Architecture :: Provider Model Versus Repository Pattern
Feb 4, 2011
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?
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Jul 8, 2010
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?
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Dec 21, 2010
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.
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Jan 19, 2010
When I first heard about ASP.NET MVC, I was thinking that would mean applications with three parts: model, view, and controller.
Then I read NerdDinner and learned the ways of repositories and view-models. Next, I read this tutorial and soon became sold on the virtues of a service layer. Finally, I read the Fluent Validation documentation, and I'll be darned if I didn't end up writing a bunch of validators.
Tonight, I took a step back and thought about what had become of my project. It seems to have become the victim of the design pattern equivalent of "feature creep". Somehow I'd gone from Model-View-Controller to Model-Repository-Service-Validator-View-ViewModel-Controller. You want loosely coupled and DRY? We got your loosely coupled and DRY right here! But I'm wondering if this could be a case of too much of a good thing.
Am I right to be concerned? Or is this actually not as crazy as it sounds? On one hand, it seems crazy to have so many layers. On the other hand, every layer has a clearly defined purpose that makes sense to me. Have your MVC applications turned into MRSVVVMC apps too? If not, what do they look like? Where's that right balance?
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Oct 13, 2010
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?
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Dec 8, 2010
i'm new to asp.net MVC, and I'm trying to understand the service/repository pattern and how to best implement it.
I've followed the MVC Music store tutorial, and it suggests that the public partial class ShoppingCart implements an AddToCart method looking like this:
[Code]....
Now if I would like to use the service/repository pattern in a correct way, should I just replace the row "storeDB.AddToCarts(cartItem)" with something like cartService.AddToCarts(cartItem) and then just save the added row by calling cartService.Save() instead of shopDB.Save()? The methods AddToCart(...) and Save() in cartService then calls the repository that does the actual saving.
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Mar 8, 2011
I've been using MVC for the last year and unfortunately I am stuck adding features to an existing web forms site. The site makes heavy use of inline SQL and it is kind of all over the place. Using an ORM is not going to happen either and wouldn't address the problem of keeping queries all in one place.
Can the Repository Pattern and Service layers also work well with classic asp.net web forms?
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Feb 15, 2010
I am building an application using asp.net mvc, DI, IoC, TDD as a bit of a learning exercise.
For my data access I am using the repository pattern. Now I am looking at membership and how this can work with the repository pattern. I am currently using a Linq to Sql repository but don't want to be tied to SQL Server for membership.
Secondly, I am looking to split out membership into a number of services:
AuthenticationService - identify the user
AuthorizationService - what can they do
PersonalizationService - profile
The personalization service will be what really defines a "customer" in my application and each customer will have a unique id/username that ties back to the AuthenticationService - thus, allowing me to use the default ASP.NET Membership provider, roll my own or use something like Open ID.
Is this a good approach? I don't want to reinvent the wheel but would rather these important parts of my application follow the same patterns as the rest.
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Oct 18, 2010
I am sort of using a repository pattern to extract information from a database. I have two classes, report and reportRepository.
The trouble I have is that since reportReposity has to fill in all the details for the report object, all the members in the report have to be publicly accessible.
Is there a way so that I can ensure that only the repository class can access some of the methods of the report class and only it can set some of the properties that other classes cannot, sort of like what friend does in c++. Or is there a completely different way of handling this situation?
I am using C# in ASP.NET 2.0
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Nov 2, 2010
I'm working on adding an HtmlHelper for pagination, but I am unsure where the proper and/or most beneficial place to put certain parts of the pagination code from a performance and maintainability standpoint.
I am unsure if the Skip(), Take() and Count() portions of Linq to SQL data manipulation should live within the repository or the controller.
I am also unsure if their order and where they are used affects performance in any way.
If they live within the repository from my understanding this is how it would work:
1. I would pass the pageIndex and pageSize as arguments to the repository's method that grabs the data from the database.
2. Then grab the full data set from the database.
3. Then store the count of TotalItems of that full data set in a variable.
4. Then apply the Skip() and Take() so the data set retains only the page I need.
5. Display the partial data set as a single page in the view.
If they live in the controller from my understanding this is how it would work:
1. I would grab the full data set from the repository and store it into a variable inside of the controller.
2. Then get the count of TotalItems for the full data set.
3. Then apply the Skip() and Take() so the data set retains only the page I need.
4. Display the partial data set as a single page in the view.
Inside the controller (I realize I will incorrectly get the page count here and not TotalItems):
[code]....
