Creating a RESTful API with WCFAaron Sloman, speakTECHHaider Sabri, speakTECH

About this presentation…

BackgroundREST (Representational State Transfer)

What does it mean to be RESTful?Why REST?

WCFHow does WCF support REST?What are the pieces we need to add?

ChessA RESTful Chess API

Background

Open Your API – 2005MySpace API roadmapWhere are we today ?

developer.myspace.com

Requirements for the Service

Public interface for 3rd party clients and partners to view, add, update, delete data.Easily consumable by any clientFollows established industry standardsNeeds to be highly scalableSupports different data interchange formatsModerately securable

Solution

Test’s we did….

WCFREST

Resource Oriented ArchitectureWhat does it mean to be RESTful?Power combo: URI and HTTP Method

Addressable, hierarchical URIs represent the entities or objects on your APIHTTP Method represents the action to be taken on the resource

Connectedness and DiscoverabilityLike the Web, Http Responses contain links to other resources

Roy Fielding dissertation http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm

Why REST?

Benefits of REST for Web APIsLow barrier of entryROA follows Web Semantics…convenient for Web Service APIs.Flexibility in Response formats

REST is best choice when creating a general API when clients are unknown

A RESTful API in Action

demo

WCF Support for ROAThe “Web Programming Model”

URI Templates & WebGet/WebInvokeAttribute based definitions of URI template and HTTP method provide mapping of incoming request URIs to methods

WebHttpBindingThe binding that enables above

WebOperationContextFor more information:

Building Applications and Services with .NET Framework 3.5San Polo 3501A, M10:15 AM March 6th

RESTChess behind the scenes…RESTChess.com

demo

The pieces we need to addThe 20%

Flexible URIsBridging Low REST clientsRequest Authentication via Digital SigningExtending WebOperationContextMultiple Representation FormatsRESTful Exception Handling

URI Template shortcomingsProblems…

Service .svc extensionRequired when hosting a WCF service in IIS

Can’t use custom extensions in templates

What if I want to let the URI extension define the representation format?

URI Template shortcomingsSolutions…

Use URL Rewriter implemented as an HttpModule

Add .svc service file to incoming request URIUse extension format in path hierarchy and rewrite URI accordingly

URLRewriting via IIS7

demo

High/Low REST with the same service

High: support for full set of HTTP methodsLow: only support GET and POSTAllow clients to override HTTP method

Using X-HTTPMethodOverride headerUse of _method query parameter

Extending WCF…Channels to the Rescue

High/Low REST

Extending WCF via Custom Channel

demo

Request AuthenticationOAuth

Introducing OAuthStandards based API authentication

Standard access delegation between Consumer and ProviderStandard digital signing mechanismoauth.net

Request AuthenticationOAuth

WCF Custom Channels to the rescue again

Channel will authenticate request before method dispatch

Extend Context with application data

OAuth

Extending WCF via Custom Channel

demo

RIA consumes RestChess

demo

Summary

MySpace Development Platform is RESTfulWCF is a powerful web API development platformWCF has great extension pointsAll demo source available at RestChess.com

MySpace API’s are availableVisit developer.myspace.com

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