ServiceMonitor  - AS3

Whether the service is currently considered "available."

The initial value is false until either a status check sets the property to true or the property is initialized to true explicitly.

Typically, this property is set by the checkStatus() implementation in a subclass or specializer, but if the application has independent information about a service's availability (for example, a request just succeeded or failed), the property can be set explicitly.

The time of the last status update.

The interval, in milliseconds, for polling the server.

If zero, the server is not polled periodically, but only immediately after start() is called and when the network status changes.

The ServiceMonitor object only dispatches a status event if service status has changed (not on every poll interval). The object also dispatches a status event as a result of network connectivity changes (regardles of the poll interval).

The default value is 0.

Whether the monitor has been started.

Creates a ServiceMonitor object.

This class is typically subclassed to monitor specific service types.

After creating a ServiceMonitor object (or a subclass object), call the start() method to begin monitoring the status of the service.

As with the Timer object, the caller should maintain a reference to the ServiceMonitor object. Otherwise, the runtime deletes the object and monitoring ends.

Checks the status of the service.

A subclass override method for checking the status of the service.

Typically, this method will initiate a network operation whose completion or failure will result in setting the available property.

JavaScript code can specialize this method by defining a checkStatus() method in the "specializer" object.

Adds public ServiceMonitor methods to a JavaScript constructor function's prototype.

Adds functions to the JavaScript constructor function's prototype that forward public ServiceMonitor functions to the ServiceMonitor object. This approximates a normal JavaScript subclass of the ActionScript base class.

A JavaScript class specializing a ServiceMonitor would look like this:

     // JavaScript Constructor function
     function MyHTTPMonitor(url, method)
     {
         // "that" variable makes "this" available in closures below
         var that = this;
         // Required initialization of the service monitor, returns the actual ServiceMonitor object.
         this.monitor = this.initServiceMonitor();
         // Initializes URLStream and event handlers.
         this._urlStream = new air.URLStream();
         this._urlRequest = new air.URLRequest(url);
         if (method)
         {
             this._urlRequest.method = method;
         }
         else
         {
             this._urlRequest.method = "GET";
         }
         function onStatus(event) {
             that.monitor.available = Number(event.status) == 200;
             that._urlStream.close();
         }
         function onError(event)
         {
             that.monitor.available = false;
             that._urlStream.close();
         }
         this._urlStream.addEventListener(air.HTTPStatusEvent.HTTP_RESPONSE_STATUS, onStatus);
         this._urlStream.addEventListener(air.SecurityErrorEvent.SECURITY_ERROR, onError);
         this._urlStream.addEventListener(air.IOErrorEvent.IO_ERROR, onError);
     }
     
     // Augment JavaScript prototype with public methods from ServiceMonitor
     air.ServiceMonitor.makeJavascriptSubclass(MyHTTPMonitor);
     
     // Implement specializer functions, just as you would when subclassing a JavaScript class
     MyHTTPMonitor.prototype.checkStatus = function()
     {
         air.trace('OVERRIDDEN checkStatus!', this);
         this._urlStream.load(this._urlRequest);
     }
     

To use the JavaScript class:

     var httpMon = new MyHTTPMonitor('http://www.adobe.com')
     

Be sure to load the AIRAliases.js and aircore.swf files with script tags.

Parameters

Starts the service monitor.

Stops monitoring the service.

Returns the string representation of the specified object.

Note: Methods of the Object class are dynamically created on Object's prototype. To redefine this method in a subclass of Object, do not use the override keyword. For example, a subclass of Object implements function toString():String instead of using an override of the base class.

Indicates that the service status has changed.

The value of the code property is either "Service.available" or "Service.unavailable", but best practice is to check the value of the ServiceMonitor.available property.

This event has the following properties: