Model-View-Presenter
In MVP, the Presenter contains the UI business logic for the View. All invocations from the View delegate directly to the Presenter. The Presenter is also decoupled directly from the View and talks to it through an interface. This is to allow mocking of the View in a unit test. One common attribute of MVP is that there has to be a lot of two-way dispatching. For example, when someone clicks the "Save" button, the event handler delegates to the Presenter's "OnSave" method. Once the save is completed, the Presenter will then call back the View through its interface so that the View can display that the save has completed.
MVP tends to be a very natural pattern for achieving separated presentation in WebForms. The reason is that the View is always created first by the ASP.NET runtime. You can find out more about both variants.
Two primary variations
Passive View: The View is as dumb as possible and contains almost zero logic. A Presenter is a middle man that talks to the View and the Model. The View and Model are completely shielded from one another. The Model may raise events, but the Presenter subscribes to them for updating the View. In Passive View there is no direct data binding, instead, the View exposes setter properties that the Presenter uses to set the data. All state is managed in the Presenter and not the View.
- Pro: maximum testability surface; clean separation of the View and Model
- Con: more work (for example all the setter properties) as you are doing all the data binding yourself.
Supervising Controller: The Presenter handles user gestures. The View binds to the Model directly through data binding. In this case, it's the Presenter's job to pass off the Model to the View so that it can bind to it. The Presenter will also contain logic for gestures like pressing a button, navigation, etc.
- Pro: by leveraging data binding the amount of code is reduced.
- Con: there's a less testable surface (because of data binding), and there's less encapsulation in the View since it talks directly to the Model.
Model-View-Controller
In the MVC, the Controller is responsible for determining which View to display in response to any action including when the application loads. This differs from MVP where actions route through the View to the Presenter. In MVC, every action in the View correlates with a call to a Controller along with an action. In the web, each action involves a call to a URL on the other side of which there is a Controller who responds. Once that Controller has completed its processing, it will return the correct View. The sequence continues in that manner throughout the life of the application:
Action in the View
-> Call to Controller
-> Controller Logic
-> Controller returns the View.
One other big difference about MVC is that the View does not directly bind to the Model. The view simply renders and is completely stateless. In implementations of MVC, the View usually will not have any logic in the code behind. This is contrary to MVP where it is absolutely necessary because, if the View does not delegate to the Presenter, it will never get called.
Presentation Model
One other pattern to look at is the Presentation Model pattern. In this pattern, there is no Presenter. Instead, the View binds directly to a Presentation Model. The Presentation Model is a Model crafted specifically for the View. This means this Model can expose properties that one would never put on a domain model as it would be a violation of separation-of-concerns. In this case, the Presentation Model binds to the domain model and may subscribe to events coming from that Model. The View then subscribes to events coming from the Presentation Model and updates itself accordingly. The Presentation Model can expose commands which the view uses for invoking actions. The advantage of this approach is that you can essentially remove the code-behind altogether as the PM completely encapsulates all of the behavior for the view. This pattern is a very strong candidate for use in WPF applications and is also called Model-View-ViewModel.
There is a MSDN article about the Presentation Model and a section in the Composite Application Guidance for WPF (former Prism) about Separated Presentation Patterns
On my quest for the truth I discovered that there are actually very few "acceptable" reasons to use a Singleton.
One reason that tends to come up over and over again on the internets is that of a "logging" class (which you mentioned). In this case, a Singleton can be used instead of a single instance of a class because a logging class usually needs to be used over and over again ad nauseam by every class in a project. If every class uses this logging class, dependency injection becomes cumbersome.
Logging is a specific example of an "acceptable" Singleton because it doesn't affect the execution of your code. Disable logging, code execution remains the same. Enable it, same same. Misko puts it in the following way in Root Cause of Singletons, "The information here flows one way: From your application into the logger. Even though loggers are global state, since no information flows from loggers into your application, loggers are acceptable."
I'm sure there are other valid reasons as well. Alex Miller, in "Patterns I Hate", talks of service locators and client side UI's also being possibly "acceptable" choices.
Read more at Singleton I love you, but you're bringing me down.
Best Answer
Flexibility without complexity... nice program.
Maybe you're a genius and you will make something that feet your needs. But I think the biggest problem you will face is security and robustness. So really, take other advices on this page and have a look at wordpress, drupal, joomla and ezpublish. A lot of security stuff is already done. And not only security...
So, study some of these tools, track their flaws, check their security policy. Study how they handle caching, sessions, bootstrap, absolute & relative url managment, documents (images, videos, etc), ajax, authentification, identification, acl, user interfaces, rich-text editing, migrations, templating, page composition, content filtering (I try to remove the things you won't need, plugins, database abstraction, fine caching, css and js minification, all the extra-complex stuff not needed for a single instance simple CMS). Soon you'll have a 'picture' of the stuff they've done.
By doing this work, you'll certainly notice some big differences, and mistakes. You'll start going on irc and flaming developpers, telling them that others have done better choices. You'll start forgetting to shave. You'll maybe do some contributions. Some will be accepted, others won't. Old core devs doesn't like when someone explain why they made mistakes (and they make mistakes).
Now, comes the day you have a beard. Some of your contributions will start looking like forks. You will have ennemies, and friends, or followers. And you will start feeling the force.
And you will go on irc and tell god that the world is ugly and that you'll make the first CMS which will be flexible without being complex. And people will cry. And birds will run in circles. And you will be able to explain what are the design pattern of a CMS.
Seriously, There's still a place for a good CMS with disruptive innovation, the fork history has started long time ago with phpNuke (as far as I can remember). But some of the actual products are really fine for most tasks.