Introduction to ASP.NET MVC Blogging Engine in 60 minutes

Adnan Masoodwww.AdnanMasood.comwww.CodePlex.com/YABE

About Meaka. Shameless Self Promotion

• Sr. Software Engineer / Tech Lead for Green Dot Corp. (Financial Institution)

• Design and Develop Connected Systems• Involved with SoCal Dev community, co-founded San Gabriel Valley .NET

Developers Group. Published author and speaker.• MS. Computer Science, MCPD (Enterprise Developer), MCT, MCSD.NET• Doctoral Student - Areas of Interest: Machine learning, Bayesian

Inference, Data Mining, Collaborative Filtering, Recommender Systems.• Contact at adnanmasood@acm.org• Read my Blog at www.AdnanMasood.com• Doing a session in IASA 2008 in San Francisco on Aspect Oriented

Programming; for details visit http://www.iasaconnections.com

YABEYet another blogging engine

• Team– Adnan Masood– Jeff Bergman– Sean Xiao

• www.CodePlex.com/YABE• Uses Linq to SQL for data access• Syndication Libraries for the RSS/Atom Feeds• Experiment in learning MVC

Latest Developments in the MVC world

• Scott Guthrie, adaptation from RoR• How does this relate to Visual Studio 2008/.NET 3.5 SP1 Beta?• It doesn't. For now ASP.NET MVC is an out-of-band Web

downloadable thing. It's bin deployable (meaning you don't HAVE to put them in the GAC) and you don't even need to tell your hosting/ISP. They are what they are - three DLLs in a folder. Bam.

• MVC Preview 3 will not be affected by having SP1 installed. Preview 3 will include newer privately versioned bin deployable builds of the Routing and Abstractions DLLs. That way these assemblies will not be affected by the versions in the GAC installed by SP1, because they will have different version numbers.

MVC vs. “Classic” ASP.NET

Ok, so what is this MVC thingy?• It is an ASP.NET framework that performs data exchange by using

a REST model versus the postback model of classic ASP.NET. Each page is split into two distinct components -controller and view - that operate over the same model of data. This is opposed to the classic code-behind model where no barrier is set that forces you to think in terms of separation of concerns and controllers and views. However, by keeping the code-behind class as thin as possible, and designing the business layer appropriately, a good developer could achieve separation of concerns even without adopting MVC and its overhead. MVC, however, is a model superior to a properly-done code-behind for its inherent support for test-driven development.

Model View Controller Pattern

More Concrete Model View Controller Pattern

Why use ASP.NET MVC?• It enables clean separation of concerns, testability, and TDD by default. All core contracts within the MVC

framework are interface based and easily mockable (it includes interface based IHttpRequest/IHttpResponse intrinsics). You can unit test the application without having to run the Controllers within an ASP.NET process (making unit testing fast). You can use any unit testing framework you want to-do this testing (including NUnit, MBUnit, MS Test, etc).

• It is highly extensible and pluggable. Everything in the MVC framework is designed so that it can be easily replaced/customized (for example: you can optionally plug-in your own view engine, routing policy, parameter serialization, etc). It also supports using existing dependency injection and IOC container models (Windsor, Spring.Net, NHibernate, etc).

• It includes a very powerful URL mapping component that enables you to build applications with clean URLs. URLs do not need to have extensions within them, and are designed to easily support SEO and REST-friendly naming patterns. For example, I could easily map the /products/edit/4 URL to the "Edit" action of the ProductsController class in my project above, or map the /Blogs/scottgu/10-10-2007/SomeTopic/ URL to a "DisplayPost" action of a BlogEngineController class.

• The MVC framework supports using the existing ASP.NET .ASPX, .ASCX, and .Master markup files as "view templates" (meaning you can easily use existing ASP.NET features like nested master pages, <%= %> snippets, declarative server controls, templates, data-binding, localization, etc). It does not, however, use the existing post-back model for interactions back to the server. Instead, you'll route all end-user interactions to a Controller class instead - which helps ensure clean separation of concerns and testability (it also means no viewstate or page lifecycle with MVC based views).

