I’m giving two presentations in the morning. The first presentation has been on tour quite a bit in 2008 starting with Tech Ed 2008 and then on an INETA User Group tour in the summer. The second presentation is brand new and based on my upcoming book and lessons learned on real projects I’m directing. If you are in the area, make sure to register on the site and come on out.
TDD, DI, and SoC with ASP.NET MVC Description: Spelled out, it is test-driven development, dependency injection, and separation of concerns with Active Server Pages .Net Model View Controller. This talk will dive into how to design a presentation layer using ASP.NET MVC. In today’s industry, TDD, DI, and SoC are proven concepts that lead to more maintainable applications. Along with demonstrating how to use these techniques with ASP.NET MVC, we will discuss just what concerns should be separated. This talk provides a unique perspective on separation of concerns and uses TDD and DI to make it happen. MvcContrib is used in all the demos.
ASP.NET MVC in Action Microsoft is releasing a new version of ASP.NET that uses a model-view-controller pattern for handling an http request. This session will not cover the basics of the ASP.NET MVC Framework. Instead, this session serves the advanced developer looking to get past basic samples and dive into working with this new version of ASP.NET to create complex business applications. The material will cover as much design as anything else, and the speaker will share real-world experiences using ASP.NET MVC in enterprise applications. Get a good night’s sleep before coming because the pace will be fast and the coverage deep.
Views have long been abused in the Microsoft web application space. In Classic ASP, and in IDC/HTX before that, the view was the primary programming tool for the Microsoft-centric developer. Using the server page pattern, developers used IDC and ASP pages as transaction scripts to perform a single operation and render a screen. Each page has logic, behavior and UI. ASP.NET 1.0 sought to separate logic from the UI rendering in an effort to make applications easier to maintain and extend. Having logic intermixed with screen rendering had proved to be an unworkable solution for many teams. While it certainly was possible for teams to separate the concerns in their applications, Microsoft had provided no guidance on how to do so, and most samples and demo applications encouraged the intermingling of concerns. ASP.NET set the foundation for how a Windows web server would handle web requests. The framework has proved to be highly scalable and robust. One specific part of the framework that developers are most familiar with, WebForms, has underperformed expectations. The code-behind idea did, in fact, separate logic from UI rendering, but in practice, and coupled with guidance available in the industry, the logic ended up merely separated in a separate file instead of abstracted into new concepts. WebForms continued the server page pattern started in IDC and carried through Classic ASP. This server page pattern is being dropped with the new version of ASP.NET, ASP.NET MVC.
ASP.NET MVC views and WebForms views can coexist side-by-side, so it is possible to do a phased port from WebForms to ASP.NET MVC. WebForms, however, serve a much bigger purpose in the application than MVC views. For instance, by the time your code executes in a Web Form Page_Load, the framework has already:
Selected the Web Form to execute
Constructed the Web Form and all its design-time controls
Processed any ViewState received.
With a Web Form, your code runs as the page is executing. There are plenty of ways to get into the pipeline before the page starts executing, but it is not obvious or easy. A Web Form is built upon the concept of a Control, which is the building block of the page. Controls can have child controls, and System.Web.UI.Page derives from System.Web.UI.Control. A control’s purpose is to be responsible for the behavior and rendering of what will ultimately become an html element on the web page. During the heyday of browser wars and incompatibility, controls were able to render different markup based on the browser receiving the page. This was a very useful feature in 2002 and 2003. With Internet Explorer 7 and FireFox 2+ now responsible for more than half of the browser markup, most web users employ a more standards-compliant web browser than was the case in 2002; therefore the risk of rendering the same markup to all users has been mitigated by the market.
ASP.NET MVC Views take back control of html markup. While it is possible to use existing controls for their rendering capabilities, the guidance with MVC views is to lay out the html by hand and use server delimiters to make parts of the view dynamic. MVC views leverage the Web Forms rendering engine but jettison the post-back logic, viewstate, and control hierarchy. An MVC view renders top to bottom and then goes away. An MVC view has much less responsibility than a Web Form. The view accepts objects in its ViewData dictionary and transforms those objects into a response suitable for the web. That is it. No decision logic, no permissions, no database access, no web service calls, just rendering. MVC views can still use a code-behind file, but they are not necessary. This ability comes from the fact that System.Web.Mvc.ViewPage derives from System.Web.UI.Page. If you are porting an application from Web Forms to ASP.NET MVC, you will find yourself moving much of your code-behind logic into a controller. You will also probably find that much logic does not even belong in a controller. You will most certainly need to develop additional classes to absorb logic that has inappropriately lived in a Web Form code-behind file.
