Charles Petzold Networking

Agenda WebClient HttpWebRequest Consuming REST services Consuming ASMX and WCF services Push notification services Tile scheduling

Silverlight vs. SWP FeatureSilverlightSWP Cross-domain networking Requires elevated permissions or policy file No restrictions Cross-protocol networking Requires elevated permissions or policy file No restrictions Networking stacks Browser stack and client stackClient stack only Duplex networking PollingDuplexHttpBinding and NetTcpBinding HttpNotificationChannel Authentication Basic, digest, NTLM, and formsBasic and forms Sockets YesNot supported UDP multicasting YesNot supported

Event-based HTTP networking API –Asynchronous operation only Commonly used to download assets –DownloadStringAsync - String –OpenReadAsync – Stream (binary) –Also features uploading methods Fires progress and completion events and supports cancellation of pending requests –Event handlers execute on calling thread WebClient

Downloading an Image File WebClient wc = new WebClient(); wc.OpenReadCompleted += new OpenReadCompletedEventHandler(OnOpenReadCompleted); wc.OpenReadAsync(new Uri (" private void OnOpenReadCompleted(object sender, OpenReadCompletedEventArgs e) { if (e.Error == null) { BitmapImage bi = new BitmapImage(); bi.SetSource(e.Result); MyImage.Source = bi; }

Downloading a Zipped Image File WebClient wc = new WebClient(); wc.OpenReadCompleted += new OpenReadCompletedEventHandler(OnOpenReadCompleted); wc.OpenReadAsync(new Uri(" private void OnOpenReadCompleted(object sender, OpenReadCompletedEventArgs e) { if (e.Error == null) { StreamResourceInfo sri1 = new StreamResourceInfo(e.Result, null); StreamResourceInfo sri2 = Application.GetResourceStream(sri1, new Uri("Bandit.jpg", UriKind.Relative)); BitmapImage bi = new BitmapImage(); bi.SetSource(sri2.Stream); MyImage.Source = bi; }

Updating a Progress Bar WebClient wc = new WebClient(); wc.DownloadProgressChanged += OnDownloadProgressChanged;... private void OnDownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e) { Progress.Value = e.ProgressPercentage; }

Downloading an RSS Feed WebClient wc = new WebClient(); wc.OpenReadCompleted += new OpenReadCompletedEventHandler(OnOpenReadCompleted); wc.OpenReadAsync(new Uri("..."));... private void OnOpenReadCompleted(object sender, OpenReadCompletedEventArgs e) { if (e.Error == null) { using (StreamReader reader = new StreamReader(e.Result)) { string rss = reader.ReadToEnd(); // TODO: Parse the feed }

demo WebClient

Delegate-based HTTP networking API –Asynchronous operation only Generally used to call untyped HTTP services –e.g., REST services Completion methods called on background threads from CLR thread pool –Use Dispatcher.BeginInvoke to update UI HttpWebRequest

Calling a REST Service (GET) HttpWebRequest request = (HttpWebRequest) HttpWebRequest.Create (new Uri(" request.BeginGetResponse (new AsyncCallback(OnGetResponseCompleted), request);... private void OnGetResponseCompleted(IAsyncResult ar) { HttpWebRequest request = (HttpWebRequest)ar.AsyncState; HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(ar); using (StreamReader reader = new StreamReader(response.GetResponseStream())) { string result = reader.ReadToEnd();... }

Calling a REST Service (POST) HttpWebRequest request = (HttpWebRequest) HttpWebRequest.Create (new Uri(" request.Method = "POST"; request.ContentType = "application/x-www-form-urlencoded"; request.BeginGetRequestStream(new AsyncCallback (OnGetRequestStreamCompleted), request);... private void OnGetRequestStreamCompleted(IAsyncResult ar) { HttpWebRequest request = (HttpWebRequest)ar.AsyncState; using (StreamWriter writer = new StreamWriter(request.EndGetRequestStream(ar))) { writer.Write("98052"); // Write input into body of request } request.BeginGetResponse(new AsyncCallback(OnGetResponseCompleted), request); }... private void OnGetResponseCompleted(IAsyncResult ar) {... }

demo HttpWebRequest

Callable through WCF Web service proxies –Use Visual Studio's "Add Service Reference" command to generate proxies Selected WCF bindings supported –BasicHttpBinding (WS-I Basic Profile 1.0) –Custom HTTP binding with binary message encoding –No PollingDuplexHttpBinding or NetTcpBinding Asynchronous operation only ASMX and WCF Services