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Jan 17, 2011
i am using EF4 and StructureMap in an asp.net web application. I am using the repository/unit of work patterns as detailed in this post. In the code, there is a line that delegates the setup of an ObjectContext in global.asax.
EntityUnitOfWorkFactory.SetObjectContext(() => new MyObjectContext());
On the web page code-behind, you can create a generic repository interface like so ...
IRepository<MyPocoObject> ds = ObjectFactory.GetInstance<IRepository<MyPocoObject>>();
My question is what is a good approach to refactoring this code so that I can use more than one ObjectContext and differentiate between them in the code-behind? Basically i have two databases/entity models in my application and need to query them both on the same page.
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Jun 12, 2010
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?
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Apr 15, 2010
I need some guidance for an application I am working on. I have searched the web and the forum and found parts that answer my questions but I want to do this correctly. My solution uses LINQ to SQL to model the db and I have a repository that is querying my db everytime a controller needs to get some data for the view. I am initially anticipating a maximum of only about a few hundreds hits per day (if that). The website is a directory, with listings and requires a search functionality.
1. What options should I consider to avoid having my repository query the db everytime
2. The site contains a 'search' option, how can I implement this against my repository?
I guess I'm really looking for someone to point me in the right direction. So far I've looked at 'caching' the LINQ to SQL model and Lucene.NET but both seem overkill or am I missing the point?
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Mar 2, 2010
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.
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Sep 26, 2010
I've been reading recently about EF4, and how to build an architecture for asp.net web forms application using it.
I explored using POCOs (self tracking entities), with WCF, but found out that my application will be deployed on a single box (i.e. one tier), so I started reading about logical separation of layers, and came up with the following solution:
DAL layer that contains EDMX model and EF APIs, and also generated context object.Entities DLL that holds all generated POCO entities using ADO.NET POCO entity generator. (for persistence ignorance, and decoupling entities from DAL).Business layer that contains a façade for each related group of business functions, the façade will be aware of and using DAL layer. And in each function, it will initiate context and uses different entities to carry out specific job (i.e. function).UI layer that only calls the business layer façade classes. With no awareness of DAL, but it will be aware of entities (i.e. using entities DLL), as the business layer will return results basically as entity collections.
I want to know what you think about this architecture.
I also read about an architecture that uses repository and unit of work patterns, but what I understand that context object is already implementing a UOF pattern, and also object sets are implementing repository pattern (correct me if I'm wrong), so the only advantage of using additional abstraction over them is to make the business layer communicates to my classes, not EF classes, and this is good only if the DAL strategy might change (i.e. by using another tool other than EF, which is not my plan).
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May 31, 2010
I read some article about unitOfwork and repository but i'm still confused about how they interact, and how to use them in the right way.
I'm using an addressbook project to practise on patterns (even if , likely, patterns are not usefull) without any ORM framework for persistence.
My domain objects are (at now) : AddressBook (acts as an application controller), Contact (contains information about each contact in the address book), ContactGroup (mantain collections of contact).
Should i have to use distinct repository object for contact ad contactgroup?
I thought to use a UnitOfWork for the operation about the adding/removing contact to group : the user can add existing contact to a group, create a new contact while adding it to the group or remove contact from group.
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Jan 26, 2011
Just wondering, in an ASP.NET MVC3 environnement with entity framework. Should the Unit of Work point to the service layer or the repository (and then the repository point to the service layer) ?
Ive saw two example:
* One where the unit of work and repository both have an instance to the service layer..
Link: Entity Framework 4 CTP 4 / CTP 5 Generic Repository Pattern and Unit Testable
Doesn't use a service layer but its obvious that one could be use in that case.
* Second where the unit of work have an instance to the repository which have an instance to the service layer..
[URL]
What would be better ?
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Apr 1, 2010
what is the difference between these two patterns?
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Jun 1, 2010
the more i read about pattern the more i get confused!
In particular i'm trying to get the relationship between Registry and Repository.
