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There is time for REST

WCF REST Services

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Overview

• What is REST• Rules and Guidelines• Hosting a REST Service in .NET• Consuming a REST Service with .NET• Samples• Discussion

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What is REST?

• Roy Fieldinghttp://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm

• Client-Server• Stateless• Cachable• Layered System

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REST Constraints

• Separation resource from representation• Uniform interface• Self-descriptive messages• Hypermedia as engine of application state

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HTTP Methods

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HTTP Methods

• Retrieves a resource• Guaranteed not cause side-effect (SAFE)• Cacheable

GET

• Creates new resource• Unsafe, effect of this verb isn’t defined by

HTTPPOST

• Updates existing resource• Can call N times, same thins will always

happen (idempotent)PUT

• Removes an resource• IdempotentDELETE

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HTTP Status Codes

Status Range Description Examples

100 Informational 100 Continue

200 Successful 200 OK

201 Created

202 Accepted

300 Redirection 301 Moved Permanently

304 Not Modified

400 Client error 401 Unauthorized

402 Payment Required

404 Not Found

405 Method Not Allowed

500 Server error 500 Internal Server Error

501 Not Implemented

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HTTP Messages

GET http://localhost:1128/api?$skip=2&$top=2 HTTP/1.1User-Agent: FiddlerHost: localhost:1128Accept: application/xml

HTTP/1.1 200 OKCache-Control: privateContent-Length: 157Content-Type: application/xml; charset=utf-8Server: Microsoft-IIS/7.5Date: Fri, 26 Aug 2011 18:51:22 GMT

<?xml version="1.0" encoding="utf-8"?><Data />

Response

Request

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URIs

• RPC (SOAP) Interface

http://example.com/CarsService/getYears

http://example.com/CarsService/getMakes

http://example.com/CarsService/getAutomobile

http://example.com/CarsService/updateAutomobile

http://example.com/CarsService/deleteAutomobile

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URIs

• RESTful Interface–No need to distinguish get/update/delete,

that’s what the HTTP Method is for–Collection

http://example.com/2011/Honda/ –Resource

http://example.com/2011/Honda/Civic/2.0

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Return Types

• XML– XHTML– ATOM Publishing Protocol– RSS– Custom (should contain hyperlinks)

• JSON• Custom

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WCF and REST

WCF 3.5 REST

Starter Kit

WCF 4 REST

WCF Web Api

WCF 4 REST– REST endpoints– Uri templates for routing– WCF Hosting (Console, IIS, etc) etc.

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WCF 4 REST, Web Api

• Programming model for HTTP in WCF– Access HTTP from top to bottom– REST endpoints– Uri templates for routing– WCF Hosting (Console, IIS, etc) etc.

• Http Client• Plug in any format / media type• Typeless JSON support• IQueryable support

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WCF REST contract

[ServiceContract]public interface IAutomobileService{ [OperationContract] [WebGet(UriTemplate = "*")] Message Get();

[OperationContract] [WebInvoke(Method = "PUT", UriTemplate = "*")] Message Put(Message data);}

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Uri Templates

[ServiceContract]public interface IAutomobileService{ [OperationContract] [WebGet(UriTemplate = "/{year}/{make}/{model}/{engine}")] Automobiles GetAutomobiles(string year, string make, string model, string engine);

}

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Routing

static void RegisterRoutes(RouteCollection routes){ routes.MapServiceRoute<SampleResource>("api");}

void Application_Start(object sender,EventArgs e){ RegisterRoutes(RouteTable.Routes);}

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Consuming REST .NET

HttpWebRequest

WebClient

WebChannelFactory

HttpClient

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WebRequest

var httpRequest = (HttpWebRequest)WebRequest.Create("http://localhost/myservice");

 using (var upStream = httpRequest.GetRequestStream()){ // some complicated logic to create the message} var response = httpRequest.GetResponse();using (var downStream = response.GetResponseStream()){ // some complicated logic to handle the response message.}

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WebChannelFactory

[ServiceContract]public interface ITwitterService{ [OperationContract] [WebInvoke(UriTemplate = "/friendships/create/{user}.xml")] TwitterUser CreateFriendship(string user);} using (var factory = new WebChannelFactory<ITwitterService>(

new Uri("http://www.twitter.com/"))){ factory.Credentials.UserName.UserName = username; factory.Credentials.UserName.Password = password; var proxy = factory.CreateChannel(); var user = proxy.CreateFriendship("userToFollow");}

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HttpClient

var sample = new Sample();

using (var client = new HttpClient()){ client.DefaultRequestHeaders.Accept.Add( new MediaTypeWithQualityHeaderValue("application/json"));

client.Post( "http://localhost/myservice", new ObjectContent(typeof(Sample), sample, Sample.JsonMediaType));}

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Tools

• Fiddlerhttp://www.fiddler2.com/fiddler2/

• Firebughttp://getfirebug.com

• IEWatchhttp://www.iewatch.com/

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SHOW ME THE CODE

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Implementations

• OpenRastaOpenRasta brings the concept of REST to the .NET platform in ways that allow it to be deployed alongside ASP.NET and WCF components. http://trac.caffeine-it.com/openrasta/wiki/Doc

http://code.google.com/p/implementing-rest/wiki/ByLanguage

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Books

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Resources

WCF Web API

• http://wcf.codeplex.com

WCF Web APis: "There's a URI for That"

• http://channel9.msdn.com/Events/MIX/MIX11/FRM14

RFC HTTP

• http://www.ietf.org/rfc/rfc2616.txt

Implementing REST, small reference and list of frameworks

• http://code.google.com/p/implementing-rest/

REST on Wikipedia

• http://en.wikipedia.org/wiki/REST

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