OWIN : From Spec to Application

Damian Hickey

@randompunter / dhickey.ie

dotned, 26 June 2014

> whoami

• Not a web or http expert!

My Pain

Web APPIIS

WindowsService

SQL Database

WCF

Everyone does their own thing

• ServiceStack Selfhost

• Nancy Selfhost

• WebAPI Selfhost

• WCF Selfhost

• OpenRasta Selfhost

• etc

The Plan

• Part 1: OWIN• Raison d'être

• Design goals

• The Specification

• Part 2: Implementations• Hosts & Middleware

• Testing

• Samples & Recipes

• Part 3: OWIN in the wild

Part 1 – OWIN

Open Web Interface for .NET

Prior Art

• System.Web• Complicated lifecycle• Doesn’t look like HTTP• Tied to IIS, in most part• Difficult to test• Doesn’t look like HTTP

• Web Forms (let’s not talk about that)

• MVC rests on same System.Web bits as Web Forms

• Python: Web Server Gateway Interface (WSGI)

• Ruby: Rack

• Java\Clojure: Ring

ASP.NET Life Cycle

(Browser)

What is OWIN?

• A specification, not a technology, created by the community

• Defines a standard, minimal, interface between .NET web servers and web applications

• Decouples server from applications / frameworks

Design Goals

• Super simple signature for Applications and Middleware

• Dependency free (library and config)

• Asynchronous and concurrent by design

• Respect HTTP – Requests, Responses, Headers and Streams

• Composable

Terminology

• Host

• Middleware

• Web Framework

• Web Application

• Process (aka Sever)

IISSystemWeb

Helios

HttpListener

WebListener

Nowin

HTTTP.SYS

SocketsKestrel (libuv)

NGIXApache(FastCGI

FIOS

OWIN (AppFunc)

Application- Nancy- WebAPI- Security- Compression- FileServer- WebSockets- MVC 6- Mapping- Limiting- StatusCodeHandling- ViewEngines- Routing- etc

Headers

Request Stream

Body Stream

Headers

Response Stream

Body Stream

OWIN

The Core – The Application Function• Aka “AppFunc”

• That’s it!

App

The Environment Dictionary

• IDictionary<string, object>

• Has a set of well-defined keys and value types

• Stores Request & Response data

• Is mutable

The Environment(Browser, owin.org)

Middleware

Middleware is a pipeline

Middleware Middleware

Middleware

Some Rules

• Http pipelining is handled by the server. Do not respond with 100 Continues

• Never close the response body stream

• Always complete the Task

Code

(VS)

Testing

Resources

• owin.org

• katanaproject.codeplex.com

• #owin chat room on jabbr.net

• .NET HTTP Abstractions google group

• github.com/owin