Presented by Gill Cleeren.

1. Windows 8 apps
and the outside world
Gill Cleeren
Microsoft Regional Director & MVP
Telerik MVP

2. About myself...
• Gill Cleeren
• .NET Architect @Ordina (www.ordina.be)
• Microsoft Regional Director
• Silverlight MVP
• Speaker (TechDays, TechEd, DevReach, DevDays, NDC Norway, Telerik
Usergroup tours...)
• Visug user group lead (www.visug.be)
• Author:
• Silverlight 4 Data and services cookbook
• Silverlight 5 Data and services cookbook
• Blog: www.snowball.be
• Email: gill@snowball.be
• Twitter: @gillcleeren

3. Silverlight 5 Data and Services
Cookbook available!
• Updated for Silverlight 5
• Over 115 recipes (that’s 30 extra!)
• Extended to about 700 pages
• (That’s 250 extra!)
• Covering WP7, MVVM,
RIA Services and much more!
• More info:
http://bit.ly/SL5DataAndServices

4. Agenda
• Accessing data behind a service
• Working with WCF and ASMX services
• Working with REST services
• Accessing oData services
• Syndication with RSS
• Background transfers
• Tiles interactions
• Periodic tile updates
• Push notifications
• Authenticating with Twitter and Facebook using the WebAuthBroker
• Using the Live SDK in your Windows 8 apps
• Using roaming data in your applications
• Working with sockets
• TCP sockets
• WebSockets

5. What we aren’t covering today
• ControlChannelTrigger
• Raw notifications
• Azure

6. Accessing data behind
a service

7. Working with services to access
data
• Service communication is always done asynchronous
• In Silverlight, this was done using a callback
• In C#5, we got the async/await keywords
• Fully supported in Metro/WinRT development
• await keyword makes things easier
• Doesn’t block UI thread
• Doesn’t require the ugly
Dispatcher.BeginInvoke(() => …);
• Getting data in a Metro application is a 3-step process
• Calling the service asynchronous
• Receiving and parsing the data
• Using the data, for example in a data-binding scenario

8. Working with services to access
data
• Working with services is preferred in most cases
• Relational databases should be behind a service
• Local app storage
• App has its own storage directory
• Can access local file system
• Not the focus of this talk!

9. Working with services
• Windows 8 supports all kinds of services
• ASMX
• WCF
• REST (JSON or XML)
• RSS (later in this talk)
• Sockets (much later in this talk)
• oData services (you get the drill, it’s also further in this
talk…)
• No WCF RIA Services support out-of-the-box though (so
yes, that is NOT in this talk )
•…

10. WCF and ASMX
Services

11. ASMX services (aka good old
webservices)
• ASMX services can be accessed without any change
• Communication is done asynchronously
• SOAP messages can be sent and received over
ASMX services
• From Visual Studio, use the default way of
connecting with a service
• Add service reference
• Generates proxy
• All Task-based!
• Use proxy-class with the async/await keywords

12. Accessing an ASMX
service from Windows
8
DEMO

13. WCF Services
• What is supported?
• Bindings:
• BasicHttpBinding
• NetTcpBinding
• NetHttpBinding
• CustomBinding
• Binding elements:
• BinaryMessageEncodingBindingElement
• TextMessageEncodingBindingElement
• ConnectionOrientedTransportBindingElement
• SslStreamSecurityBindingElement
• WindowsStreamSecurityBindingElement
• TcpTransportBindingElement
• Http(s)TransportBindingElement
• TransportSecurityBindingElement

14. WCF Services
• What is supported
• Encoding:
• Text, Binary
• Security modes:
• None, Transport, TransportWithMessageCredential, TransportCredentialOnly
(for BasicHttpBinding)
• ClientCredentialType:
• None, Basic, Digest, Negotiate, Ntlm, Windows
• Transfer Mode:
• Buffered, Streamed, StreamedRequest, and StreamedResponse
• Serializers:
• DataContractSerializer, DataContractJsonSerializer, XmlSerializer
• Miscellaneous:
• ChannelFactory
• DuplexChannelFactory
• CallbackBehavior

15. Things to note when working with
WCF (also goes for ASMX)
• No XML config file code
• Code gets generated in the Reference.cs file
• No config edit possible 
• Use the partial ConfigureEndpoint method
• Only Task-based methods are available
• Ensures there are no blocking calls
• Is done by default
• Specify Internet capability