Use "Add New Item" -> "Silverlight-Enabled WCF Service" command in Visual Studio Creating a WCF Service

Calling a WCF Service ZipCodeServiceClient proxy = new ZipCodeServiceClient(); proxy.GetCityAndStateFromZipCodeCompleted += new EventHandler (GetCityAndStateFromZipCodeCompleted); proxy.GetCityAndStateFromZipCodeAsync("98052");... private void GetCityAndStateFromZipCodeCompleted(object sender, GetCityAndStateFromZipCodeCompletedEventArgs e) { if (e.Error == null) { Place place = e.Result; // Method returns Place object string city = place.City; string state = place.State;... }

demo WCF Services

Asynchronous notifications delivered to phones Utilize Microsoft Push Notification Service (PNS) –Hosted in Azure; massively scalable and reliable –Battery- and bandwidth-efficient alternative to polling Three types of notifications –Raw notifications –Toast notifications –Tile notifications Toast and tile notifications work if app isn't running Push Notifications

How Push Notifications Work Microsoft Push Notification Service Your Web Service Count 3 4 Phone transmits URI to Web service Service calls PNS using transmitted URI PNS sends notification to phone PNS returns URI Phone app requests URI from PNS

Delivered only when app is active –If app is inactive, call to PNS returns HTTP 200 OK with notification status == "Suppressed" Payload can be text or binary data –1K maximum payload size Raw Notifications

Raw Notification Wire Format POST uri HTTP/1.1 X-NotificationClass: interval Host: uri Content-Type: application/*; charset=UTF-8 Content-Length: length payload

Sending a Raw Notification HttpWebRequest request = HttpWebRequest.Create(uri) as HttpWebRequest; request.Method = WebRequestMethods.Http.Post; request.Headers.Add("X-NotificationClass", "3"); // Send immediately using (Stream stream = request.GetRequestStream()) { byte[] payload = Encoding.UTF8.GetBytes(message); stream.Write(payload, 0, payload.Length); } HttpWebResponse response = request.GetResponse() as HttpWebResponse;

Delivered even when application is inactive –Displayed in toast window at top of screen –Clicking toast window activates application Also delivered when application is active –Not automatically displayed –App decides what to do Toast Notifications

Toast Notification Wire Format POST uri HTTP/1.1 X-NotificationClass: interval X-WindowsPhone-Target: toast Host: uri Content-Type: application/*; charset=UTF-8 Content-Length: length MessageCaption MessageText

Sending a Toast Notification HttpWebRequest request = HttpWebRequest.Create(uri) as HttpWebRequest; request.Method = WebRequestMethods.Http.Post; request.ContentType = "text/xml"; request.Headers["X-WindowsPhone-Target"] = "toast"; request.Headers.Add("X-NotificationClass", "2"); // Send immediately using (Stream stream = request.GetRequestStream()) { byte[] payload = Encoding.UTF8.GetBytes (String.Format(_template, caption, message)); request.ContentLength = payload.Length; stream.Write(payload, 0, payload.Length); } HttpWebResponse response = request.GetResponse() as HttpWebResponse;

Update tiles pinned on start screen ("live tiles") –Change tile background image Local or remote images Max size 80K; must load in under 15 seconds –Change count displayed in tile's upper-right corner –Change title displayed along tile's bottom border Tile Notifications Title Count

Tile Notification Wire Format POST uri HTTP/1.1 X-NotificationClass: interval X-WindowsPhone-Target: tile Host: uri Content-Type: application/*; charset=UTF-8 Content-Length: length BackgroundImageUri Count Title

Sending a Tile Notification HttpWebRequest request = HttpWebRequest.Create(uri) as HttpWebRequest; request.Method = WebRequestMethods.Http.Post; request.ContentType = "text/xml"; request.Headers["X-WindowsPhone-Target"] = "token"; request.Headers.Add("X-NotificationClass", "1"); // Send immediately using (Stream stream = request.GetRequestStream()) { byte[] payload = Encoding.UTF8.GetBytes (String.Format(_template, imageuri, count, title)) request.ContentLength = payload.Length; stream.Write(payload, 0, payload.Length); } HttpWebResponse response = request.GetResponse() as HttpWebResponse;

Calls to PNS return important information in HTTP status codes and custom response headers –X-NotificationStatus –X-SubscriptionStatus –X-DeviceConnectionStatus Certain response codes must not be ignored –Subscription may be expired –Subscription may require server-side throttling Response codes documented at PNS Response Codes

