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Introducing ASP.NET MVC

Introducing ASP.NET MVC. Alan Dean, Senior Technologist. Model-View-Controller (MVC) is a well-known design pattern The original 1978 implementation is described in depth in the influential 1992 paper “Applications Programming in Smalltalk-80: How to use Model-View-Controller (MVC)”

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Introducing ASP.NET MVC

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  1. Introducing ASP.NET MVC Alan Dean, Senior Technologist

  2. Model-View-Controller (MVC) is a well-known design pattern The original 1978 implementation is described in depth in the influential 1992 paper “Applications Programming in Smalltalk-80: How to use Model-View-Controller (MVC)” by Steve Burbeck

  3. …“the concept of the design pattern in software provides a key to helping developers leverage the expertise of other skilled architects.” Grady Booch, 1995

  4. MVC consists of three kinds of objects • The Model is the application object • The View is the screen presentation • The Controllerdefines the way the user interface reacts to user input

  5. Before MVC, user interface designs tended to lump these objects together MVC decouples them to increase flexibility and reuse

  6. Model View Controller

  7. In his paper Steve Burbeck describes two variations of MVC a passive model and an active model

  8. The passive model is employed when one controller manipulates the model exclusively The controller modifies the model and then informs the view that the model has changed and should be refreshed The model in this scenario is completely independent of the view and the controller, which means that there is no means for the model to report changes in its state

  9. Controller View Model handleEvent service update getData

  10. The HTTP protocol is an example of this. The browser displays the view and responds to user input, but it does not detect changes in the data on the server. Only when the browser explicitly requests a refresh is the server interrogated for changes.

  11. Separation of Concerns (SoC) • Object types become ‘pluggable’ • Intra-team dependency is reduced • Testability is enhanced • Application flow can be hard to grok

  12. MVC Web Frameworks • Java has Swing, Struts, Grails and others • Perl has Catalyst, Gantry, Jiftyand others • PHP has Zend, Zoop, Agavi and others • Python has Django, Gluon, Pylon and others • Ruby on Rails is famously ‘opinionated’ • … and .NET?

  13. .NET MVC Web Frameworks • Spring.NET • http://www.springframework.net/ • Maverick.NET • http://mavnet.sourceforge.net/ • MonoRail • http://www.castleproject.org/monorail/ • … and now ASP.NET MVC from Microsoft • http://asp.net/downloads/3.5-extensions/

  14. “The ASP.NET MVC framework is a lightweight, highly testable presentation framework that is integrated with existing ASP.NET features, such as master pages and membership-based authentication. The MVC framework is defined in the System.Web.Mvc namespace and is a fundamental, supported part of the System.Web namespace”

  15. Demo Create a new ASP.NET MVC Solution

  16. HTTP Request Flow HTTP Request Route Handler Controller Model View HTTP Response GET /Home/Index HTTP/1.1

  17. HTTP Request Flow HTTP Request Route Handler Controller Model View HTTP Response public classGlobal : HttpApplication { protected voidApplication_Start(object sender, EventArgs e) { RouteTable.Routes.Add(newRoute { Url = "[controller]/[action]/[id]", Defaults = new { action = "Index", id = (string)null }, RouteHandler = typeof(MvcRouteHandler) }); } }

  18. HTTP Request Flow HTTP Request Route Handler Controller Model View HTTP Response public classHomeController : Controller { [ControllerAction] public void Index() { CompanyInfocompanyInfo = newCompanyInfo(); companyInfo.CompanyName = "Your company name here"; RenderView("Index", companyInfo); } }

  19. HTTP Request Flow HTTP Request Route Handler Controller Model View HTTP Response public classCompanyInfo { public stringCompanyName { get; set; } }

  20. HTTP Request Flow HTTP Request Route Handler Controller Model View Response public partial classIndex : ViewPage<CompanyInfo> { } <%@ PageLanguage="C#" AutoEventWireup="true" CodeBehind="Index.aspx.cs" Inherits="MvcApplication.Views.Home.Index" %> <html> <head> <title><%= this.ViewData.companyName %></title> </head> <body> <%= Html.ActionLink(“Homepage", "Index", "Home") %> <div>Welcome!</div> </body> </html>

  21. HTTP Request Flow HTTP Request Route Handler Controller Model View HTTP Response HTTP/1.1 200 OK Content-Type: text/html <html> <head> <title>Your company name here</title> </head> <body> <a href="/Home/Index">Index</a> <div>Welcome!</div> </body> </html>

  22. Wiki A wiki is software that allows users to create, edit, and link web pages easily

  23. Ward Cunningham, developer of the first wiki, WikiWikiWeb, originally described it as "the simplest online database that could possibly work"

  24. Wiki Database CREATE TABLE [dbo].[PageTable] ( [Id] int IDENTITY(1,1) NOT NULL, [Guid] uniqueidentifier NOT NULL, [LastModified] datetime NOT NULL, [Removed] datetime NULL, [Title] varchar(255) NOT NULL, [Body] ntext NOT NULL );

  25. Wiki HTTP API GET / GET /page.html POST /page GET /page/[title] GET /page/[title].txt GET /page/[title].html GET /page/[title].atom PUT /page/[title] DELETE /page/[title]

  26. GET • The GET method means retrieve whatever information (in the form of an entity) is identified by the Request-URI. • Safe & Idempotent