This advanced agile curriculum will cover everything involved in developing software in .NET, from setting up a new project and defining the architecture to implementing functionality in a loosely-coupled and testable manner. We will immerse ourselves in domain-driven design, test-driven development, design patterns, object-relational mapping, inversion of control (IoC), pair programming, automated builds, and continuous integration (CI). Students will discover which practices cause projects to fail and which practices help projects succeed. The course will include a strong focus on solid principles and values that can be applied to any .NET project. With a solid understanding of Agile values and object-oriented programming, students will emerge from the training with a refocused view on software development and the tools to immediately bring value back to their companies. All developers will take back working code developed during the course using the techniques and practices taught.
This course moves very quickly and is not for the faint of heart. Below are some of the topics that are covered:
“Man! we actually covered a lot! Jeffrey did a great job of making it seem like not much, but when I got back and started telling my boss about it, there were just TONS of things to talk about. We talked about Team Estimation and Design, NHibernate Mappings, Test-Driven Development, Domain Driven Design, Automated Builds and on and on and on. I have absolutely no idea how we managed to cram all that stuff in three days, but we did.”
“While a lot of software development training is often presented very academically, Headspring’s was very hands-on and really pushed everyone to pick up the processes and tools very quickly, just as you would in the real world.”
“This was an excellent training event, and I plan to steal be inspired to use some of his methodologies at Interface Technical Training.”
Brad Mellen-Crandell Rapidparts Inc.
“This was the best technical training course I’ve been to, period. No fluff here. The course was packed with information and best practices that I could start implementing immediately when I got back to work on Monday.”
Ken Jackson
“Jeff is an excellent teacher and practitioner of Agile principles and methods. His integration of open source tools to boost productivity will surely help me be more successful and confident in my daily working regimen.”
Monday, October 13, 2008 at 08:00 AM – Friday, October 17, 2008 at 05:00 PM (CT)
Austin, TX
Introduction Designing large-scale distributed systems is hard. New technologies make it easier to comply with today’s communications and security standards, but don’t auto-magically give you a robust and scalable system. Join Udi for a course packed with the wisdom of companies like SUN, Amazon, and EBay.
Tried-and-true theories and fallacies will be shown, keeping you from making those same costly mistakes today. Communications patterns like publish/subscribe and correlated one-way request/response will be used in conjunction with advanced object-oriented state management practices for long-running workflows. If you enjoy deep architectural discussion, if you are in charge of building a large-scale distributed system, if you want to know more about how the big guys run their systems, this is for you.
About Udi Udi Dahan is The Software Simplist, recognized by Microsoft Corporation with the coveted Most Valuable Professional award for Solutions Architecture now 4 years running. Udi is a Connected Technologies Advisor working with Microsoft on WCF, WF, and Oslo. He also serves as a member of the Patterns & Practices Advisory Board for the CAB and Prism. He provides clients all over the world with training, mentoring and high-end architecture consulting services, specializing in Service-Oriented, scalable and secure .NET architecture design.
Udi is a member of the European Speakers Bureau of the International .NET Association, an author and trainer for the International Association of Software Architects and a founding member of its Architect Training Committee. He is also a Dr. Dobb’s sponsored expert on Web Services, SOA, & XML.
Presenting at international conferences like TechEd USA, SD Best Practices, DevTeach Canada, Prio Germany, Oredev Sweden, TechEd Barcelona, QCon London, and TechEd Israel – Udi covers in-depth mission-critical topics like durable services, persistent domain models, and multi-threaded occasionally connected clients.
Audience This workshop is targeted at team leads, application and solutions architects, as well as technologists who are involved in making decisions about the overall system design of software products and projects.
