WCF provides first-class support for building "Web" services that embrace REST design principles using standard Web protocols and data formats. This session illustrates how to build WCF services that support the HTTP uniform interface and different resource representations like XML, JSON, and Atom to enhance your Web 2.0 mash-up solutions. Throughout the session we'll specifically look at some of the new features in WCF 4.0 and WCF Data Services.

1. Building RESTful Services with
WCF
Aaron Skonnard
Cofounder, Pluralsight

2. Overview

3. Why REST?

4. Why REST?
1. Most folks 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. REST is 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 not RPC
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 too simple for complex systems?

8. Why REST?
3. REST is 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
WCF doesn'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
Most of 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 HTTP GET 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 all other 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 to access 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 support for 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
Many features in the WCF REST Starter Kit are now part of WCF
4.0

20. Automatic help page
WCF 4 provides an automatic help page for REST services
Configure the <webHttp> behavior with helpEnabled=“true”

21. Message format selection
WCF 4 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
WCF 4 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
Download the 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