Architecture :: What Is The Use Of Aggregates In Domain Driven Design
Aug 7, 2010
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?
Assuming my application did not warrant a full blown DDD setup, would Repositories still be useful? I like the way they shield from implementation details (such as use of Entity Framework) underneath. However Repositories tend to be tied to Aggregate Roots (the concept is still a holy grail to me) by definition.
I suppose the question could also be put as such: if I have a typical 3-tier application, with a business layer facade consisting of "logical grouping" classes based on functionality (rather than aggregate roots as in DDD) such as TradingManager and ContactsManager, would it make sense to also create "logical grouping" repositories. Or perhaps a Data Access Object, which I believe is like a Repository without the aggregate root requirement. Of course I will still have a Model (EF POCOs) that will be passed up and down between the layers.
Also, is what I just described would be considered as a Transaction Script approach? It's certainly not DDD, and not Active Record. I'm not even sure if Active Record exists with EF4 like it does with Nhibernate.
I am trying to understand how others structure n-layered applications when they do not follow DDD.
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.
I'm doing some asp.net mvc coding using DDD. I have objects representing the business entities and service repositories that handle fetching and adding them. I'm new to this and as my application grows I begin to see a lot of secondary code that must run as a result of adding, deleting or changing my domain objects/data.
I'd like to make an event driven system where one action triggers other parts of code to run. For instance when I delete a user I want to be able to subscribe a number of other things to this action so they all are run when a delete takes place.
How have you coded your applications to handle these situations? How can I establish a reliable and coherent OO system for my problem? I already know about events and delegates but I'm more interested in coding techniques and nice practices.
the best practice for a designing a simple CRUD application with some screens updating various tables (like admin pages to maintain static data for an application). the simplest way would be to drag a data grid/gridview, bind it to a dataset and use a data adapter for CRUD operations. but if this application needs to be scalable, lets say to add any extra UI/business logic in future, then is there any design pattern that can with this? should I be using an object data source control and bind it to business objects instead? or are there any better ways of doing it? should I build a complete layered application or will that be overengineering for this requirement?
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.
know whats is happening and why its throwing an error (it does not find GetBrokenRules method because its List) but the reason i posted this question here is to ask for a better design, can anybody guide me here please?i am working on Facilities class (List..../Building/Floor) rror:Error 3System.Collections.Generic.List' does not contain a definition for 'GetBrokenRules' and no extension method 'GetBrokenRules' accepting a first argument of type 'System.Collections.Generic.List' could be found (are you missing a using directive or an assembly reference?)
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.
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?
what is considered a many-to-many relationship in a domain model class ? I mean how to implement a many-to-many relationship in a domain model class ? In SQL this is represented by a link table between two table but how this is represented in a domain model driven application ?
My MVC ASP.NET web application is split up like this:
Web Application Layer Views
[Code]....
Now, I have a view in the database called "EquipmentWithCableDetails", which contains additional useful information with the equipment details - so I create a class to model that view (in order to be able to read from it). In the code I have that works with that new class, I want to display the EquipmentDescription - but that property only exists on the Equipment class.
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 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?
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?
how a large ASP.NET webapplication can be structured / designed with "subwebs" !? In other words I want to structure a large web-application where I have a solution with more web-application projects. These projects are more or less independent "modules". One project should be a kind of frame application with shared masterpages, an shared sitemap and and a shared authentication. Later it should also be maybe possible also to integrate loosely older websites (which where written in classic ASP. ASP.NET 1.1, ASP.NET 2.0), but this not so important at the moment
I would like to provide my client with a aspx pages, with code behind provided, etc. But in some cases they will want to write their own markup - I'm thinking of having 2 directories [siblings of each other], one for the pages I provide, and the other for their custom markup. At page serve time, check to see if the client wrote their own markup and if so use it. Otherwise use the default provided.
In a nutshell I would like for my clients to be able to modify the pages I provide, but if they blow it up have a very easy way to back it out. Or to put it in a more positive light, allow them to override my pages easily.
