WCF: Building RESTful Services

1. WCF: Building RESTful Services  Steve Maine Senior Program Manager Microsoft Corporation

2. Source: Pingdom.com

3. 1993: Web == Content

4. Content-Driven Web Architecture • The Browser • Generic client experience • URI’s • Addressing and identification • HTML • Common presentation format • Hyperlinks • Anarchic interconnectivity • HTTP GET • Common operation everything supports

5. 2008: Web == Content + Capabilities

6. Capability-Enabled Web Architecture • Rich Browser Clients • Programmability via script or plugins • HTTP • Baseline application protocol • Common set of operations + status codes • Domain-neutral data-oriented formats • JSON, Atom/Atom Publishing • Refine to support domain-specific schemas • Presentation formats • HTML, CSS

7. RESTful Tenents • The Web is a graph of linked Resources • Resources are identified by URI’s • Resources support a fixed set of operations • In practice, these are defined by HTTP • Applications follow links to achieve late binding REST is an architectural style, not a specification

8. REST Continuum • Well Constructed URIs • HTTP Verbs • GET – Fetch • PUT – Update/Insert • DELETE – Delete • POST – Append • Standard Representations RESTfullness Purists Pragmatists • POST to 1 URI OKQuerystrings OK • HTTP Verbs • GET – Fetch • POST – Overloaded • AJAX Services • POX OK

9. demo AJAX Services with WCF

10. webHttpBinding • New “web-friendly” WCF Binding in Fx 3.5 • Allows for the development of RESTful services • Does not use SOAP envelopes • HTTP and HTTPS Transports Only • Supports several wire formats: • XML • JSON • Binary (streams)

11. WebServiceHost • Specialized SerivceHost for RESTful services • Eliminates need for lots of configuration • Automatically configures address, binding, contract • Optimized for single-endpoint services • Use from .svc file: <%@ ServiceHost Language="C#" Debug="true" Service="Caching1.FeedService" Factory=“System.ServiceModel.Activation.WebServiceHostFactory” %>"%>

12. [WebGet] And [WebInvoke] • Binds a WCF operation to URI space and HTTP method • Indicate the HTTP Method for the operation • WebGet – Don’t make me write it • WebInvoke – All verbs other than GET (Method parameter takes in the name of the Verb) • Other Parameters • BodyStyle – Indicates whether the Request/ Response are wrapped or not • RequestFormat – Json or Xml • ResponseFormat – Json or Xml • UriTemplate – Rich binding to URI

13. UriTemplate • String that allows you to define the structure of the URI, as well as to define “Holes” • The “Holes” are variables • You Bind the template with parameters to fill the holes • {productId} hole / variable gets bound to productId parameter in operation Variable [OperationContract] [WebGet(UriTemplate=“product/{productId}")] ProductGetProduct(intproductId);

14. announcing WCF REST Starter Kit

15. WCF REST Starter Kit • Microsoft.ServiceModel.Web.dll • New features supporting RESTful services • Visual Studio 2008 Templates • REST Collections/Singleton Services • Atom Feed/Atom Publishing Protocol • HTTP/POX Services • REST Samples • Codeplex Project • Released at PDC • Written by WCF team • Features may be included in .NET 4.0

16. demo The REST 0f WCF

17. What We've Talked About Today • REST and the “zen” of the web • WCF features for REST scenarios • [WebGet] + [WebInvoke] • UriTemplate • WebHttpBinding • And many more… • The WCF REST Starter Kit • Available today at http://msdn.com/wcf/rest

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20. © 2008 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries. The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

22. WebGet/WebInvoke Examples [OperationContract] [WebInvoke( Method=“PUT", ResponseFormat=WebMessageFormat.Json, UriTemplate=“product/{productId}")] ProductUpdateProduct(intproductId, product p); [OperationContract] [WebGet( ResponseFormat=WebMessageFormat.Json, UriTemplate=“product/{productId}")] ProductDataGetProduct(intproductId);

23. WebProtocolException • CLR Exception that can be turned into HTTP status code on the wire • Can optionally carry detail information for display in the browser [OperationContract, WebGet] Stream EchoText(string text) { if( text == null ) throw new WebProtocolException( HttpStatusCode.BadRequest ); . . . }

24. AdapterStream • Used when you want a Stream or TextWriter but don’t have one handy [OperationContract, WebGet] Stream EchoText(string text) { return new AdapterStream( textWriter => { textWriter.WriteLine("You said: "); textWriter.WriteLine(text); textWriter.Flush(); }, Encoding.UTF8); }

25. Request Interceptors • MessageInspectors at the channel layer • Think of them like a per-service pipeline • Arbitrary message manipulation prior to dispatch; can prevent dispatch too public class XHttpMethodOverrideInterceptor:RequestInterceptor { public override void ProcessRequest( ref RequestContextrequestContext) { //Change the HTTP method used for dispatch based on //the X-HTTP-Method-Override header } }

26. [WebCache] • Integrates WCF operations with ASP.NET caching (requires ASP.NET Compat Mode) • Cache profile stored in Web.config [OperationContract, WebGet] [WebCache(CacheProfileName="CacheFor1Min")] public Atom10FeedFormatter GetFeed(inti) { … } <system.web> <caching> <outputCacheSettings> <outputCacheProfiles> <add name="CacheFor1Min" duration="60" enabled="true" location="Any" varyByParam=“i"/> </outputCacheProfiles> </outputCacheSettings> </caching> </system.web>

27. ASP.NET Authentication Support • “It just works” with ASP.NET • Full support for Membership + Roles • Requires ASP.NET Compatibility Mode [OperationContract, WebGet] [PrincipalPermission(SecurityAction.Demand, Role=“admin")] SampleResponseBodyGetData(inti, string s)