Working with Data and Web Services in Silverlight 2

1. Working with Data and Web Servicesin Silverlight 2 Gill Cleeren Microsoft Regional Director Microsoft MVP ASP.NET Ordina Belgium www.snowball.be - www.codeflakes.net gill.cleeren@ordina.be

2. Get to know the audience… Is this Silverlight?

3. Agenda Introduction Building ourfirst Silverlight/WCF application Services thatdescribethemselves Services thatdon’tdescribethemselves Accessing RSS/Atomfeeds Summary

4. Applications interact with the outside world Product catalog Productdatabase Search string Product information

5. Many Types of Outside Data ImagesSoundsVideos RSS/AtomFeeds New servicesyou build In-Browser Application ExistingIntranetservices PublicInternetmashup APIs

6. A Bit of History: Silverlight 1.0 ImagesSoundsVideos RSS/AtomFeeds <XAML/> 1.0 New servicesyou build ? ExistingIntranetservices JavaScript PublicInternetmashup APIs AJAX (XmlHttpRequest) HTML

7. The Story Today: Silverlight 2 ImagesSoundsVideos RSS/AtomFeeds 2 New servicesyou build Managed Code (C#/VB) ExistingIntranetservices PublicInternetmashup APIs HTML

8. Question 1:What does the client code look like? 2 Managed Code (C#/VB)

9. Question 2:What is the recommended way to create services for Silverlight? New servicesyou build

10. Using a Custom Service from Silverlight DEMO Productdatabase Service

11. Recap: Required Steps WCFService • 1. Create the Service • 2. Define what it does • 3. “Add Service Reference” • 4. Use the Service!

12. Creating a Service for Silverlight “Add New Item” (in Web Site / Web App) “Silverlight-Enabled WCF Service” Temporary for Beta1: “Add New Item”  “WCF Service” Change wsHttpBinding  basicHttpBinding in config basicHttpBinding <endpoint contract=“IShoppingService” binding=“wsHttpBinding”…>

13. Defining the Contract • [ServiceContract] for the service class (interface in Beta1) • [OperationContract] for methods (in the interface in Beta1) • [DataContract]/[DataMember] for data types • [ServiceContract] • public class ShoppingService{ • [OperationContract] • Product[] GetProducts(string searchString) { /*... Implementation ... */ }} • [DataContract] • public class Product{ • [DataMember] • public string description; • [DataMember] • public string pictureUrl; • } Nothing Silverlight-specificRegular WCF code!

14. Adding a Reference In the Silverlight project: “Add Service Reference” “Discover” button will find services in solution Can also give external URL

15. Creating the Proxy var proxy = new ShoppingServiceClient(); Default address chosen if no parameters given Can pass in address manually But what if the service moves? • Configuration support after Beta1 • No need to recompile Silverlight client code if service moves • Can reuse one Silverlight app for many services

16. Making the Call Only asynchronous calls supported • Set up GetProductsCompletedevent • “Tab,Tab” in Visual Studio • Call GetProductsAsync var proxy = newShoppingServiceClient(); proxy.GetProductsCompleted += newEventHandler<GetProductsCompletedEventArgs>(proxy_GetProductsCompleted); proxy.GetProductsAsync(“book”); void proxy_GetProductsCompleted(object sender, GetProductsCompletedEventArgs e) { // Process response… }

17. Data Binding to Services All generated types/collections support data binding Future Possibility: Advanced data binding to services (XAML-only)E.g. <GetProductsDataSource />

18. What we covered so far… ImagesSoundsVideos RSS/AtomFeeds 2 New servicesyou build ExistingIntranetservices But what about the client code for other service types? PublicInternetmashup APIs

19. Approach #1:"Add Service Reference" Metadata-driven, with Intellisense

20. Services that describe themselves Services for your Silverlightproject SOAPservices in the enterprise WCF SOAP services on the Internet Automatic Proxy Generation Computer-ReadableMetadata (e.g. WSDL) SQL Server Data Services*(Astoria)

21. Demo:Accessing the Live Search APIfrom Silverlight in an automatic way

22. Add Service Reference Works with: • Any “simple” SOAP service (e.g. Live Search) • SOAP 1.1 • Server-side may be JAVA, WCF, ASMX, etc. • A few restrictions (e.g. SOAP Faults not supported) • Future Possibility: SQL Server Data Services (Astoria) Can’t talk to just any service: Silverlight-Wide Cross-Domain Restrictions…

23. Cross-Domain Restrictions Silverlight does not allow applications to cross domain boundaries by default: • MySite.com/silverlightApplication.xap cannot call SomeOtherSite.com/someService.svc • SecurityException if you try Silverlightallows the calls if target site opts in • How do services opt in? • When should services opt-in?

