Castle

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Castle

• Manoj Waikar
• Pune, India.

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Introduction

• Castle aspires to simplify the development of
  enterprise and web applications.
  
• It offers a set of tools (working together or
  independently) and integration with other open
  source projects, thereby helping you get more
  done with less code.

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Castle Stack
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Different projects under Castle

• Rapid Web Application Development
• MonoRail
• Object Relational Database Mapping
• ActiveRecord The enterprise data mapping
  pattern implemented using Nhibernate.
• ActiveRecord Generator - A desktop application to
  generate ActiveRecord classes based on database
  schema.
• Inversion of Control Containers
• MicroKernel / Windsor Container
• Facilities
• Components
• Services
• contd...

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Different projects under Castle

• General Tools
• Dynamic Proxy
• Aspect Oriented Programming
• AspectSharp

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MonoRail

• MonoRail (formerly, Castle on Rails) is an MVC
  web framework inspired by Ruby on Rails.
• MonoRail differs from the standard WebForms way
  of development as it enforces separation of
  concerns controllers just handle application
  flow, models represent the data, and the view is
  just concerned about presentation logic.
  Consequently, you write less code and end up with
  a more maintainable application.
  contd...

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MonoRail How it works
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MVC in MonoRail

• MonoRail supports MVC out of the box. The
  following simple steps are needed to build a web
  application (that inherently uses the MVC
  pattern) -
• Map the extension .rails with IIS.
• Structure all the URLs as .../ltControllergt/ltAction
  Methodsgt.railse.g. http//localhost/intranet/hom
  e/index.rails
• Structure your (C) projects and solutions as -
• All the controllers in the Controllers
  sub-directory.
• All the views (.aspx or .rails) under a Views
  sub-directory.
• All the Master Pages under the /Views/Layouts
  sub-directory.
• All the rescues in the /Views/Rescues
  sub-directory.

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MonoRail Features

• Filters
• Filters are executed before and / or after your
  actions. It's useful for security, dynamic
  content and to keep away repetitive
  code. contd...

namespace Yournamespace public class
SecurityFilter IFilter public bool
Perform(ExecuteEnum exec, IRailsEngineContext
context, Controller controller) if
(context.Session.Contains("user"))
return true else
context.Response.Redirect("account", "login")
return false
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MonoRail Features

• contd...

Filter(ExecuteEnum.BeforeAction,
typeof(SecurityFilter)) public class
HomeController Controller public void
MyAction() SkipFilter public void
SomeOtherAction()
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MonoRail Features

• Rescues
• Rescue is a way to associate a nice page to
  display some nasty error information.
  contd...

Rescue("generalerror") public class
HomeController Controller public void
Index() Rescue("databaseerror")
public void Save()
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MonoRail Features

• Layouts
• Layouts allow you to build templates for your
  site by specifying common HTML and controls (such
  as structural HTML and navigation controls), in
  one place, that are available for any view to
  use.
• NVelocity Layouts
• There are other features too like Data Binding,
  support for AJAX, JavaScript validations.

Welcome! ltpgtchildContentlt/pgt Footer
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ActiveRecord

• ActiveRecord is a well-known pattern described in
  Patterns of Enterprise Application Architecture
  (by Martin Fowler). Basically all static methods
  act on the whole set of records, while instances
  represents each row.
• ActiveRecord is an implementation of the (above)
  ActiveRecord pattern for .Net.
• ActiveRecord uses NHibernate, but you don't need
  to write any fancy XML mapping as it handles
  everything for you. You just need to decorate
  your classes with attributes to declare behavior
  and meaning.

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ActiveRecord vs. NHibernate

• How does it differ from pure NHibernate usage?
• Fast development (it handles the mapping and
  infers as much as it can so you don't have to dig
  into documentation or deal with tons of xmls
  everytime something changes on your schema).
• Predefined common methods like Create, Update,
  Save, Delete.
• Easy to implement methods like Find, FindAll,
  FindByName etc.
• Session and transaction scopes that abstract the
  (NHibernate) ISession and translates it to a more
  natural idiom.

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ActiveRecord Generator

• ActiveRecord Generator is a desktop application
  that generates ActiveRecord classes (code) based
  on a database schema.
• It currently uses OleDb to extract the meta
  information and to infer the relationships.
• Currently works only with MS Sql Server.

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Inversion of Control

• A principle that dictates how you design and
  implement system components and their
  interdependencies in a way that decreases
  coupling.
• A principle that dictates that an external entity
  should send messages to programmer's objects in
  order to perform some specialised action or to
  allow the programmer to override some logic.
• The major difference between an object-oriented
  framework and a class library is that the
  framework calls the application code. Normally
  the application code calls the class library.
  This inversion of control is sometimes named the
  Hollywood principle, Do not call us, we call
  You. contd...

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MicroKernel / Windsor Container

• The MicroKernel offers an extensible inversion of
  control container core.
• The Windsor Container aggregates the MicroKernel
  providing a simpler interface and a set of
  important features that rely on MicroKernel
  extension points.
• The concern of the Windsor container is to offer
  a façade to the kernel and deal with external
  configuration, proxies and automatic
  component/facilities install.

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How to use...

• NOTE If you just need the container (no external
  configuration, no proxies) then MicroKernel is
  the right choice. However most common
  applications require the features that Windsor
  Container provides.The more straightforward
  usage is to instantiate the container and
  register the components
• and then to get the component

IWindsorContainer container new
WindsorContainer() container.AddComponent("mail",
typeof(IMailServer), typeof(SmtpMailServer))
SmtpMailServer instance containermail as
SmtpMailServer
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Dynamic Proxy

• The DynamicProxy project was created to overcome
  the CLR's proxy (in)capabilities. There are
  proxies in the CLR world, but they can be
  considered a bit intrusive as it forces one to
  extend MarshalByRefObject or ContextBoundObject.
• DynamicProxy can be used to generate proxies on
  the fly for one or more interfaces or even
  concrete classes (but only virtual methods will
  be intercepted).
• To achieve good performance, DynamicProxy
  generates a Multicast delegate for each method
  that is going to be intercepted. Thus no
  invocation happens using reflection and delegates
  have an extremely good performance compared to
  reflection based invocations.

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AspectSharp

• Aspect-oriented programming (AOP) is a new
  programming paradigm that allows modular
  implementation of crosscutting concerns.
• Aspect is an AOP (Aspect Oriented Programming)
  framework for the CLI (.Net and Mono). It relies
  on DynamicProxy and offers a built-in language to
  declare and configure aspects, and is compliant
  with AopAlliance.
• Aspect promotes -
• Separation of concerns
• Code reuse
• Decomposition

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Related Links

• Castle Project
• http//www.castleproject.org/index.php/Main_Page
• Introducing Castle 1
• http//codeproject.com/csharp/IntroducingCastle.as
  p
• Introducing Castle 2
• http//www.codeproject.com/csharp/IntroducingCastl
  eII.asp
• I want my AOP (three part series)
• http//www.javaworld.com/javaworld/jw-01-2002/jw-0
  118-aspect.html