16. Accessing a WCF
service
from Windows 8
DEMO

17. What about security for service
communication?
• WinRT supports sending credentials
• When building service that expects
credentials, generated code in Reference.cs will reflect
this
result.Security.Mode =
System.ServiceModel.BasicHttpSecurityMode.TransportCredentialOnly;
result.Security.Transport.ClientCredentialType =
System.ServiceModel.HttpClientCredentialType.Windows;
• https, custom validation are supported to enable
TransportWithMessageCredential
• Allows safe passing of username/password to service
endpoint

18. Secure
communication from a
Windows 8 app
DEMO

19. Working with REST
services

20. REST services
• No more WebClient, replaced with HttpClient
• Works with async
• Located in System.Net
• HttpClient defines
• Get(Async)
• Returns an HttpResponseMessage
• Put(Async)
• Post(Async)
• Delete(Async)
 RESTful!

21. Parsing the response
• XML
• Linq-To-XML
• XmlReader/XmlWriter
• XmlSerializer
• JSON:
• Use the JsonObject and feed it the returned string
• We can use the Parse() method
• Throws error if the returned string is faulty or invalid
• Also defines GetNamedString(), GetNamedNumber()
• Parsing via indexer
• Not recommended
• DataContractJsonSerializer is also available

22. Searching on Flickr
using the HttpClient
class
DEMO

23. Credential support with REST
services
• If REST service requires authentication , WinRT will
support it
• Some samples:
HttpClientHandler handler = new HttpClientHandler();
handler.UseDefaultCredentials = true;
HttpClient client = new HttpClient(handler);
using (var handler = new HttpClientHandler
{
Credentials = ...
})
using (var client = new HttpClient(handler))
{
var result = await client.GetAsync(...);
}

24. Secure REST
communication
DEMO

25. Working with oData
services

26. What is oData?
• Open Data Protocol
• Design goals ...
• Invent as little as possible
• Very low barrier of entry
• OData is a RESTful protocol
• Builds on HTTP and AtomPub
• Defines ...
• XML + JSON data representation
• Addressing scheme
• Query operators
• Metadata

27. Sample URIs
• http://odata.netflix.com/Catalog/
• AtomPub service document, list of all collections
• http://odata.netflix.com/Catalog/Genres
• all entries of a collection
• http://.../Catalog/Genres('Adventures')
• one entry by PK
• http://.../Catalog/Genres('Adventures')/Name
• one property as XML
• http://.../Catalog/Genres('Adventures')/Name/$value
• only the value

28. Navigation
• http://.../Catalog/Genres('Adventures')/Titles
• related entities
• http://.../Catalog/Genres('Adventures')/$links/Title
s
• only the links
• http://.../Catalog/Genres('Adventures')/Titles/$cou
nt
• count

29. Queries
• ... /Titles?$filter=AverageRating gt 4
• filters
• ... /Titles?$orderby=AverageRating desc,
ReleaseYear asc
• sorting
• .../Titles?$select=ShortName, ReleaseYear
• projection
• Paging support: $top, $skip, $skiptoken,
$inlinecount

30. oData and WinRT
• There’s an OData client library available
• Requires servers that comply with oData v1-v3
• Support for Add Reference since RC
• Previously we had to use the DataSvcUtil tool to
generate the proxy
• Still works if you want complete control over the proxy
generation

31. Working with oData
services
DEMO

32. Syndication

33. Syndication in general
• Real Simple Syndication
• RSS feeds expose information from sites mostly through
XML
• Feed is a list of syndication entries
• Post
• Author
• Data
• Links
•  Fixed set of elements
• Parsing it is possible
• Manually (if you like to hurt yourself…)
• Through a third-party library

34. Syndication in WinRT
• WinRT has the Windows.Web.Syndication namespace
• Contains SyndicationFeed and SyndicationClient classes
• Allows downloading feed asynchronously
• Can be provided with credentials if source requires them
• Supports
• Atom 0.3 and 1.0
• RSS 0.91, 0.92, 1.0 and 2.0)
• Returns items in an object model
var • Async (Task-based)
client = new SyndicationClient();
SyndicationFeed feed = await client.RetrieveFeedAsync(“<My RSS Feed>”);

35. Syndication
DEMO

36. Background transfers

37. Background transfers
• Just like Windows Phone 7, only 1 app can be the
main app
• Can be annoying if your app downloads files
• User can’t switch away or the download is interrupted
• Windows.Networking.BackgroundTransfer has a
BackgroundDownloader
• Creates DownloadOperation instances
• Can be paused, resumed...

