Architecture :: Design Which Have A Few Layers:Common, DataAccess, BusinessLogic,Operational?
Jun 24, 2010
It's appreciated if you could share your thought.I have seen a e-commerce website design which have a few layers:Common,DataAccess,BusinessLogic,Operational.In the Common layer,it includes all the classes with only attributes and properties,no methods nor data access codes here.
In the DataAccess layer,there is a class for each action per class in the Common layer.For example,
a class for the Select action of class A of Common layer,
a class for the update action of class A of common layer,
a class for the Select action of class�B of Common layer,
etc...
Is this a design I could use for a potential high trafic website?What's the pro and con of this design.
I am thinking to use entity model as DAL, how should I create the BLL then? What kind of datasourceobject should I use in the asp pages?
I am looking for best practice to use Entity framework 2 in the three layers design. I had experience at dataset with three layers design.
Should I use objectdatasource at the pages for gridviews? My guess is that entitydatasource by passed the BLL which is not good, so the only option left is the objectdatasource.
Could and should my BL object inherit those entity model in the DAL, so I dont need to recreate their object's property?
While designing (and then implementing) a layered application:
Is it correct to use the same ORM objects accross all layers? (which would go against encapsulation).
Or the presentation, business and data layer should each have their own objects? (which would lead to lots of code repetition).
e.g. (just to illustrate the question): if one uses Linq to SQL in the Data Layer and Visual Studio's O/R designer to generate the ORM objects, are those objects supposed to be used in the Business and Presentation Layers as well.
i.e.: Are the objects associated with the entities that the application handles a crosscutting issue?
I have three layers like UI, business and data access in my asp.net web application project. If I pass say a company code from the UI to the business to the data access and I query the company details like company name, address, phone etc from the database using sqlhelper executedataset() which wil return me a dataset. Then how do I pass these company details back to the UI layer. Is it correct to just pass the datatable object to the business and UI.
I'm trying to create my first Asp.Net application from scratch. Tried to create this post in some of the other forums but I couldn't find a better place.
So, as the title says, I'm having trouble trying to model my application. I'm like an OOP newbie. I'll show my classes first and then I'll write my questions.
Model Layer
public class User { private int id; public int Id { get { return id; } set { id = value; } } private string login; public string Login { get { return login; } set { login = value; } } private string password; public string Password { get { return password; } set { password = value; } } } Data Access Layer public class BasicDAL { private SqlConnection connection; //>>Returns a new connection to the database public SqlConnection GetConnection() { //>>If connection is active close it before starting a new one if (connection != null) if (connecion.State != ConnectionState.Closed) connection.Close(); connection = new SqlConnection("MyConnectionStringHere"); return connection; } } public class UserDAL : BasicDAL { //>>Insert a new user public void Insert(User user); { /* Insert into DB */ } //>>Authenticate user login with its password public void Authenticate(User user); { /* Authentication code here */ } } Business Logic Layer
[Code]....
So, model layer is pretty simple. Just a user representation. On the Data Access Layer I have a basic class with a GetConnection method. All DAL classes will extend this one.
My first problem lies on Business Logic Layer. With the above scenario, I've placed the same methods that I placed at the DAL. BLL methods would call DAL. As simple as that but I believe It is not the best way to do it, is it? How can I improve those classes?
Also, I have to "try..catch" blocks. That's because I can't find good places for it. I mean, if I place a try..catch on GetConnection method, for instance, how my ASPX page would get this error? How my ASPX page can tell the difference between "database offline" and "sql syntax error" when executing "userBll.Insert(newUser);".
My problem is mainly placing the exception handlers. I understand I would probably have to change return type of some methods. I didn't change because I believe that will have something with the exception handlers.
Btw, please assume I can't use TableAdapters and stuff like that. I would like to create all layers by myself.
In my application, I'm binding a Collection of Supervisor type, which I'm feeling that it is an additional overhead. Becuase I only want his ID. So binding an object collection to the dropdown which seems no worth.
I have a quick question in regards to testing my validation. I have been looking through a few MVC examples and have noticed the 'Validating with a Service Layer' tutorial which is pretty nice. It discusses how to abstract your code out etc..My question is, that they have validation occuring in the service layer, if errors occur, the error + message then gets added to a model state dictionary.Now i want to test my model to make sure my business rules are being applied to it, but with this approach, for starters, the Validation method is not in the interface. Now, if the validation method was in the interface, during testing you would have to re-implement the validation on the testing side.Am i missing somthing? Where should your validation code go? I feel like it should go in the model, but then i have to track the errors on the model side.
I'm trying to write a web app using 4-tier design pattern ( Data Store, DAL, BLL and UI). Among other things this app would also implement a forum.
Suppose I want to move a thread from one forum to another. In order to do this, UI layer must pass down to other layers the ID of a thread and the ID of a forum to which I wish to move this thread ( UI would pass these parameters by calling method A in BLL layer and A would in turn call method B in DAL layer... ).
a) Now should one of the bottom layers provide some sort of checking mechanism to ensure that the two ID arguments supplied by UI layer really represent an existing thread and an existing forum or is it the responsibility of UI layer to provide valid ID values?
