In a three-layered architecture, where is the DAO pattern located? Is it in the business logic layer or in the data layer?
I'm not sure that thinking in terms of layering is useful anymore.
We used to have 2-tier client-server, with all the logic in the client and a database running on a server.
We evolved to 3-tier, usually associated with MVC model-view-controller. There wasn't a mention of data access objects in the original Smalltalk MVC pattern.
Now I think view and controller generally go together, splitting rendering of the user interface between client and server. Controllers have business logic and interact with many web and data access services. Data access objects would be used by controllers to deal with data sources. Call that whatever layer you wish.
I don't think of microservices as a layer. Perhaps the usefulness of the concept has diminished.
I am new in MVC and little confuse and want to ask about differences and purposes of both.
MVC model and Business Logic layer (BLL) in tier Architecture.
What is the purpose and need to use BLL? some say they exchange the data between Presentation layer and data access layer. except these elaborate the BLL purpose.
So, we create properties in both MVC Model and BLL. So mention the proper difference and similarities if it has with the relevant code or example
Thanks
To me the M in MVC is about the view model used by the view. Each view has its dedicated view model, that contains all information needed by the view.
These view models are built in the controllers based on the DTO's that you receive from your back-end.
The BLL you are talking about is more the business layer on the back-end, which you don't know in your front-end logic. Often people use a domain driven approach or this layer.
I currently have a web application that is based upon a 3 Tier architecture. I wish to change my Presentation layer from using Web Forms to MVC4.
Now I have done some research and from what I read I understood that the View represents the .aspx of a Web Form. The Controller represents the Code Behind (.cs) of a Web Form.
The problem that I have is that I do not see any use for the Model. This is because I can directly call methods from the Business Logic Layer directly from the Controller making the purpose of the Model useless.
Is there something that I am misunderstanding? If so what are you views on implementing an MVC design patter for the presentation layer in a 3 layer architecture?
In a simple application the model in MVC can simply be the DTOs from the Application or Business Layer. In this case you're right, you probably don't need a separate model in the UI.
Is to possible to have a layout for web-based architecture based on MVC where SOA is the architectural style. Or to rephrase, can services be part of the M,V, C of MVC.If so, what kinds of services can be included in each of them. Also, can you give me a real world example?
In a SOA application you are typically not including the front end (presentation layer). You are consuming those services in your MVC application, or better yet in a separate "model" project that the MVC application uses.
Data Access -> Business Logic -> Services -> Models -> MVC
The point is to use the services to create an abstraction around the base of your application to allow for multiple clients to consume those services.
I tend to term the Model as represented in the client/presentation layer as the ViewModel, it is simply the presentation layers view of the model. Not the actual Domain model.This is needed in a SOA as the context of the consumer of the Model changes often
In SOA`s we try to get to a canonical schema for the contract, as it is quite likely that not all clients now and in the future will require the exact same view of the model.
Thus be it a web client, service client or a desktop client, if you think of the Model in MVC as the ViewModel, this allows you to abstract presentation layer things away from Service layer things, and you get closer to a canonical schema.
So an example View >> Controller >> ViewModel(Model) >> Data Contract >> Service
Examples of how to build a service stack like this can be found here:
SOA Design Pattern
The decision of whether to go with a REST architecture or a full WS-* SOAP is a separate concern and should not affect your choice of MVC as a presentation pattern.
There may of course be other constraints that preclude the use of one or the other.
Choosing a presentation pattern for a new or enterprise web development on the Microsoft platform is a daunting task, in my opinion there are only three; View Model, Model-View-Presenter (MVP) or ASP.NET MVC (a Model2 derivative).
You can read the full article here ASP.NET MVC Patterns
This depends on what you mean by SOA. If you are referring to WS-* standards, I would not recommend MVC, as you will need to write a lot of plumbing to get it to work.
If you are looking for something like a REST service, then the MVC pattern actually works quite well. The request is the HTTP location of the resource, which gets passed to the controller, which loads the data via the model, and then passes it to the view which returns it in whatever form is needed (JSON, XML, Binary, etc). Or, you can often return the result directly, depending on what framework you use.
Erick
I know that an MVC framework allows you to separate business logic, data base access and presentation, but why do we need a framework to do this.
Can't we just keep our classes separated, perhaps using different packages/folders for the model, view and controller classes?
In my opinion the thing you are talking about is the MVC pattern and not a specific framework. Of course you can go and keep all your classes within one project and still use the MVC pattern, as you have all your UI code in the views, the logic in the controllers, ...
