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Building HTTP Services with ASP.NET Web API
Sayed Ibrahim HashimiProgram ManagerMicrosoft Corporation
DEV309
What is a Web API?
An HTTP service
Designed for broad reach
Uses HTTP as an application protocol, not a transport protocol
Why build Web APIs?
Why build Web APIs?
Reach More Clients
Why build Web APIs?
Scale with the Cloud
Why build Web APIs?
Embrace HTTP
GET /en/html/dummy.php?name=MyName&married=not+single &male=yes HTTP/1.1Host: www.explainth.atUser-Agent: Mozilla/5.0 (Windows;en-GB; rv:1.8.0.11) Gecko/20070312 Firefox/1.5.0.11Accept: text/xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5Accept-Language: en-gb,en;q=0.5Accept-Encoding: gzip,deflateAccept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7Keep-Alive: 300Connection: keep-aliveReferer: http://www.explainth.at/en/misc/httpreq.shtml
demo
Sayed Ibrahim HashimiProgram ManagerMicrosoft Corporation
Contact Manager browser and mobile app
Web API framework requirements
Need a first class HTTP programming model
Easily map resources to URIs and implement the uniform interface
Rich support for formats and HTTP content negotiation
Separate out cross cutting concerns
Light weight, testable, scales
So you want to create a Web API . . .
?ASP.NET MVC
WCF Web HTTPWCF REST Starter KitWCF Web API
So you want to create a Web API . . .
+ASP.NET MVC
WCF Web HTTPWCF REST Starter KitWCF Web API
So you want to create a Web API . . .
ASP.NET Web API
ASP.NET Web API Features
From ASP.NET MVC
ASP.NET RoutingModel bindingValidationFiltersLink generationTestabilityIoC integrationVS templateScaffolding
From WCF Web API
Modern HTTP programming modelHttpClientTask-based asyncFormatting, content negotiationServer-side query compositionCreate custom help pagesSelf-hostTracing
http://www.asp.net/web-api
We are open source!http://aspnetwebstack.codeplex.com
demo
Sayed Ibrahim HashimiProgram ManagerMicrosoft Corporation
Your First Web API
To implement a Web API . . .
Derive from ApiController
Implement your actionsActions map to HTTP methods
Prefix method name with desired HTTP method – PostComment
Use [HttpGet/Post/Put/Delete] if you prefer a different name
Routing
Maps a URI space to your ApiControllersEx. api/{controller}/{id}
{controller} + “Controller” = ApiController type name
Can be tailored using default values and route constraints
Default Web API route
routes.MapHttpRoute(
name: "DefaultApi",routeTemplate: "api/{controller}/{id}",defaults: new { id = RouteParameter.Optional });
Action parameters
Simple types are taken from the URIRoute data, query parameters
Complex types come from the bodyConfigured MediaTypeFormatters are used to deserialize the request body based on the content type
JSON, XML, and form-url-encoded supported out of the box
Override using [FromUrl], [FromBody], [ModelBinder], custom parameter binding
Validation
Validation is run on the data from every requestValidation errors are accumulated in the ModelStateCheck ModelState.IsValidUses DataAnnotations or custom validation logic
Content Negotiation
Response format is determined based on HTTP content negotiation
Accept header in request expresses desired format(s)
Server selects a format for the response based on the:
Request
Action return type
Configured MediaTypeFormatters
JSON and XML supported out of the box
Content Negotiation
// Get the IContentNegotiator
IContentNegotiator negotiator = Configuration.Services.GetContentNegotiator();
// Run content negotiation to select a formatter
MediaTypeHeaderValue mediaType;
MediaTypeFormatter formatter = negotiator.Negotiate(
typeof(Contact), Request, Configuration.Formatters, out mediaType);
// Create a response message with an object content using the selected formatter
HttpResponseMessage response = new HttpResponseMessage()
{
Content = new ObjectContent<Contact>(contact, formatter),
RequestMessage = Request
};
Content Negotiation
HttpResponseMessage response =
Request.CreateResponse<Contact>(HttpStatusCode.Created, contact);
demo
Sayed Ibrahim HashimiProgram ManagerMicrosoft Corporation
Scaffolding an EF-based web API
Filters
Filters are used to handle cross cutting concerns
Filter types:Action filters run before and after invoking an action
Authorization filters run before model binding and are specifically for authorizing the user
Exception filters handle generating responses for error cases in a centralized way
Filters can be configured globally, per controller, or per action as an attribute
HTTP DispatcherInvoke Action
Action filters
Model Bind
Select action Exception filters
Route to controller Formatting
Request Response
Authorization filters
OData queries
Support for OData URL query syntax$top, $skip, $orderby, $filter
Enable query using [Queryable] filter and returning IQueryable<T> from a method
Orthogonal to format and content negotiation
demo
Sayed Ibrahim HashimiProgram ManagerMicrosoft Corporation
OData query support
HTTP request/response handling
Http Clien
t
HttpClient
Handler
Host Http
Dispatcher
Http Server
Message handlers Message handlers
Message handlers:Task<HttpResponseMessage> SendAsync(
HttpRequestMessage request,
CancellationToken cancellationToken)
demo
Sayed Ibrahim HashimiProgram ManagerMicrosoft Corporation
URI format extensions
Web API description
Use the IApiExplorer service to get a runtime description of the Web APIUseful for building custom help pages, test clients, and tooling
IApiExplorer
IApiExplorer apiExplorer =
config.Services.GetApiExplorer();
public interface IApiExplorer{Collection<ApiDescription> ApiDescriptions { get; }
}
demo
Sayed Ibrahim HashimiProgram ManagerMicrosoft Corporation
Custom web API help page
Hosting
Two hosting options todayASP.NET Web Application (IIS)Self-host server option (ex. console application, Windows service, Azure Worker Role, etc.)
HttpConfiguration is the common denominatorHost in memory for end-to-end testingUse an OWIN bridge to host on any OWIN compatible web server
demo
Sayed Ibrahim HashimiProgram ManagerMicrosoft Corporation
Flexible hosting
The Road Ahead
ASP.NET Web API ships with ASP.NET MVC 4
Supported on .NET 4
Ships in the box with Visual Studio 2012
Release Candidate available via Web Platform Installer, NuGet, Visual Studio 2012 RC
Summary
ASP.NET Web API in MVC 4 makes it easy to build HTTP services that can reach a broad set of clients
ASP.NET Web API is an ideal platform for creating RESTful services
Try out the ASP.NET MVC 4 Release Candidate
Follow our progress on CodePlex
Related Content
DEV301 ASP.NET Roadmap: One ASP.NET – Web Forms, MVC, Web API, and more
DEV302 What's New in Visual Studio 2012 for Web Developers
DEV303 ASP.NET Loves HTML5
DEV304 ASP.NET for Mobile and Tablet Development
DEV305 Microsoft ASP.NET and the Realtime Web
DEV Track Resources
Visual Studio Home Page :: http://www.microsoft.com/visualstudio/en-us
Jason Zander’s Blog :: http://blogs.msdn.com/b/jasonz/
Facebook :: http://www.facebook.com/visualstudio
Twitter :: http://twitter.com/#!/visualstudio
Somasegar’s Blog :: http://blogs.msdn.com/b/somasegar/
Resources
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Learning
Microsoft Certification & Training Resources
www.microsoft.com/learning
TechNet
Resources for IT Professionals
http://microsoft.com/technet
Resources for Developers
http://microsoft.com/msdn
Evaluations
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Submit your evals online
© 2012 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.
Why build Web APIs?