EDIT:
I would consider the ability to pass invalid IDs a bug.
Should non existing ID be considered a bug just in the case of moving a thread, or also in the case of displaying a thread. Thus when user navigates to page Showthread.aspx?ID={0}, if query string parameter ID references non existing ID, If none of the layers check for the validity of ID, then GridView simply won't display any
"But in this case it doesn't look like the ids are in any sort of list. If they were one could only assume that this would never happen as I assume the lists would be populated by a stored procedure or a DAL procedure that pulls all valid IDs."
But even if user chooses IDs from a set of list, by the time it posts the page back, the DB table containing this ID could be changed in the mean time by admin or whomever?!
I'm a junior programmer, i do not get the concept of MVC! My method of coding is seperating my application design into 3 layers:
Presentation Layer Business Layer Data Access Layer
I find it very practical to a junior developer or at least to me, so i do not really get the point of MVC since i believe MVC just tries to separate logic from UI. Right?
I decided to have this book to help me have a better idea on code design:
I doubt how to implement the layers FACADE, BLL and DAL, using DTOs specialized .. where:
public class ClassA { private int _Test1; public int Test1 { get { return _Test1; } set { _Test1 = value; } } } public class ClassAB : ClassA { private int _Test2; public int Test2 { get { return _Test2; } set { _Test2 = value; } } } public class ClassAC : ClassA { private int _Test3; public int Test3 { get { return _Test3; } set { _Test3 = value; } } }
In the database, there is the 3 tables, as described above.how do I implement the facade, bll and dal? only one class for 3 DTOs?
i want to create a centralised business or Service authendication architecture in .net. for example, we have a clients like c1, c2, c3, c4, ... etc. everybody logins seperatly as well as grouply. ie, if client "C1" logins [with login authentication] he can access c2 , c3, c4 also without login authendication. So its like a google. if we enters gmail account, we can access orkut, picasa like that.. i need the cetralised architecture.
And, client "c1" seperately asks seperately how will be the authendication architecture.
so give me the single solution for both these two scenarios. how will be the architecture for these two and how is the Data Base (Login) Structure.
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
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 am try to create architecture design for WCF service.
We have WCF service that we have to expose to third party so then can request with xml and get back xml response.
The wcf service should do the following:
- Accept the request call with xml
- Check xml against the schema
- Parse the xml
- Authenticate the incoming xml by username and password that will be in xml
- Send back the response
If anybody can let me know what kind of design I can use or is there any pattern available that I can take it and then extend it as per my requirement.
designing Business Objects. What a business object class can contain ?
I have looked many sample codes and articles. Some only use properties in them. Some use private members, properties and constructoers. As more I am reading becoming more confuse.
Some sample codes that I checked were making functions in BO classes as well. what a BO class should contain and what is its purpose. Should there be functions in them as well ? If yes how they can be differentiated from Business Logic class functions.
All the users of my system get a common Id (SystemUserId). There are predefined roles/groups in the system. One user can be belong one or more of these groups. We are populating the menu/dashboard at runtime according to logging credentials.All common details (properties) of group are stored in main table (SystemUser) and specialized details are stored in relavant tables.(Teacher/Student). My solution already has classes called, SystemUser, Teacher & Student.
Problem:My system should support new group addition. (eg-: Auditor)This should support new properties to be added to SystemUser/Teacher/Student or any other new group added by the Customer at runtime.
modules is being used for some sites when they are developing. what is this module. for example, this sites has some modules; membership module,comment module etc.Are modules a diffrent application that is added to site later, or they talk about httpmodules?
also, how can i begin this module design and coding?
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?
how to design following small webproject and database .i am totally new in this area.
I need to quickly develop a system so that everyone can access the status of the job going online into the system
Activities
Move the job between work centers when it's completed.
Transfer button. So when design is done we should be able to click the transfer button and move the job from Design to Procurement
Here are the work centers.
plan cerement TST Shipped Each work center should have due dates User will have to update manually due date for each work center and this will be different for each job.
I want to know what is the advantages of using aggregates in c# for design patterns.
suppose i have tree tables
Member(M_Id,M_Info)
Bid(B_Id,B_Info,M_Id,Item_Id)
Item(Item_Id,Item_Info)
"One member can place more than one bid on more than one item."
so there is one to many bidirectional association between Bid and Member table.
And one to many association between bid and item table Now According to defination of aggregates in this case Item table is the root of aggregate item and item has aggregation with bid table.
and bid table holds unidirectional reference to member table and hence only bid table has access over member table.
But ultimately this will also map in database same as without using aggregate then what is use of aggregates?
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 have a ordinary Category/Product database relationship Design structure.
Now i wish to add a sub category to this architecture.
for example, Cloths Category needs to be sub divided - Women,Men,Children categories.Also what about other Ctegories such as: Car,this also has sub divisions: Model,Type.
My Products table contains ProductName field together with generic field for Size,Colour and Price fields.
How do you therefore incorporate this sub division into the existing Category/Product relationship model and is there a model example?
