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WCF:
Building RESTful
Services
S Steve Maine
Senior Program
Manager
Microsoft Corporation

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

2008:
Web == Content +
Capabilities

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

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

REST Continuum

Purists RESTfullness Pragmatists

 Well Constructed URIs  POST to 1 URI OK
Querystrings OK
 HTTP Verbs
 HTTP Verbs  GET – Fetch
 GET – Fetch  POST – Overloaded
 PUT – Update/Insert
 DELETE – Delete
 POST – Append
 AJAX Services
 Standard Representations
 POX OK

demo
AJAX Services
with WCF

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)

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”
%>"%>

[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

 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
Variable
[OperationContract]
[WebGet(UriTemplate=“product/{productId}")]
Product GetProduct(int productId);

 {productId} hole / variable gets bound
to productId parameter in operation

announcing
WCF REST
Starter Kit

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

demo
The REST
0f WCF

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

Evals & Recordings

l
Please fil This sess
ion will
r
out you be availa
ble as
evalua tion for a record
: ing at:
this se ssion at

www.microsoftpdc.com

QA &

Please use the microphones
provided

© 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.

WebGet/WebInvoke Examples

[OperationContract]
[WebGet( ResponseFormat=WebMessageFormat.Json,
UriTemplate=“product/{productId}")]
ProductData GetProduct(int productId);

[OperationContract]
[WebInvoke( Method=“PUT",
ResponseFormat=WebMessageFormat.Json,
UriTemplate=“product/{productId}")]
Product UpdateProduct(int productId, product p);

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 );
. . .
}

AdapterStream

 Used when you want a Stream or
TextWriter but don’t have one handy

Stream EchoText(string text)
{
return new AdapterStream( textWriter =>
{
textWriter.WriteLine("You said: ");
textWriter.WriteLine(text);
textWriter.Flush();
}, Encoding.UTF8);
}

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 RequestContext requestContext)
{
//Change the HTTP method used for dispatch based on
//the X-HTTP-Method-Override header
}
}

[WebCache]

 Integrates WCF operations with ASP.NET
caching (requires ASP.NET Compat Mode)
 Cache profile stored in Web.config
[WebCache(CacheProfileName="CacheFor1Min")]
public Atom10FeedFormatter GetFeed(int i) { … }

<system.web>
<caching>
<outputCacheSettings>
<outputCacheProfiles>
<add name="CacheFor1Min" duration="60"
enabled="true" location="Any" varyByParam=“i"/>
</outputCacheProfiles>
</outputCacheSettings>
</caching>
</system.web>

ASP.NET Authentication Support

 “It just works” with ASP.NET
 Full support for Membership + Roles
 Requires ASP.NET Compatibility Mode

[PrincipalPermission(SecurityAction.Demand, Role=“admin")]
SampleResponseBody GetData(int i, string s)

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