38. Background transfers
• Support for
• Credentials
• Custom headers via SetRequestHeader
• Use for authentication methods such as cookies, forms-based
authentication...
• Progress reporting
• Managed through separate process:
BackgroundTransferHost.exe
• Keeps running in the background

39. Background transfers
DEMO

40. Tiles interactions

41. Types of notifications
• Local (from the app code)
• Can only be used when the app is running
• Useful for tile updates (not that useful for toasts)
• Scheduled
• Update at specific time
• Useful for tiles and toasts
• Periodic updates
• Push notifications

42. Periodic tile updates

43. Periodic tile updates
• Poor man’s live tiles
• Require nothing more than a service that returns
XML of a tile/badge update
• Great for distributing updates with wide audience

44. Periodic tile updates
• Setting it up:
• Build a service that returns an XML string
• Build a Metro app that calls the service and sets up periodic
tile/badge updates
• TileUpdater.StartPeriodicUpdate should be called with every start
of the application
• Service should update after about the same amount of time
polling happens
• If service is not available, Windows will retry only at the next
interval
• Service can be http or https
• App must declare internet capability
• No support for tile update queueing
• Don’t use it for breaking news!

45. Periodic Tiles
DEMO

46. Push Notifications

47. Types of notifications
• Local (from the app code)
• Can only be used when the app is running
• Useful for tile updates (not that useful for toasts)
• Scheduled
• Update at specific time
• Useful for tiles and toasts
• Periodic
• Update at specific interval
• Poll a cloud service for content
...?
• Push notifications are the missing link

48. Push notifications over WNS
• WNS = Windows Notification Service
• Allows delivery of tile and toast XML messages over the
wire
• Can arrive when the app isn’t running
• Create background processing without processing
• Happens on the server
• Transparent process for the developer
• Free services
• Cloud-based so no worries on scalability
• Easily updates millions of devices
• Register your app for now via
https://manage.dev.live.com/build

49. WNS architecture
1. Request Channel URI
2. Register with your Cloud Service
3. Authenticate & Push Notification

50. Push notifications using Azure
• What we need
• Secure, web based API for channel URI registration
• Persistent storage of channel URI
• Storage for tile and toast images
• What Azure offers us
• Windows Azure Compute
• Web Role
• Full IIS support
• WCF REST and ASP.NET MVC
• Windows Azure Storage
• Table Storage
• Blob Storage

51. Push notifications
DEMO

52. Authenticating using
the WebAuthBroker

53. The WebAuthBroker class
• The web authentication broker provides a set of
APIs and the infrastructure for apps to use Internet
authentication and authorization protocols such as
Oauth
• When an app calls the web authentication broker, the
user gets a dialog box in which the necessary webpages
are rendered to sign in
• After the user completes those steps, the dialog box
goes away and the user continues with the app

54. The WebAuthBroker class

55. Benefits of the WebAuthBroker
• An easy-to-use programming interface that frees
the app developer from hosting a browser control
within their own app
• User credentials that are isolated from the app
• Native support for single sign-on with online
providers
• Twitter
• Facebook
• Flickr
• …

56. How the WebAuthBroker
works
• The web authentication broker is the facilitator between
your app and authentication
• It consists of a set of APIs, a broker, and a web host.
• Your app uses the APIs to communicate with the broker.
• The broker creates a new web host process in a separate app
container
• The broker communicates with the app, assembles the UI and
controls the lifecycle of the web authentication host
• The web authentication host renders the pages from the online
provider's website

57. Authenticating using
the WebAuthBroker
DEMO

58. Using the Live SDK in
your Windows 8 apps

59. Live SDK Integration
• Using the Live SDK, we can, from WinRT apps:
• Leverage SSO functionality
• Access data in SkyDrive
• Integrate with Hotmail/Outlook and Messenger
• Requires the Live SDK 5.0 to be installed on your system
• Application needs to be registered with Windows Live
• http://manage.dev.live.com/build
• Only need the package name
• Requires that you are signed in with a Live ID/Microsoft
account
• We can log in using a live account or a local account
• It’s possible to switch between the two

