Architecture :: The Respository Pattern In A Layered Web Environment?
Oct 27, 2010
I have been looking at the Repository Pattern. While trolling around the net I have come across many implementations and examples. Many of these examples have code like:
Since the Repository basically serves as the Data Access Layer, doesn't this violate the principles of a layered approach by having a UI component accessing the data access layer? If so, my assumption is that I would need to wrap the call CustomerRepository.GetAll() in some business object like:
ObjectDataSource1.Datasource = CustomerManager.GetAll();
where CustomerManager calls CustomerRepository.GetAll();.
If this is correct, what benefit am I getting by wrapping a business class around the Repository? It seems like I am adding an extra layer for the sole purpose of avoiding calling the DataAccessLayer/Repository directly from the UI?
Is it okay for the UI to have access to my Data Access layer in order to read data from the database?
I am a asp.net developer and don't know much about patterns and architecture.In my web applications I use 4 layers.Web site project (having web forms + code behind cs files, user controls + code behind cs files, master pages + code behind cs files)
CustomTypesLayer a class library (having custom types, enumerations, DTOs, constructers, get, set and validations)
BusinessLogicLayer a class library (having all business logic, rules and all calls to DAL functions)
DataAccessLayer a class library( having just classes communicating to database.)
-My user interface just calls BusinessLogicLayer. BusinessLogicLayer do proecessign in it self and for data it calls DataAccessLayer funtions.
-Web forms do not calls directly DAL.
-CustomTypesLayer is shared by all layers.
I though it may be MVC or MVP but pages have there code behind files as well which are confusing me.
guide in typical 4 layered architecture (having User Interface, Custom Types, Business Logic, Data Access Layer) do we follow some design pattern ? I am not clear what pattern it is or what pattern it should be called.
Does data binding fit in a 3 layered architecture? Is dropping a grid-view on a web form and binding it to a LinkDataSource or SQLDataSource considered bad? The way I see it, that's the Presentation Layer talking to the Data Access Layer. I once heard a "professional developer" say never ever do this, so what's the alternative if you shouldn't?
I'm thinking of using 3 layered architecture in my web site.Kind of classic layers - Presentation, BL, DAL and BO - business objects, just like in this great article http://imar.spaanjaars.com/QuickDocId.aspx?quickdoc=416I will have 4 projects according to levels.I'm goung to store data in xml files and my question is where should those files be located? In App_Data folder of web site? Then how DAL will know path where to find files to parse?
where to create the BLL and DAL and all classes in it can we place them in the App_code folder as it ll convert them into DLL Files or do we have to create a new class library project for each...
I am a newbie to asp.net and work in a firm where the projects are quite small.
I was told by my manager that in a few weeks or so we would be getting a bigger project and I need to be well versed with Design Patterns and N tier arcihtecture.
I would really appreciate if someone could provide me some links and also drop me a few sentences on how this things are useful?
I wanted to know which all design pattern have you used in your application. Just wanted to see a general idea of most commonly used, popular design patterns. I was going through this site"
http://www.dofactory.com/Patterns/Patterns.aspx
and it has tons of design patters, I have heard about singleton and factory but not others.
So guyz which all popular efficient patterns are there and how would you determine which one suits your app. Can we make a app without a design pattern.
And lastly which one are the most simplest ones out there which are easier to implement.
How can we use ObjectDatasource with MVP pattern in ASP.NET application?
In 3-tier architecture there is no Data Access layer,.in place of DAL, I want to consume Web Services and Request and Response is in the form of Custom objects i.e. BusinessRequest and BusinessResponse class type.
Is it possible to merge all these in one solution, MVP, 3-tier web application, No DAL, Only consuming Web Service , BAL, ObjectDataSource, GridView?
I just started working on one of the application, bascially its some maintanence work. I see from the application that Facade pattern has been utilized as I see Class Library projects named as Business Facade, Data Facade.
Though I am not redesigning this, but just wanted to know what this pattern is, a simple explanation, use, real world example should be good enough. The application is basically a banking app. I know its diff but if anyone can give me some hints/points as in why the designer chose this pattern (banking app).
I am working on singleton desing patterns and want some real world example of design patterns.Can you please give me an example how you have used singleton pattern in you project. I would appreciate if you can provide code.
suggest me a good design pattern for implmenting the following? I have an object say myObject. This myObject is created using few inputs from the UI. After the creation of myObject. This object will be passed to few methods.. like method1(myObject);
method2(myObject);... method5(myObject);etc. Each methods will prepare the input for successive methods call. For example method1(myObject) will set the values necessary for the operation of method2.Then method2(myObject) will set up the values necessary for the operation of method3 and so on..Same object is used as the argument for every method calls.Which design pattern can be implemented?