24. Cross-Domain Policy Files Silverlight looks for two policy files: • Silverlight policy: clientaccesspolicy.xml • Adobe Flash policy: crossdomain.xml • Already used by All public services that work with Flash will also work with Silverlight!

25. Cross-DomainPolicy Files <?xml version="1.0" ?> <cross-domain-policy> <allow-access-from domain="*" /> </cross-domain-policy> <?xml version="1.0" encoding="utf-8" ?> <access-policy> <cross-domain-access> <policy> <allow-from> <domain uri="*" /> </allow-from> <grant-to> <resource path="/" include-subpaths="true" /> </grant-to> </policy> </cross-domain-access> </access-policy>

26. Approach #2:Write the Code Manually “A service call is just an HTTP request”

27. Human-Readable Documentation Only

28. Services that don’t describe themselves “Mashup APIs” “Web APIs” REST Services “POX” (Plain Old XML) services Some Manual Work Required Human-ReadableDocumentation JSON Services 1. Build a URL 2. Make a request 3. Work with request/response data (XML or JSON)

29. Demo:Accessing Flickr from Silverlight

30. Manually Issuing Requests Code was exactly as in the regular .NET Framework!Good news for existing .NET developers Some Silverlight-specific things to be aware of…

31. Manually Issuing Requests • Build a URL • What are the allowed protocols? • Where can I connect to? • Make a Request • How do I make a request? • Working with Request/Response Data • How do I work with XML? • How do I work with JSON?

32. Manually Issuing Requests • Build a URL • What are the allowed protocols? • Where can I connect to? • Make a Request • How do I make a request? • Working with Request/Response Data • How do I work with XML? • How do I work with JSON?

33. Allowed URLs HTTP and HTTPS • Some restrictions on HTTPS, cross-scheme • A few of these will go away after Beta1 Subject to cross-domain rules • Must have policy file if not local URL No ftp:// or file:// URLs

34. Manually Issuing Requests Build a URL • What are the allowed protocols? • Where can I connect to? Make a Request • How do I make a request? Working with Request/Response Data • How do I work with XML? • How do I work with JSON?

35. Making HTTP Requests WebClient • Simple to use • Limited functionality HttpWebRequest • Access to all features

36. Manually Issuing Requests Build a URL • What are the allowed protocols? • Where can I connect to? Make a Request • How do I make a request? Working with Request/Response Data • How do I work with XML? • How do I work with JSON?

37. Working with XML XmlReader/XmlWriter Linq to XML XmlSerializer static void w_DownloadStringCompleted(object sender DownloadStringCompletedEventArgs e) { XElement x = XElement.Parse(e.Result); foreach (photo in x.Elements("photo")) { //... } }

38. The JSON Data Format “JavaScript Object Notation” • Easy and fast to parse in JavaScript in browsers Often no real reason to use it for SL, except… • Reusing existing services built for AJAX pages • Smaller message size (but binary XML is a future possibility) Example: {“Person”:{“name”:”john”,”age”:42}}

39. Approach #3:Use Built-In Classes … for RSS/Atom feeds

40. Consuming Feeds RSS 2.0 Feeds Atom 1.0 Feeds Built-in classes to work withsuch services Conform to a Standard AtomPublishing (Future?) SyndicationFeed feed = SyndicationFeed.Load(…) foreach (SyndicationItem item in feed) { //Do something with item }

41. Demo: Accessing my blogs RSS feeds from Silverlight

42. Syndication Support in Silverlight Protocols • RSS 2.0, Atom 1.0 • Future possibility: Atom Publishing Protocol Essentially the same as in .NET 3.5 • SyndicationFeed, SyndicationItem, etc. • Can read / write feeds Subject to same cross-domain restrictions, etc. Use HttpWebRequest/WebClient, then Syndication to parse

43. Summary: What We Covered Creating Services for Silverlight • Creating and consuming WCF services • Securing local services • Creating public services (safe for cross-domain) Accessing Services that Describe Themselves • “Add Service Reference” Accessing Services that Don’t Describe Themselves • WebClient / HttpWebRequest, manual work Accessing Feeds • RSS/Atom

44. Resources Silverlight: www.silverlight.net silverlight.net/blogs/jesseliberty/ timheuer.com/blog/ www.silverlightcream.com Personal blogs: www.snowball.be www.codeflakes.net Email: gill.cleeren@ordina.be

45. Q&(maybe)A

46. Thankyou! Gill Cleeren Microsoft Regional Director Microsoft MVP ASP.NET Ordina Belgium www.snowball.be - www.codeflakes.net gill.cleeren@ordina.be