Sample Response Codes HTTP Status Notification Status Subscription Status Device Status Comments 200ReceivedActiveConnectedNotification was accepted 200ReceivedActiveTempDisconnected Notification was accepted, but device is disconnected 200QueueFullActiveAny value Notification queue is full; try again later 200SuppressedActiveAny value Notification could not be delivered because application is not active 404Any value Expired Subscription has expired and should be deleted; do not resend 406Any value Per-day quota has been reached; can try to resend once per hour 412Any value Device is inactive; can try to resend once per hour, but with penalties 503Any value PNS is unavailable

Handling Response Codes HttpWebResponse response = request.GetResponse() as HttpWebResponse; int status = (int)response.StatusCode; string xsubscription = null; if (response.Headers["X-SubscriptionStatus"] != null) xsubscription = response.Headers["X-SubscriptionStatus"].ToString(); if ((xsubscription != null && xsubscription == "Expired") || status == 404 || status == 406 || status == 412) { // Delete the subscription RemoveSubscription(uri); }

Class used to connect phone apps to PNS HttpNotificationChannel MethodDescription BindToShellTile Binds channel to tile notifications BindToShellToast Binds channel to toast notifications Close Close an open channel Find Returns an existing channel if that channel exists Open Opens a channel UnbindToShellTile Unbinds channel to tile notifications UnbindToShellToast Unbinds channel to toast notifications

Opening a Channel channel = HttpNotificationChannel.Find("MyChannel"); if (channel == null) // Create a new channel { channel = new HttpNotificationChannel("MyChannel"); RegisterChannelEventHandlers(channel); channel.Open(); // Generates ChannelUriUpdated event } else // Configure an existing channel { RegisterChannelEventHandlers(channel); BindChannel(channel); // TODO: Send the URI to the Web service }

Binding to Notifications // Configure the channel to report toast notifications if (!channel.IsShellToastBound) channel.BindToShellToast(); // Configure the channel to support tile notifications if (!channel.IsShellTileBound) channel.BindToShellTile();

Handling Raw Notifications channel.HttpNotificationReceived += OnRawNotificationReceived;. void OnHttpNotificationReceived(object sender, HttpNotificationEventArgs e) { // Transfer to UI thread if updating the UI Dispatcher.BeginInvoke(() => { // Payload in e.Notification.Body }); }

Handling Toast Notifications channel.ShellToastNotificationReceived += OnToastReceived;... void OnToastReceived(object sender, NotificationEventArgs e) { // Transfer to UI thread if updating the UI Dispatcher.BeginInvoke(() => { string caption = String.Empty; if (e.Collection.ContainsKey("wp:Text1")) caption = e.Collection["wp:Text1"]; string message = String.Empty; if (e.Collection.ContainsKey("wp:Text2")) message = e.Collection["wp:Text2"];... }); }

Handling Tile Notifications This space intentionally left blank

Limit of one open channel per app Limit of 15 open channels per device –No way to know ahead of time how many are open –HttpNotificationChannel.Open throws InvalidOperationException when limit is exceeded Limit of 500 notifications per day per channel –Limit waived for authenticated Web services Apps that use push notifications must comply with WP7 Application Certification Requirements Constraints and Limitations

demo Push Notifications

ShellTileSchedule class permits tiles to be updated periodically by downloading them from a server –Does not count against push notification limit –Frequency cannot exceed one update per hour Options are hourly, daily, weekly, monthly –Max image size 80K; must load in < 15 seconds Updates suspended when screen is locked or off –Updates fire immediately when screen unlocks Tile Scheduling

Scheduling Hourly Updates ShellTileSchedule sts = new ShellTileSchedule(); sts.Interval = UpdateInterval.EveryHour; sts.MaxUpdateCount = 0; // Run indefinitely sts.Recurrence = UpdateRecurrence.Interval; sts.RemoteImageUri = new sts.Start();

Performing a One-Time Update xShellTileSchedule sts = new ShellTileSchedule(); sts.Recurrence = UpdateRecurrence.OneTime; sts.StartTime = DateTime.Now; sts.RemoteImageUri = new sts.Start();

Detecting Connectivity Status if (NetworkInterface.GetIsNetworkAvailable()) { // App is connected } else { // App is not connected }

Detecting Status Changes NetworkChange.NetworkAddressChanged += OnNetworkAddressChanged;. void OnNetworkAddressChanged(object sender, EventArgs e) { if (NetworkInterface.GetIsNetworkAvailable()) { // App is connected } else { // App is not connected }

Charles Petzold Questions?