Course Topics
Module 1: Distributed Systems Theory Decades of distributed systems development have taught us many lessons. In this module we’ll cover many historical mistakes as well as proven best practices for scalable and robust design. Topics include: • 8 fallacies of distributed systems • Transactions
Module 2: Coupling: Platform, Temporal, & Spatial Loose coupling has become the watchword of complex systems development, yet few understand its multiple dimensions. In the module we’ll be covering the three different dimensions of coupling as well as patterns for dealing with them. • Platform Coupling – XML/SOAP • Temporal Coupling – Synchronous/Asynchronous • Spatial Coupling – Endpoints/Topics
Module 3: Asynchronous Messaging Patterns Although scalability is achieved through the use of asynchronous message passing, more advanced message exchange patterns are required to handle today’s complex integration scenarios. This module will cover the most commonly used patterns: • One way • Correlated Request/Response • Publish/Subscribe
Module 4: Bus & Broker Architectural Styles Enterprise Service Buses are all the rage these days. In this module we’ll be covering what’s the difference between the Bus architectural style, and the more well-known Broker, found commonly in many EAI projects. Topics will include: • Architectural advantages and disadvantages • Technological advantages and disadvantages
Module 5: SOA Building Blocks One of the goals of SOA is to develop systems which are more closely aligned with Business. In this module we’ll be covering an analysis methodology from moving from the business domain to executable systems that comply with all the principles of loose-coupling. • Business Services • Business Components • Autonomous components & Queues
Module 6: Scalability and Flexibility In order to enable agility, services must be able to scale up, out, and down quickly. In this module we’ll see how autonomous components can be configured including transactional and durable aspects of message handling. • Configuring autonomous components • Scaling up and out
Module 7: Long running processes The distributed communications patterns wouldn’t be complete without a discussion on orchestration. In this module we’ll see how to manage the state of long-running distributed communication flows as well as: • Encapsulating process logic • Advantages & disadvantages of orchestration
Module 8: Service / Autonomous Component Solutions As developers go to implement autonomous components, guidance is required as to which concepts need to implemented in which project, what dependencies are there between projects, and how to bridge the worlds of messaging, business logic, and reporting. Topics include: • Messages + Handlers • Databases
Module 9: Service Layer – Domain Model Interaction Logic-rich services require the use of advanced techniques for logic componentization. The Domain Model Pattern enforces a high level of Separation of Concerns, yet it must eventually be connected with Service Layer code that supports many concurrent users. In this module, the topics covered will include: • Domain Model introduction • Testing Domain Models • Optimistic, Pessimistic, and Realistic Concurrency Models
Module 10: Creating High-Performance Domain Models The strong separation between the Domain Model and the database which stores and retrieves its data may enable a high level of testability, yet often causes performance problems. In this module, we’ll see the various aspects impacting the performance of persistence: • Transactions and Isolation Levels • Lazy Loading, Eager Fetching • Databases Tips & Tricks
Module 11: Web Services and User Interfaces The ease of interacting with users over the web drives the need for service to UI interactions. Also, many integrations require exposing synchronous web services to customers. In this module, we’ll see what is required in both cases: • ASP.NET 2.0 Asynchronous Tasks • Rich Internet Applications and Services • Web Services for integration
Module 12: Smart Client / Service Interaction The publish/subscribe semantics with which services communicate require smart clients to perform a great deal of background work. Also, certain service contracts lead to more performant clients. In this module, we’ll cover the first part of these interactions: • Multi-threaded client challenges • Client-friendly Service Contracts • Service Agents and Client Repositories
Module 13: Notifications & Smart Clients After Message Handlers in the Service Layer create or update the relevant Model objects in the client Repository, Supervising Controllers are in charge of getting Views to show the updated data. In this module, we’ll describe the parts and interactions of these flows: • Client-side Model Objects • Supervising Controllers • Views and their Interfaces
Module 14: Commands & Smart Clients Capturing user intent and synchronization between views are at the core of smart clients. After describing solutions that use Events on the View Interfaces, the Command Pattern will be introduced to further decrease coupling between Supervising Controllers. In this module, we’ll describe the parts and interactions of these flows: • View Interfaces, and how Entity Cloning affects them • Supervising Controllers and clone reconciliation • Commands, and Event-Based programming
I’m still hoping that SubControllers make it into the MVC Framework release, but my company is doing several client projects right now using the MVC Framework. These projects are enterprise applications, not smaller websites, so subcontrollers are absolutely necessary to handle the complex logic and permissions. I’ve create an implementation of subcontrollers and added it to MvcContrib. It is pulling its weight on one client project, so I’m happy with it. It can be made better, and I’m hoping the team can take my first draft and incorporate it into the product.
Matt Hinze has recently done a very nice write-up on his experience using MvcContrib SubControllers. I also recommend subscribing to his blog.