60. Live SDK Integration
• The device has to be trusted
• In the screenshot below, this hasn’t been done yet 

61. To integrate…
• We can use some of the built-in controls in the SDK
<live:SignInButton Name="MySignInButton" Scopes="wl.signin wl.basic wl.contacts_create"/>
• Scope
• A scope grants a permission level
• Can be:
• wl.signin
• Single sign-in behavior
• wl.basic
• Read access to a user's basic profile info. Also enables read access to a user's
list of contacts
• wl.contacts_create
• Creation of new contacts in the user's address book
• wl.calendars_update
• Read access to a user's personal, preferred, and business email addresses
• …
• Complete list at http://msdn.microsoft.com/en-
us/library/live/hh243646.aspx

62. Accessing SkyDrive from your
apps
• Windows 8 integrates with SkyDrive (cloud)
• Metro Apps can use SkyDrive through the Live SDK
• Enables single sign-on using your Microsoft account
• Don’t bother the user asking to login with every app
• App automatically knows who you are
• Called the easy sign-in
• Users can use the machine with their Microsoft
account
• Apps can benefit from this as well using Live SDK
• User needs to grant permission though (once)

63. Using the Live SDK in
your Windows 8 apps
DEMO

64. Using roaming data in
your applications

65. Roaming data
• Users can personalize their devices and settings
• Windows and the built-in apps create a “connected”
experience
• Configure once, use everywhere
• Roaming application data makes creating this for us very
easy
• App data can be local, roaming or temporary
• Roaming will make sure that the data is synced to the cloud and
other devices where the Microsoft account uses the particular
app

66. Roaming data
• What to place in roaming data?
• Data that is relevant to the app that created it
• Settings
• Temporary document
• Level in a game
• App state
• Context
• Data that should not be placed in roaming data
• Data that can be read/shared with other apps
• Documents, pictures, exported data
• Data that should be exported to SkyDrive
• Limit is currently 100k
• Preserve battery and performance
• Can be checked using the RoamingStorageQuota class
• If limit is surpassed, no data will be synced at all
• It’s vital to only sync URIs instead of full pages

67. Example of roaming data
• RSS reader app where the user can save how many
items he wants to see on his screen
Windows.Storage.ApplicationData.Current.RoamingSettings.Values[“ItemsPerPage”] = 10;
• If you want to save the last article ID and want to
create a continuous experience, name the setting
HighPriority
Windows.Storage.ApplicationData.Current.RoamingSettings.Values[“HighPriority”] =
currentFeedId;

68. Example of roaming data
• If more than one setting need to be synced
together, we can use a CompositeSettingValue
Windows.Storage.ApplicationDataCompositeValue currentFeed =
new Windows.Storage.ApplicationDataCompositeValue();
currentFeed.Insert(“CurrentFeedId”, currentFeedId);
currentFeed.Insert(“CurrentFeedPage”, currentFeedPage);
Windows.Storage.ApplicationData.Current.RoamingSettings.Values[“HighPriority”] =
currentFeed;
• With the app running, the app can register for the
DataChanged event on the ApplicationData class
• Will fire when the application data has changed

69. Some best practices around
roaming data
• Only works with a Microsoft account
• The device has to be trusted before roaming data
will work
• Don’t use it for simultaneous use of applications on
more than one device at a time
• Last save wins
• Write often-changing only every now and then
• Don’t use it to constantly write the location within a
song
• Writing too often can result in the device being locked-
out for a certain amount of time

70. Using roaming data in
your applications
DEMO

71. Working with sockets

72. Types of socket communication in
WinRT
• StreamSocket - Used to support network communication
using a TCP stream socket
• StreamSocketListener - Used to support listening for an
incoming network connection using a TCP stream socket
• DatagramSocket - Used to support network communication
using a UDP datagram socket
• MessageWebSocket - Used to support network
communication that allows reading and writing whole
messages using a WebSocket
• StreamWebSocket - Used to support network
communication that allows reading and writing streams
using a WebSocket
• All live in the Windows.Networking.Sockets namespace

73. When and when not to use
sockets
Requirement Solution
Connects to a network service that uses an TCP or UDP sockets
existing protocol (SMTP, POP, IMAP, or MAPI
for mail, for example) that is not directly
supported by other networking features
Connects to another machine on the same TCP or UDP sockets
local network
Requires a simple requestresponse protocol Representational State Transfer (REST) APIs
that can communicate through HTTP proxies that are available using C#, VB.NET, and C++
Requires socket-like semantics (asynchronous, WebSockets
bi-directional transfers) to connect across the
Web, including through HTTP proxies.

