ASP.NET Web API Udaiappa Ramachandran NHDN-Nashua.NET/Cloud Computing UG Lead Blog:

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

Demo: Web API Basics

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

Demo: Web API Routing

Filtering  Uses OData specific keywords $expand Directs that related records should be retrieved in the record or collection being retrieved. $filter Specifies an expression or function that must evaluate to ‘true’ for a record to be returned in the collection. $orderbyDetermines what values are used to order a collection of records. $selectSpecifies a sub set of properties to return. $skipSets the number of records to skip before it retrieves records in a collection. $topDetermines the maximum number of records to return. Install-Package Microsoft.AspNet.WebApi.OData -Pre

Demo: Web API Filtering

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

Pipeline Elements

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

Demo: Self Hosting

Resource    Host-30abca12 Host-30abca12   net-web-api-and-httpclient-samples.aspx net-web-api-and-httpclient-samples.aspx

Q & A