Building in n-tier in Visual C#

Encoding Code39 in Visual C# Building in n-tier

Going the opposite direction from inline code, I have what used to be called n-tier code, but now it s called a hundred different things At the essence here, I am talking about purposefully dividing the code of the application up into DLLs, instead of just having Visual Studio do it for you

To show what I mean in pictures, Figure 2-8 shows a normal code-behind style ASPNET application Now, say you put all the data access code code that talks to the database in one class project Then you put all the business logic math and validation and stuff in another class project

All the code in the code-behind layer, then, would be stuff that makes the markup work, right Yup That s the idea Layering your application like this makes debugging easier, separates concerns even more, and provides for code reuse If you have a cellphone application that uses the same data model, then you can use the same database code if you break it out Implementing n-tier is simple Just make a class project for every logical division in your code Something so simple can sometimes be demanding, however Determining where to put what and how to hook everything together is non-trivial but also beyond the scope of this book recommend getting some of the Wrox Professional ASPNET titles to learn more about Web application architecture

ASPNET MVC takes the idea of n-tier a step further by formalizing it The tough decisions I mention related to deciding where everything goes are largely made for you in ASPNET MVC MVC stands for Model View Controller In a nutshell, the idea is that your markup goes in the View, your business logic goes in the Controller, and your database connection code goes in the Model Sounds like n-tier to you, too, huh I understand The differences are mostly theoretical

The big benefit to MVC over other kinds of Web forms apps is that the user interface code is much more testable with automated tests In fact, when you start an ASPNET MVC project, it asks you to create a test project along with it Another difference from n-tier is some formalization to the implementation of MVC It is a project type, and rather than having to figure out how things hook up, MVC does some of the work for you MVC is a big topic that I just can t cover here in any detail If you have a large project for which you need to divide up the work among developers with varying skill sets, it s cool Read more in Professional ASPNET by Wrox Press

Showing stuff to the user Getting some input from the user Binding Styling with the best Making sure the site is accessible Constructing user controls Adding custom controls

SPNET is a rendering engine It takes preset batches of functionality and renders it into HTML For instance, ASPNET can take a database table and a little bit of layout information and make a nice, dynamic HTML table Rendering engines are a good idea in the W world With a bunch of different implementations and versions, your rendering engine can produce different user markup out of the same effective code base ASPNET does this well You can tell it to make mobile-device markup and text-only markup and rich Internet Explorer markup from the same ASPNET file, and it will do an okay job This is possible because of Web controls Web controls are controls that ASPNET renders into client-side markup, like HTML, CSS, and JavaScript Well-programmed controls protect the developer from the implementation details but can still do what is needed to be done when the time comes Web controls aren t anything special Basically, they show a pretty text box in the designer pane of Visual Studio, and then emit text an <input> tag when called upon to do so ASPNET has a lot of included controls, many other controls are available from third-party providers, and you can even build your own and base them on existing controls It s a good system