ActionServer updates

* Add action.start to make rosnodejs' ActionServer compatible with ActionClient in python & C++
* Publishes action status at statusFrequency

Author: mjyc

README.md

@@ -96,11 +96,13 @@ const as = new rosnodejs.ActionServer({
   actionServer: '/turtle_shape'
 });
 
-as.on('goal, function (goal) {
+as.on('goal', function (goal) {
   goal.setAccepted();
 });
 
-const ac = nh.actionClientInterface('/turtle_shape, 'turtle_actionlib/ShapeAction');
+as.start();
+
+const ac = nh.actionClientInterface('/turtle_shape', 'turtle_actionlib/ShapeAction');
 ac.sendGoal({ goal: {edges: 3, radius: 1}});
 ```
 ## Run the turtlesim example

src/actions/ActionServer.js

@@ -73,14 +73,24 @@ class ActionServer extends EventEmitter {
 
     this._lastCancelStamp = timeUtils.epoch();
 
+    this._statusFrequency = 5;
     this._statusListTimeout = 5;
+    this._statusHandle = null;
+
+    this._started = false;
   }
 
   generateGoalId() {
     return this._asInterface.generateGoalId();
   }
 
+  start() {
+    this._started = true;
+    this._statusHandle = setInterval(this.publishStatus.bind(this), 1000 / this._statusFrequency);
+  }
+
   shutdown() {
+    clearInterval(this._statusHandle);
     return this._asInterface.shutdown();
   }
 
@@ -89,6 +99,10 @@ class ActionServer extends EventEmitter {
   }
 
   _handleGoal(msg) {
+    if (!this._started) {
+      return;
+    }
+
     const newGoalId = msg.goal_id.id;
 
     let handle = this._getGoalHandle(newGoalId);
@@ -123,6 +137,10 @@ class ActionServer extends EventEmitter {
   }
 
   _handleCancel(msg) {
+    if (!this._started) {
+      return;
+    }
+
     const cancelId = msg.id;
     const cancelStamp = msg.stamp;
     const cancelStampIsZero = timeUtils.isZeroTime(cancelStamp);