A MVC framework on the other hand makes it easier for you to use this pattern. It may provide some base classes for controllers and a mechanism for the communication between view and controller.
I don't know if you are familiar with ASP.NET MVC. The framework itself is very small, but it helps you developing an application with the MVC pattern, as you don't have do think about the previously decribed areas...
Hope this helps
An MVC framework is a framework written to split up the the business logic, database access and presentation.
This is very useful in most web applications, and now lately into software/desktop applications.
This is due to the fact that following the MVC model, your code will be much clearer, cleaner and you keep your application DRY (Do not Repeat Yourself).
You can write your own classes and separate them into Model, View and Control. But again, you will need a framework to help you in accomplishing certain tasks. Like a List control in ASP.NET, or PHP framework being able to help you translate text between languages and so on. (Oh why reinvent the wheel?!)
MVC and framework is a different thing. MVC is just an architectural pattern, which can be applied with any project, with or without framework.
So you don't need a framework to do this. You can separate them by yourself. :)
MVC stands for “MODEL” “VIEW” “CONTROLLER”. ASP.NET MVC is an architecture to develop ASP.NET web applications in a different manner than the traditional ASP.NET web development. Web applications developed with ASP.NET MVC are even more SEO (Search Engine) friendly.
Developing ASP.NET MVC application requires Microsoft .NET Framework 3.5 or higher.
Model:
MVC model is basically a C# or VB.NET class.
A model is accessible by both controller and view.
A model can be used to
pass data from Controller to view.
A view can use model to display
data in page.
View:
View is an ASPX page without having a code behind file.
All page specific HTML generation and formatting can be done inside view.
One can use Inline code (server tags ) to develop dynamic pages.
A request to view (ASPX page) can be made only from a controller’s action method
Controller:
Controller is basically a C# or VB.NET class which inherits system.mvc.controller.
Controller is a heart of the entire MVC architecture.
Inside Controller’s class action methods can be implemented which are responsible for responding to browser OR calling views.
Controller can access and use model class to pass data to views
Controller uses ViewData to pass any data to view.
MVC is a code organization architecture style to organize your code-logic in a meaningful way for web applications. As a programmer I have almost puked when I have inherited other people's code when their code logic is all over the place and following their web application code turns into following a rabbit down the gutter hole. Why MVC? hmm.. well why should I use a filing cabinet or folders to organize my plethora of paper and not just have my papers stashed in a large pile and have others figure how they connect to each other. It increases code readability. With MVC it becomes very easy to follow code logic since you are following standard structure for a web application. Business logic is separated out from UI. Easier to delegate work decouple work on a project.
You can of course approach it yourself by segregating your classes. A framework supplies common scaffolding that you wouldn't have to build yourself. But it will also impose some structure on your code. You'll have to evaluate whether the framework helps more than it hurts.
You are correct, there are strategies that you can implement to help with separation of concerns without using MVC.
Microsoft's ASP.NET MVC framework is one strategy that can be employed, and that is what I think you are asking about.
This MVC framework makes such separation of concerns easy.
The other major advantage of MVC is testability - (depends on whether you believe in unit testing - I do).
The MVC framework ensures that all orchestration logic is on your controllers and through the FormControls collection allows full unit testing of all aspects of your application except for how it is presented.
As the MS MVC framework encourages adherence to common rules and structure of the application which should lead to greater maintainability.
The major downside of MVC is the code-in-front code weaving required for presentation, but this can be easily overcome.
Perhaps this is just a linguistic thing. I've seen "frameworks" referring to themselves as a DSL -- Domain Specific Language.
And you don't need a framework But here's something to consider: You already know for a web app you're going to want to do a few common things... route URLs, render pages, etc. Why re-write it all? For other problem domains you'll have generic things to do as well.
Hai Friends There are somemany types of architecture frame work has been there,firstly i know 2tier and 3 tier frame work ,the 3 tier and mvc ,entity framework are same but in different name's,so study a good background in any one architecture there fore if you went to any multinational companies ,you can easly score/highlight to your carrer.
Model View Controller or MVC as it is popularly called, is a software design
pattern for developing web applications. A Model View Controller pattern is made
up of the following three parts:
**Model** - The lowest level of the pattern which is responsible for maintaining data.
**View** - This is responsible for displaying all or a portion of the data to the user.
**Controller** - Software Code that controls the interactions between the Model and View