74. TCP Sockets

75. TCP Sockets
• TCP and UDP can be used to send and receive data in
WinRT apps
• Based on classes from the
Windows.Networking.Sockets namespace
• StreamSocket
• StreamSocketListener
• DatagramSocket
• Support for
• Making client connections
• Listening for connections
• Operating as a server, or for both client and server operations

76. TCP Sockets
• Steps to get TCP sockets working in your Metro app
• Use the StreamSocket class to create a TCP socket
• ConnectAsync on the StreamSocket class allows making a
network connection to a TCP network server
• Streams.DataWriter allows sending data to the server
• Basically allows writing common types on a stream
• Streams.DataReader allows reading data from a server
• Basically allows reading common types from a stream
• StreamSocket object can be configured to use SSL/TLS
for communications between the client and the server.
• This support for SSL/TLS is limited to using the StreamSocket
object as the client in the SSL/TLS negotiation

77. Using the StreamSocket
• This class enables network communication using a TCP
stream socket
• What you can do with the StreamSocket
• After instantiation of the StreamSocket, get a StreamSocketControl
object using the Control property
• Allows setting any properties on the StreamSocketControl object before
calling one of the ConnectAsync methods
• Use one of the ConnectAsync methods to establish a connection
with the remote endpoint
• Can be configured for use with SSL
• Get the OutputStream property to write data to the remote host
• Get the InputStream property to read data from the remote host
• Read and write data as needed
• Call the Close method to abort any pending operations
• Releases all unmanaged resources associated with the StreamSocket
object

78. Using the
StreamSocketListener
• This class enables listening for an incoming network
connection using a TCP stream socket and accepting the
connection
• What you can do with the StreamSocketListener
• After instantiation of the StreamSocketListener, use the Control
property to retrieve a StreamSocketListenerControl object
• Can be used to set the socket quality of service
• Assign the ConnectionReceived event to an event handler
• Call the BindServiceNameAsync or BindEndpointAsync method to
bind to a local TCP port or service name
• After an incoming connection is received, use the
StreamSocketListenerConnectionReceivedEventArgs object to
retrieve the Socket property with the StreamSocket object created
• Use the StreamSocket object to send and receive data
• Call the Close method to stop listening for and accepting incoming
network connections
• Releases all unmanaged resources associated with the
StreamSocketListener object.

79. TCP Sockets
DEMO

80. WebSockets

81. What’s a WebSocket?
• The WebSocket Protocol defines a mechanism for
two-way communication between a client and a
server.
• To establish a WebSocket connection, a specific, HTTP-
based handshake is exchanged between the client and
the server.
• If successful, the application-layer protocol is
"upgraded" from HTTP to WebSockets, using the
previously established TCP connection. Once this
occurs, HTTP is completely out of the picture
• Data can be sent or received using the WebSocket protocol by
either endpoint at any time, until the WebSocket connection is
closed
• Only works when the server has a WebSocket

82. Two types of WebSockets
exist
MessageWebSocket StreamWebSocket
Suitable for scenarios in which large
Suitable for typical scenarios where
files (such as photos or movies) are
messages are not extremely large
being transferred
Enables notification that an entire Allows sections of a message to be
WebSocket message has been received read with each read operation.
Supports both UTF-8 and binary
Supports only binary messages
messages

83. Using WebSockets
from a Metro style
application
DEMO

84. Summary
• Windows 8 supports many types of services
• Most common including WCF, ASMX, oData work
similarly to Silverlight
• Async/await pattern makes development easier
• More complex types including oAuth and sockets
are pretty easy using WinRT API
• Support for security

85. Q&A

86. Thanks!

87. Windows 8,
Metro apps
and the outside world
Gill Cleeren
Microsoft Regional Director & MVP
Telerik MVP