A brief introduction to OWIN and Katana, the basics and few basic details on the analysis of the internal workings of OWIN and functions, the middleware registrations and how they all compare to the traditional request processing pipelines.

1. INTRODUCTION TO OWIN
Saravanan

2. AGENDA
 OWIN Introduction
 OWIN and Katana
 Inspiration
 Architecture
 Application Startup & Registrations
 Hosting Methods
 Servers
 Request processing Pipelines
 Modules / Middlewares
 Hosting
 OWIN IIS Pipeline
 OWIN Self-Hosting

3. OWIN & KATANA
 Open web Interface for .Net
 Spec is here
 Katana: A Microsoft implementation of OWIN
 Not a replacement for ASP.Net / SignalR or WebAPI.
Just offers hosting methods.
 Reduced interaction between the server and the
applications
 Application delegate:
Func<IDictionary<string, object>, Task>

4. INSPIRATION
 RACK
 Rack provides a minimal, modular and adaptable
interface for developing web applications in Ruby. By
wrapping HTTP requests and responses in the simplest
way possible, it unifies and distills the API for web
servers, web frameworks, and software in between (the
so-called middleware) into a single method call
 Node.js
 Node.js is a platform built on Chrome's JavaScript
runtime for easily building fast, scalable network
applications. Node.js uses an event-driven, non-
blocking I/O model that makes it lightweight and
efficient, perfect for data-intensive real-time applications
that run across distributed devices.

5. INTRODUCTION
 Minimal, modular and adaptable interface for
developing web applications
 Exposes a wrapper for Http requests and http
responses
 Single method call to handle
 Web Servers
 Middleware
 Web Applications

6. OWIN
 To decouple server and the web applications
 Defines the structure and requirements of HTTP
request and response interactions
 Support for applications in any platform
Example
 Kayak => runs on nix systems using Mono

7. ARCHITECTURE
Application: Because Katana is not a replacement for
ASP.NET but rather a new way to compose and host
components, existing ASP.NET Web API and SignalR
applications remain unchanged, as those frameworks can
participate in an OWIN pipeline. In fact, for these kinds of
applications, Katana components will be visible only in a small
configuration class.
Middleware: The name given to all of the components that
handle requests in an OWIN pipeline. It can range from a
simple compression component to a complete framework such
as ASP.NET Web API, though from the server’s perspective, it’s
simply a component that exposes the application delegate.
Server: Responsible for binding to a TCP port, constructing the
environment dictionary and processing requests through an
OWIN pipeline.
Host: The process that runs the application. Can IIS or
standalone executable. The host is responsible for startup,
loading of other OWIN components and shutting down
gracefully.

8. ARCHITECTURE CONTD..,

9. APPLICATION START-UP
 IDictionary<string, object> creation and populates any
startup data or capabilities provided by the host.
 Server selection [owinhost or iis]
 Location of the application setup code and invokes it
with the Properties collection.
 Reads and/or sets configuration in the Properties
collection, constructs the desired request processing
pipeline, and returns the resulting application delegate.
 Invokes the server startup code with the given
application delegate and the Properties dictionary.
 The server finishes configuring itself, starts accepting
requests, and invokes the application delegate to
process those requests.

10. REGISTRATION
 Uses the Pre-Application Start to configure OWIN

11. HOSTING METHODS
Details IIS Pipeline
Integration
OWIN pipeline
Supported by IIS Katana.exe
Modules HttpModules OMC [OWIN
middleware
Components]
OWIN Startup Via OwinHttpModule Startup
Stage based code
plugin
Via IIS pipeline stages Via Stage markers

12. SERVER
 IIS
 OwinHost
 CustomServers

13. WHY HAVE PIPELINES [SOC]
 Authentication: Plug-in various authentication
mechanisms. How do I validate this OAuth, HTTP
Basic Authentication, name/password?
 Authorisation: "is the user authorized to perform
this particular task?", i.e. role-based security.
 Caching: have I processed this request already,
can I return a cached result?
 Performance & Usage Monitoring: what stats can
I get from the request and response?
 Execution: actually handle the request and provide
a response.

14. OWIN / IIS PIPELINE STAGES
OWIN Pipeline Stages IIS Pipeline Stages

15. TRADITIONAL IIS HTTPMODULE

16. OWIN MIDDLEWARE COMPONENTS [OMC]

17. OWIN MIDDLEWARE
 Grouping and ordering of the modules
 Are run for each request
 Similar to that of a HttpMessageHandler
[subscribes to each request]
Sample Middlewares
 Static file renderers
 WebAPI
 Nancy [web framework for mono]

18. ENVIRONMENT
 All states, including
 application state,
 request state,
 server state etc,
 are held in the IDictionary<string, object> object
specified on the application delegate.
 This is passed from component to component as a
request progresses through the pipeline
 No specific .NET object model, such as those of
HttpContextBase in ASP.NET MVC or
HttpRequestMessage/HttpResponseMessage in
ASP.NET Web API

19. OWIN IIS PIPELINE

20. OWIN SELF-HOST

21. MORE INFORMATION
 OWIN: http://owin.org/
 OWIN Spec: http://owin.org/spec/owin-1.0.0.html
 Katana: https://katanaproject.codeplex.com/
 Katana Documentation:
https://katanaproject.codeplex.com/documentation

22. Thank you