如何在c#中实现三层架构

Question

提问by Tr?n Minh

I read many articles talk about 3 tiers architecture in c# but i see that:

我读过很多关于 c# 中的 3 层架构的文章，但我看到：

Almost use Bussiness Logic Layer(BLL) as a object mapping corresponding table in database. This BLL object has some methods like these:
+GetData(): return this;
+Update(this);
+Insert(this);
+Delete(this);
This BLL object calls corresponding DAL(Data Access Layer) to execute to corresponding table of database.
I think if with above methods, we can oly get a record and update it. But if we have got many records and want to put it into a dataset, how can we update all records changed? Must we use loop for all records to do that?
Moreover, in the database, there are many tables related to each other, so how can we put them into dataset, make relations and add, update, delete records like using BindingSourcewith a Comboboxand a DataGridView? And how can we seperate code in this situation?

几乎使用业务逻辑层（BLL）作为对象映射数据库中的对应表。这个 BLL 对象有一些这样的方法：
+ GetData()：返回这个；
+ Update(this);
+ Insert(this);
+ Delete(this);
该 BLL 对象调用相应的 DAL（数据访问层）执行到数据库的相应表。
我想如果用上面的方法，我们只能得到一个记录并更新它。但是如果我们有很多记录并且想把它放到一个数据集中，我们如何更新所有改变的记录？我们必须对所有记录使用循环才能做到这一点吗？
而且，在数据库中，有很多相互关联的表，那么我们如何将它们放入数据集中，建立关系并像使用BindingSourceaCombobox和a一样添加，更新，删除记录DataGridView？在这种情况下我们如何分离代码？

Answer 1

There are 2 cool project about three tier architecture in C#.

C#中有两个关于三层架构的很酷的项目。

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Answer 2

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The above describe a very simple architecture of a 3-tier model.

上面描述了一个非常简单的三层模型架构。

DAL (Data Access Layer) interacts with Database directly, so all the SQL operation are being done within DAL only.
BLL (Business Logic Layer) works like a mediator between DAL and the Presentation Tire.
No direct communication is allowed between DAL and Presentation Layer.
Although there is no physical presence of the Entity Layer, but Entity encapsulates all the information/data and passes it from one layer to the other.
So all the Database object name and the Database Schema is being restricted inside the DAL which gives an extra security layer to the application.
As Business rules/logics are being defined inside BLL, any update to business logic will not impact the DAL and the presentation layer

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This diagram describes an actual implementation of a 3-tier model.

此图描述了 3 层模型的实际实现。

Data Access Service and the Database Server can be hosted in single Server.
Mostly SQL Server 2000/2005/2008 or Oracle can be hosted on Windows 2000/2003 Server.
Business Server exposes all the operation through Web Service /Remoting/WCF.
A highly configured server with Windows 2000/2003 can be used to host the Business Service, or else Microsoft BizTalk Server also can be used for this.
Presentation Tier or the Client Consumes the Service exposed at Business Server by using the Proxy through http:// pipeline.
Client can be any standalone machine with the application is being installed in case of Desktop Application (Win-Form or Console Application), or having a Browser to run Web Application.
Data/Information are being encapsulated by entity and transferred from one location to another over network followed by all the network protocol.