Is it correct to say that a possible implementation of a Registry uses a Factory to return an appropriate Repository which, in turns, uses an underline DataMapper to performe the CRUD operations against a database?
If no, which kind of relationship exists between repository and registry ?
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Feb 15, 2011
I've got a multi level dependency chain in my object model: An organization has the following children relationships:
Organization
.CompetitionGroups
.CompetitionGroups.Venues
.CompetitionGroups.Competitions
.Divisions.Games
.Divisions.Games.Participants
.Divisions.Games.Participants.GameSegments
.Divisions.SubDivisions...
.Divisions
.Teams
.Teams.Players
.Teams.Participants
.Teams.Participants.GameSegments
.VenueDates
This is just a glimpse at the object model, but it's focused on the complexity of the relationships and lists. What I can't really get is what's the best way to factor my repository interfaces, given the requirements to do a unit of work. For example, to create a game, you'll need a venuedate and two participants. Does that mean the GamesController should require an IGameRepository, an IVenueDateRepository, and an IParticipant repository? Should they be rolled into one repository?
Also, what about in the consumption cases? For example, to display a signle team's schedule, you'll need all of the Participants for that Team, all of the Games for that participant, and all of the GameSegments for the participant. If those are factored into individual repositories I can't see how you can do efficient queries. Does that mean you have Repositories specifically focused on different cases? for example:
public interface IScheduleRepository {
public ICollection<Game> GetScheduleForTeam(Team team);
// More consumption methods
}
public class ScheduleRepositry : IScheduleRepository {
public ScheduleRepository (ModelContext context) {
// Do stuff with context
}
public ICollection<Game> GetScheduleForTeam(Team team) {
return (
from p in context.Participants
where ((p.Game.VenueDate != null) &&
(p.TeamId == team.Id))
orderby p.Game.VenueDate.StartTime
select p.Game).ToList();
}
// more consumption methods
}
public interface IGameRepository {
public void AddGame(Game game);
// More crud methods
}
// Not showing games repository
public class GamesController : Controller {
public GamesController (IGameRepository gamesRepo,
IVenueDateRepository venueDateRepo,
IParticipantRepository participantRepo) {
// do stuff with repos here
}
[HttpPost]
public ActionResult AddGame(Game game) {
// Skipping validation logic
// this?
VenueDate = venueDateRepo.Add(game.VenueDate);
foreach (Participant p in Game.Participants)
{
participantRepo.Add(p);
}
Game = gamesRepo.AddGame(game);
// or this?
// how would the game repo know to persist
// the children elements? is that tight coupling?
Game = gamesRepo.AddGame(game);
}
// more consumption methods
}
My question is I don't yet understand to what degree factoring your repositories make sense based on a connected object model. I'd love to get some advice here.
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Dec 25, 2010
recently i've studied on ADO.NET's Entity Model Framework and say 'wow' as ORM is one of the fevourite pattern i practice..but suddenly i've come to an ambiguous situation when i'm going to start. i usually follow the following 3-tier architecture..
1. UI Layer
2. BLL - business logic layer
3. DAL - Data Access Layer
a. DTO / DAO
b. Gateway (contains the sql query/stored procedure and connection with DB)
now when i'm going to use the Entity Model Design,where the DBML/ .edmx File should be placed? Because many a times i'm using the DBML file as DTO because of the mapped objects.. in the same time, sometimes DBML ( .edmx file in .NET 4.0) contains CRUD methods and stored procedured method as well as methods with different selection operations,- which should be in Gateway. so where the .edmx file should be placed !?!! IN DTO namespace !? or in Gateway namespace!
moreover sometimes there is no need for the BLL which breaks the rules of inter-layer-communication (UI > BLL > DAL.Gateway)! what makes me confuse is, what should be the ideal n-tier architecture when i'll use the ADO.NET Entity Model Design Framework
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Sep 17, 2010
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.
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Mar 22, 2010
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?
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Jun 9, 2010
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.
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Dec 29, 2010
What is the approach? calc: BL vs. DB?
Using Asp.net3.5/ sql2005.
What is the approach? What should calculate in the database and what to implement in the business lyre??
If I will calculate in the db - I will have less round trips and less resources on the server side host - but less flexible programmatically side..
When to use object oriented programming and when to implement the calculation on database - when what I am looking for is first performance.
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