Web api

ASP.NET Web API

Udaiappa Ramachandran
NHDN-Nashua .NET/Cloud Computing UG Lead
Email: udaiappa@gmail.com
Blog: http://cloudycode.wordpress.com

Agenda
 Introduction to Web API
 Web API Routing
 Web API Pipeline
 Dependency Injections and Resolvers
 Model Binding and Media Formats
 Self Hosting
 Deploying Web API into cloud
 References

Introduction to Web API
 Next iteration of WCF REST
 Framework for developing REST Services
 Released part of ASP.NET MVC
 Uses HTTP protocol
 Accessible from wide variety of clients
 Http Methods: GET, POST, PUT, DELETE
 URLs and Methods

Web API Routing
 Web API Routing very similar to MVC routing
 Action determined using the HTTP method not the URI path
 Uses “api” in the rout is to avoid collisons with ASP.NET MVC
routing.
 Adds “Controller” to the controller part of the URL
 Default mapping thru global.asax
 Additional URL parameters are mapped as action parameters
 Explicitly specify the HTTP methods for an action by decorating
the action method with HttpGet, HttpPut, HttpPost or
HttpDelete attribute
 Action can be defined thru AcceptVerbs as a method attributes
 Route by Action Name
 Override action name by using ActionName attribute
 Ignore action by NoAction Attribute

Filtering
 Uses OData specific keywords
Directs that related records should be retrieved in the record or collection
$expand
being retrieved.
Specifies an expression or function that must evaluate to ‘true’ for a record to
$filter
be returned in the collection.

$orderby Determines what values are used to order a collection of records.

$select Specifies a sub set of properties to return.

$skip Sets the number of records to skip before it retrieves records in a collection.

$top Determines the maximum number of records to return.

Install-Package Microsoft.AspNet.WebApi.OData -Pre

Web API Pipeline
 Both Request and Response Model have pipeline
 Web API has client and server side pipelines
 Both Share the common object HttpMessageHandler
 HttpRequestMessage
 Represents all info about http request such as URL, HTTP Methods and
Headers
 HttpResponseMessage
 Represents all the info about the Http Response such as StatusCode,
Success Flag, Original Http Request
 HttpMessageHandler
 Common for both Request and Response
 Most common processing code can be placed here
 Ideal for authentication
 Two Scopes: Global and Per-Route
 Custom Handlers
 Inherit DelegatingHandler
 Custom code to perform any kind of per request functionality

Demo: Web API Pipeline
Demo: Custom Handlers

Dependency Resolution
 Service Oriented Architecture for Decoupling the
object
 IoC: The concept of allowing something outside of
system to control it.
 Often done thru DI frameworks
 Unity
 Ninject
 Castle Windsor
 Structure Map
 Spring.net
 Autofac
 Web API provides a hook for us to wire up the
complex dependency

Demo: Simple Resolver
Demo: Resolve using DI Framework

Data Model and MIME types
 Returning JSON
 Default return format
 Good for mobile apps
 does not require any special code
 Returning XML
 No code change
 Set the request content type as application/xml
 Mime Types:
 return virtually anything that can be sent over the web
 Inherit from BufferedMediaTypeFormatter
 Override key methods
 attach media formatter to configuration

Demo: Data Model
Demo: MIME Types

Hosting
 IIS
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

 Self Hosting
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
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Resource
 http://cloudycode.wordpress.com
 http://www.asp.net/web-api/overview
 http://code.msdn.microsoft.com/ASPNET-Web-API-Self-
Host-30abca12
 http://msdn.microsoft.com/en-us/library/gg309461.aspx
 http://blogs.msdn.com/b/webdev/archive/2012/08/26/asp-
net-web-api-and-httpclient-samples.aspx

Web api

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