  27. GET / Accept: text/html, */* 303 See Other Location: http://localhost/page.html Cache-Control: public Expires: Thu, 31 Jan 2008 16:00:00 GMT

  28. GET /page.html Accept: text/html, */* 200 OK Content-Type: text/html Cache-Control: public Expires: Thu, 31 Jan 2008 16:00:00 GMT <html> <head><title>…</title></head> <body> <form action="/page" method="post" enctype="application/x-www-form-urlencoded"> <input type="text" name="title" maxlength="255" /> <textarea name="body" rows="25" cols="80"></textarea> <input type="submit" value="Create Page" /> </form> </body> </html>

  29. POST • The POST method is used to request that the origin server accept the entity enclosed in the request as a new subordinate of the resource identified by the Request-URI

  30. POST /page Content-Type: application/x-www-form-urlencoded title=Welcome&body=Welcome+to+my+new+wiki. 201 Created Content-Type: text/html Content-Location: http://localhost/page/Welcome Cache-Control: no-cache <html> <head> <title>…</title> <meta http-equiv="refresh" content="0;url=http://localhost:64701/page/Welcome"> </head> <body>…</body> </html>

  31. GET /page/Welcome Accept: text/html, */* 303 See Other Location: http://localhost/page/Welcome.html Cache-Control: public Last-Modified: Tue, 29 Jan 2008 16:00:00 GMT Vary: Accept

  32. GET /page/Welcome.html Accept: text/html, */* 200 OK Content-Type: text/html Content-Location: http://localhost/page/Welcome Cache-Control: public Last-Modified: Tue, 29 Jan 2008 16:00:00 GMT <html> <head> <title>…</title> <link href="http://localhost/page/Welcome.atom" rel="alternate" title="…" type="application/atom+xml" /> </head> <body>…</body> </html>

  33. GET /page/Welcome.atom Accept: application/atom+xml 200 OK Content-Type: application/atom+xml Content-Location: http://localhost/page/Welcome Cache-Control: public Last-Modified: Tue, 29 Jan 2008 16:00:00 GMT <?xml version="1.0" encoding="utf-8”?> <feed xml:lang="en" xmlns="http://www.w3.org/2005/Atom"> … <link href="http://localhost:64701/page/Welcome" rel="source" /> <link href="http://localhost:64701/page/Welcome.atom" rel="self" type="application/atom+xml" hreflang="en" title="…" /> <link href="http://localhost:64701/page/Welcome.html" rel="alternate" type="text/html" hreflang="en" title="…" /> <link href="http://localhost:64701/page/Welcome.txt" rel="alternate" type="text/plain" hreflang="en" title="…" /> <entry>…</entry> </feed>

  34. GET /page/Welcome Accept: text/plain 303 See Other Location: http://localhost/page/Welcome.txt Cache-Control: public Last-Modified: Tue, 29 Jan 2008 16:00:00 GMT Vary: Accept GET /page/Welcome.txt Accept: text/plain 200 OK Content-Type: text/plain Content-Location: http://localhost/page/Welcome Cache-Control: public Last-Modified: Tue, 29 Jan 2008 16:00:00 GMT Welcome to my new wiki.

  35. PUT • The PUT method requests that the enclosed entity be stored under the supplied Request-URI. • If the Request-URI refers to an already existing resource, the enclosed entity SHOULD be considered as a modified version of the one residing on the origin server. • Idempotent

  36. PUT /page/Welcome Content-Type: text/plain Welcome to my new [[wiki]]. 204 No Content Cache-Control: no-cache

  37. DELETE • The DELETE method requests that the origin server delete the resource identified by the Request-URI. • Idempotent

  38. DELETE /page/Welcome 204 No Content Cache-Control: no-cache

  39. REpresentationalState Transfer

  40. REST: The Web Used Correctly • A system or application architecture • … that uses HTTP, URI and other Web • standards “correctly” • … is “on” the Web, not tunnelled through it

  41. REST is an Architectural Style • Defines a set of key “constraints” • … that, if met, make an architecture “RESTful” • … with the Web as one example

  42. Equate “REST” with “RESTful HTTP usage” Stefan Tilkov

  43. Deriving REST • Client-Server • Stateless • Cache • Uniform interface • Layered system • Code on Demand

  44. “The central feature that distinguishes the REST architectural style from other network-based styles is its emphasis on a uniform interface between components.” Roy Fielding

  45. Uniform Interface • Uniform resource identification • A set of well-defined operations for manipulation • A shared set of media-types • Hypertext as the engine of application state

  46. Benefits of REST • Hypertext is standardized • fewer UIs • Identification is standardized • less communication • Exchange protocols are standardized • fewer integrations • Interactions are standardized • fewer semantics • Data formats are standardized • fewer translations

  47. “No matter how hard I try, I still think the WS-* stack is bloated, opaque, and insanely complex. I think it is going to be hard to understand, hard to implement, hard to interoperate, and hard to secure.” Tim Bray (XML Co-inventor)

  48. “If you’re ready for REST I suggest you jump on board right away and get ahead of the curve You’ll have to train your developers in REST principles. You definitely need to provide guidance to your people. What you want to do is work to the point where REST becomes the default for all your distributed applications.” Anne Thomas Manes (Burton Group)

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