Building RESTful Services with WCF 4.0

Building RESTful Services with WCF 4.0

• 1.
  Building RESTful Serviceswith WCF Aaron Skonnard Cofounder, Pluralsight
• 2.
  Overview
• 3.
  Why REST?
• 4.
  Why REST? 1. Mostfolks don't need SOAP's key features Transport-neutrality Advanced WS-* protocols Basic SOAP is just like REST but w/out the benefits
• 5.
  Why REST? 2. RESTis simple and the interface is uniform It's just HTTP + XML/JSON/XHTML Uniform interface that everyone understands Therefore, it’s more interoperable!
• 6.
  REST is notRPC SOAP emphasizes verbs while REST emphasizes nouns or "resources" SOAP REST With REST, you define resources, getUser() and use a uniform interface to addUser() User { } operate on them (HTTP verbs) removeUser() Location { } ... getLocation() XML representation addLocation() ... <user> <name>Jane User</name> With SOAP, you define <gender>female</gender> custom operations (new <location href="http://example.org/locations/us/ny/nyc" >New York City, NY, US</location> verbs), tunnels through </user> POST
• 7.
  Is REST toosimple for complex systems?
• 8.
  Why REST? 3. RESTis how the Web works It scales from HTTP's built-in caching mechanisms Caching, bookmarking, navigating/links, SSL, etc You can access most REST services with a browser
• 9.
  REST in WCF
• 10.
  Windows Communication Foundation WCFdoesn't take sides – it provides a unified programming model And allows you to use SOAP, POX, REST, whatever data format, etc Architecture: SOAP, REST, distributed objects, etc Transport Protocol: HTTP, TCP, MSMQ, etc WCF Message format: XML, RSS, JSON, binary, etc Message protocols: WS-*, none, etc
• 11.
  WCF programming styles Mostof the built-in WCF bindings use SOAP & WS-* by default You have to configure them to disable SOAP WCF 3.5 comes with a new Web (REST) programming model Found in System.ServiceModel.Web.dll Allows you to map HTTP requests to methods via URI templates You enable the Web model with a new binding/behavior Apply to messaging layer using WebHttpBinding Apply to dispatcher using WebHttpBehavior
• 12.
  WebServiceHost WebServiceHost simplifes hosting Web-based services Derives from ServiceHost and overrides OnOpening Automatically adds endpoint for the base address using WebHttpBinding Automatically adds WebHttpBehavior to the endpoint ... this host WebServiceHost host = new WebServiceHost( adds the typeof(EvalService), Web binding new Uri("http://localhost:8080/evals")); & behavior host.Open(); // service is up and running Console.ReadLine(); // hold process open ... <%@ ServiceHost Language="C#" Service="EvalService" Factory= "System.ServiceModel.Activation.WebScriptServiceFactory" %>
• 13.
  WebGetAttribute WebGetAttribute maps HTTPGET requests to a WCF method Supply a UriTemplate to defining URI mapping The UriTemplate variables map to method parameters by name BodyStyle property controls bare vs. wrapped Request/ResponseFormat control body format URI template [ServiceContract] public interface IEvalService { [WebGet(UriTemplate="evals?name={name}&score={score}")] [OperationContract] List<Eval> GetEvals(string name, int score); ...
• 14.
  WebInvokeAttribute WebInvokeAttribute maps allother HTTP verbs to WCF methods Adds a Method property for specifying the verb (default is POST) Allows mapping UriTemplate variables Specify which Body is deserialized into remaining parameter HTTP verb this responds to [ServiceContract] public interface IEvals { [WebInvoke(UriTemplate ="/evals?name={name}",Method="PUT")] [OperationContract] void SubmitEval(string name, Eval eval /* body */); ...
• 15.
  WebOperationContext Use WebOperationContext toaccess HTTP specifics within methods To retreived the current context use WebOperationContext.Current Provides properties for incoming/outgoing request/response context Each context object surfaces most common HTTP details URI, ContentLength, ContentType, Headers, ETag, etc
• 16.
  WebMessageFormat WCF provides supportfor two primary Web formats: XML & JSON You control the format via RequestFormat and ResponseFormat [ServiceContract] public interface IEvals { [WebGet(UriTemplate = "/evals?name={nameFilter}", ResponseFormat = WebMessageFormat.Json)] [OperationContract] List<Eval> GetCurrentEvals(string nameFilter); ... Specify the message format
• 17.
  Syndication programming model WCF comes with a simplified syndication programming model The logical data model for a feed is SyndicationFeed You can use it to produce/consume feeds in a variety of formats You use a SyndicationFeedFormatter to work with a specific format Use Atom10FeedFormatter or RSS20FeedFormatter today [ServiceKnownType(typeof(Atom10FeedFormatter))] [ServiceKnownType(typeof(Rss20FeedFormatter))] [ServiceContract] public interface IEvalService { [WebGet(UriTemplate = "evalsfeed")] [OperationContract] allows you to return SyndicationFeedFormatter GetEvalsFeed(); an Atom or RSS feed ... }
• 18.
  New in 4.0
• 19.
  Improved REST Support Manyfeatures in the WCF REST Starter Kit are now part of WCF 4.0
• 20.
  Automatic help page WCF4 provides an automatic help page for REST services Configure the <webHttp> behavior with helpEnabled=“true”
• 21.
  Message format selection WCF4 also provides automatic format selection for XML/JSON This feature is built on the HTTP “Accept” headers <configuration> <system.serviceModel> <standardEndpoints> <webHttpEndpoint> <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true"/> </webHttpEndpoint> </standardEndpoints> </system.serviceModel> </configuration>
• 22.
  Http caching support WCF4 provides a simpler model for managing HTTP caching They built on the ASP.NET caching profile architecture You define an [AspNetCacheProfile] for your GET operations Shields you from dealing with HTTP caching headers yourself [AspNetCacheProfile("CacheFor60Seconds")] [WebGet(UriTemplate=XmlItemTemplate)] [OperationContract] public Counter GetItemInXml() { return HandleGet(); }
• 23.
  REST project templates Downloadthe new REST project templates via the new Visual Studio 2010 Extension Manager (Tools | Extension Manager)
• 24.
  What about OData?
• 25.
  WCF Web Api Futures http://wcf.codeplex.com