}();