Feel free to pull down the source and let me know what you think. Even better, if you find an idea for improvement, please submit a patch. I have leveraged the IModelBinder so that subcontrollers can be passed directly into action methods, and you can hook your IoC container up so that it creates the subcontrollers and the dependencies. Decomposing complex screens infinitely increases maintainability, so this is why I consider subcontrollers a critical feature. Even if this doesn’t make it into the product, the team has done a good job making the framework extensible, so I was able to implement subcontrollers in less than 150 lines of code. I welcome your thoughts and opinions.
You can pull down the source for MvcContrib by pointing your TortoiseSVN client to http://mvccontrib.googlecode.com/svn/trunk/ Note that this is a SVN URL, not a web page URL
Casey’s Bar & Grill http://www.bigcaseys.com/
613 S Grand Ave, Los Angeles, CA 90017
Ph: (213) 629-2353
Cover charge is 1 business card. This will get you in the door and register you for the grand prize drawings.
The Global.asax.cs file contains some routes that are provided with the MVC Web Application project. Before continuing, we must define what a route is. A route in the ASP.NET MVC Framework is the complete definition for how to handle a web request. With Web Forms, we have little control over this without resorting to url rewriting. With Web Forms, the url of the web request is tightly coupled to the page handling the request. If the page was named Foo.aspx in a folder named Samples, then the url was sure to be http://mvccontrib.org/Samples/Foo.aspx. Many teams have resorted to url rewriting to wrangle some control over the urls and how to satisfy each request. With the ASP.NET MVC Framework, routes are first class citizens in the web application. We start with defining how we want our urls structured. The project template gives us a few routes to start, shown in Listing 1.1.
Listing 1.1 Default routes for a new project. These are added by the project template.
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
namespace GettingStarted
{
publicclass GlobalApplication : HttpApplication
{
publicstaticvoid RegisterRoutes(RouteCollection routes)
{
routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
routes.MapRoute(
"Default", // Route name"{controller}/{action}/{id}", // URL with parametersnew {controller = "Home", action = "Index", id = ""}
);
// Parameter defaults
}
protectedvoid Application_Start()
{
RegisterRoutes(RouteTable.Routes);
}
}
}
Routes need to be defined as one of the first things when the web application starts up, so the project template adds the routes to the Application_Start method in the Global.asax.cs file. Later in the book, you’ll see that we don’t leave the routes in this location except for the most trivial of web applications.
Note
We will follow long-standing best practices of Separation of Concerns and the Single Responsibility Principle , or SRP, by moving the routes to a dedication location separated by an interface. We’ll go more into these principles later, but, in short, the responsibility (or concern) of the Application_Start method is to kick off operations that must happen at the beginning of the application’s life. The responsibility is not to perform every bit of work that must happen on start. Any operations that must happen on application start should reside in separate classes and merely be called in the appropriate order in the Application_Start method.
Note that the url portion of the route is simply a matching mechanism for the request. If the url matches a particular route, then we specify what controller should handle the request and what action method should execute. You can create as many routes as you like, but one route is provided for you. This route has the template, {controller}/{action}/{id}.
Note
This is a very generic route and could be used for many, many different web requests. Tokens are denoted by the inclusion of {braces}, and the word enclosed in braces matches with a value the MVC Framework understands. The most common that we’ll be interested in are controller and action. This is the route we will be using for the rest of the chapter, so we will be content with a url in the form of http://mvccontrib.org/controllername/actionname. The basic RouteHandler is an instance of IRouteHandler and we’ll use MvcRouteHandler most of the time. We have complete control and could provide our own implementation of IRouteHandler if we wished, but we’ll save that for a later chapter.
Before we spin up our first controller, let’s examine what is different about the web.config file in an MVC Web Application project. The differences are easy to spot. Just look for “routing” or “mvc”. One difference we see is that a new IHttpModule is registerd in the config file. Here, we see the UrlRoutingModule in listing 1.2
Listing 1.2 Unique addition to the web.config file. The rest of the web.config file is standard for .Net 3.5.
The UrlRoutingModule evaluates a request and sees if it matches a route that is stored in the RouteTable. If the route matches, it overrides the default handler (IHttpHandler) for the request so that the MVC Framework handles the request. We are going to examine our first controller as a means to handle a route for the url /home. In the next section you will see how all the pieces of the starter project fit together.