This is possibly the worst kind of religious debate -- a religious debate with practical consequences. But it's one that needs to be had, and I can't seem to fit it in my tiny head. Here are the pros and cons of the pattern as I know them:
Pros:
-Encourages DRY (don't repeat yourself) design in that identical queries are written only once per set of query conditions -Facilitates unit testing by allowing itself to be abstracted into an interface -Creates an opportunity for business-level validation
Cons:
-Breaks DRY philosophy in that you're generally repeating your database schema -In a sense breaks separation of concerns, because the query concerns of the controller and view frequently become the concerns of whoever is maintaining the repository -Determining what should be a repository and what should be returned as a raw associated ORM entity becomes an ambiguous art
To me it seems like all this stuff should be done at the ORM level, but Entity Framework has much fewer hooks than Linq to Sql does, yet Entity Framework tends to be regarded as being more robust, so it seems that this is by design, and that the designers of EF are in fact encouraging another layer. Are there any tools or anything that I could be using for this? Am I missing something?
I am currently using the 3-tier Repository pattern in my application. Actually it's the first time for me to implement a design pattern at all! i used to put all my code in the so called now presentation layer.
i want to implement data validation, for example, password should not be more than 10 characters and have to contain special characters. Should i put this code in the data access layer? but my data access layer contains methods that take the DTO as a parameter for example
[Code]....
and the same is for other CRUD operations (DELETE and UPDATE), so implementing such validation on the DAL would make me duplicate the code in each and every method that accepts the DataObject as a paramter. Same holds for the business logic layer where i am using it as a proxy between the presentation and the data access layers.
Eventually it has to use the same Data Objects as parameters. This only leaves me with one option which is to do the validation on the Data Object part. But i think this is not the essence of the respository pattern which states that the Data object class should only be a "container" class with no behavior.
I visited this Link to study about Factory design pattern.http://wiki.asp.net/page.aspx/310/factory/ But i am confused about it still. What i understood is that we must use an Interface to define a class .In the interface we will give the prototype of functions and later on we will define it in concrete class. Is that simple concept is Factory design pattern ?
I know what Singleton Pattern means and Abstract class means.What I wanted to know was how would this apply to real world.Could anyone give me any good example or simple explanation.Say I have a simple website, why would I use any of the above if any.Why would it simplify my architechture.
I am creating an authentication service. This service has one of the methods to validate username and password and return a status based on it.
The validation method has bunch of things to check before it can say user is valid. This method has a pseudo code similar to this:
If UserName and Password is correct
If User Account is Locked (due to invalid attempts)
{[code]....
As you can see there are lots of if else statements that I am writing. It looks more like a procedural programming rather than object oriented.How can I fit such kind of code in object oriented pattern?
I am trying to understand the fundamental differences between the Provider Model and Repository Pattern.
I have used the Provider Model in many many situations and am confident with it when designing applications. However, the more examples I encounter on the internet and asp.net evolution I keep coming across "Repository" Interfaces for classes that look like a Provider Model.
I have dug around a bit but all I can see is that they kinda do the same thing, or closely overlap by enforcing an inheriting class to adhere to a "contract" of implemented / abstracted methods etc...is there more to it?
i know some thing about the MVP pattern... but when you want to develop a project(web project) based on the MVP pattern from where we need to start... i mean which component we need to start developing first ... Model or View or Presenter... what are the points that we need to keep in mind....
We have an ASP.NET MVC site that uses Entity Framework abstractions with Repository and UnitOfWork patterns. What I'm wondering is how others have implemented navigation of complex object graphs with these patterns. Let me give an example from one of our controllers:
[code]....
It's a registration process and pretty much everything hangs off the POCO class Person. In this case we're caching the person through the registration process. I've now started implementing the latter part of the registration process which requires access to data deeper in the object graph. Specifically DPA data which hangs off Legal inside Country.
The code above is just mapping out the model information into a simpler format for the ViewModel. My question is do you consider this fairly deep navigation of the graph good practice or would you abstract out the retrieval of the objects further down the graph into repositories?
Does anyone have a working pattern for converting a GET-POST-GET pattern to asny?
I'm encountering the following issues:
1. You cannot mix Sync and Async action methods SubmitForm(), SubmitFormAsync(bool? confirm), SubmitFormCompleted() ... (because the resolver gets all confused ... it doesn't use the HTTP verb to decide who to target. BTW: I think that's poor design, or a bug)
2. Renaming the get method name to something else eg: SubmitFormConfirmation(), SubmitFormAsync(bool? confirm), SubmitFormCompleted() would be very awkward if it works ... because you have to doctor the <form markup to specify an action name.
3. You cannot give them all async names SubmitFormAsync(), SubmitFormAsync(bool? confirm), submitFormCompleted(), because the call just keeps malfunctioning. It sometime even behaves as if you are requesting a delete of something.
Can someone give an insight from an actually working sample.
