什么是N层架构？ [英] What is N-Tier architecture?

问题描述

我最近看到不少开发商招聘职位，其中包括一个句子读取或多或少这样的：必须有N层架构经验或必须能够开发N层应用程序。

I've seen quite a few developer job postings recently that include a sentence that reads more or less like this: "Must have experience with N-Tier architecture", or "Must be able to develop N-Tier apps".

这使我问，什么是N层架构？如何来获得经验呢？

This leads me to ask, what is N-Tier architecture? How does one gain experience with it?

推荐答案

维基百科：

在软件工程中，多层
  架构（通常被称为
  n层体系结构）是
  客户端 - 服务器体系结构，其中，
  的presentation，应用
  处理和数据管理的
  逻辑上独立的进程。对于
  例如，使用的应用程序
  中间件服务的数据请求
  用户之间和数据库使用
  多层体系结构。最多
  wides $ P $垫使用多层的
  结构指的是三层
  架构。

In software engineering, multi-tier architecture (often referred to as n-tier architecture) is a client-server architecture in which, the presentation, the application processing and the data management are logically separate processes. For example, an application that uses middleware to service data requests between a user and a database employs multi-tier architecture. The most widespread use of "multi-tier architecture" refers to three-tier architecture.

这是值得商榷的层次，真正重要，但在我看来，这需要至少跨越进程边界。否则，它被称为层。但是，它并不需要在物理上不同的机器上。虽然我不建议这样做，你的可以的主机上的同一个盒子逻辑层和数据库。

It's debatable what counts as "tiers," but in my opinion it needs to at least cross the process boundary. Or else it's called layers. But, it does not need to be in physically different machines. Although I don't recommend it, you can host logical tier and database on the same box.

修改：一个含义是，presentation层和逻辑层（有时也被称为业务逻辑层）需要跨机器边界跨线有时在不可靠，速度慢，和/或不安全的网络。这是简单的桌面应用程序非常不同的地方在同一台机器上的数据作为居住文件或Web应用程序，你可以直接访问数据库。

Edit: One implication is that presentation tier and the logic tier (sometimes called Business Logic Layer) needs to cross machine boundaries "across the wire" sometimes over unreliable, slow, and/or insecure network. This is very different from simple Desktop application where the data lives on the same machine as files or Web Application where you can hit the database directly.

有关n层编程，你需要某种形式的所谓数据的形式进行传输，以打包的数据，并驾驶它们通过线路。 .NET的的DataSet类或Web服务协议一样的SOAP 少数这样尝试过线飞的对象。

For n-tier programming, you need to package up the data in some sort of transportable form called "dataset" and fly them over the wire. .NET's DataSet class or Web Services protocol like SOAP are few of such attempts to fly objects over the wire.

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