• The ASP.NET MVC framework fully supports existing ASP.NET features like forms/windows authentication, URL authorization, membership/roles, output and data caching, session/profile state management, health monitoring, configuration system, the provider architecture, etc.

Why MVC is so different?

• REST is an architectural pattern that defines how network resources should be defined and addressed in order to gain shorter response times, clear separation of concerns between the front-end and back-end of a networked system. REST is based on three following principles:

• An application expresses its state and implements its functionality by acting on logical resources

• Each resource is addressed using a specific URL syntax• All addressable resources feature a contracted set of

operations

The answer to Url’s Life, 42.

• In the MVC Framework, a URL is seen as the mean to address a logical server resource, but not necessarily an ASPX file to parse. So the URLs employed by the pages of an MVC Framework application have a custom format that the application itself mandates. In the end, the MVC Framework employs a centralized HTTP handler that recognizes an application-specific syntax for links. In addition, each addressable resource exposes a well-known set of operations and a uniform interface for executing operations.

What? No more postbacks!

• The MVC Framework doesn't support classic postbacks and viewstate and doesn't consider any URL as the endpoint to a physical server file to parse and compile to a class. In ASP.NET, you have a 1:1 correspondence between a URL and a resource.

Why MVC? (links)

• The REST-like Aspect of MVC Framework• ASP.NET MVC Framework: An early look• RSS Feed with the new ASP.NET MVC Framewo

rk• MVC, REST, and the Alternative ASP.NET Frame

work• ASP.NET MVC framework - ready or not

Why MVC?

• Very Clean separation of Concerns• Unit Testing• Model that leads you down a maintainable

path (prevent crappy code)• Clean Urls and Html

Front Controller

• Classic asp.net framework is Page Controller• Map Urls to classes/controllers instead of

Pages

Unit Testing

• Mock Objects to simulate responses.• Don’t have to go through a page or view• Red/Green Testing

Unit Testing

• Create instance of controller• controller.ViewEngine = new TestViewEngine();• Uses Mock Objects

Features

• Routing• Controller• View• Dependency Injection• Pluggable• Interfaces for all core contracts

Url

• Url no longer points to the view/aspx page• A Url maps to a controller class• Allows more flexibility to map Urls• Url routing engine, Route table• Routes are tokenized strings• Can use RegEx

Route Examples

• <Controller>/<Action>/<Param>• http://domain/Home/CustomerDetail/45• Html.Link for creating outbound urls• Html.Link(<Friendly Name>, <Action>,

<Controller>)

Controller

• IController• Execute(IHttpContext ctx, RouteData

routeData)• class MyController : Controller• [ControllerAction] attribute

View

• Similar to existing page• No postback or view state• Not all page events will fire• Editing forms will be more work• Separate page for viewing, editing, and updating• Ajax will use UserControls as update panels butrequest still goes through the control

Views

• View probably shouldn’t directly access data sources or services.

• Use the ViewData which stores the model the view is rendering

• ViewPage<T>, ViewPage

Future of the ASP.NET MVC

• MVC for the Enterprise• Classic Asp.Net for quicker implementations

References

• Download the Latest MVC Preview 3http://www.microsoft.com/downloads/details.aspx?FamilyId=92F2A8F0-9243-4697-8F9A-FCF6BC9F66AB&displaylang=en

• ASP.NET MVC Preview 3http://www.hanselman.com/blog/ASPNETMVCPreview3.aspx

• Quick Start Guideshttp://quickstarts.asp.net/3-5-extensions/mvc/default.aspx

• Upcoming Changes in Routinghttp://haacked.com/archive/2008/04/10/upcoming-changes-in-routing.aspx

• Scott Guthrie’s Post on ASP.NET MVC Frameworkhttp://weblogs.asp.net/scottgu/archive/2007/10/14/asp-net-mvc-framework.aspx

Questions?• ASP.NET MVC is a new paradigm for .NET Developers; a new way

to think about programming web application.• Any Questions / Comments … feel free to contact

adnanmasood@gmail.com • Visit www.CodePlex.com/YABE• Visit www.AdnanMasood.com