Chapter 2. Basic Concepts 基本概念
Table of Contents 内容目录 www.shengfang.org

2.1. The Repository 仓库
2.2. Versioning Models 版本控制模式
2.2.1. The Problem of File-Sharing 文件共享的问题
2.2.2. The Lock-Modify-Unlock Solution 锁定－修改－解锁 解决方案
2.2.3. The Copy-Modify-Merge Solution 复制－修改－合并 解决方案
2.2.4. What does Subversion Do? Subversion怎么做的
2.3. Subversion in Action Subversion运作
2.3.1. Working Copies 工作拷贝
2.3.2. Revisions 修订版本
2.3.3. How Working Copies Track the Repository 工作拷贝如何追踪仓库
2.4. Summary 概要
This chapter is a slightly modified version of the same chapter in the Subversion book. You can read the Subversion book here: http://svnbook.red-bean.com/ .  本章基于Subversion手册做了些许修改，你可以在 找到SUBVERSION手册 www.shengfang.org

This chapter is a short, casual introduction to Subversion. If you're new to version control, this chapter is definitely for you. We begin with a discussion of general version control concepts, work our way into the specific ideas behind Subversion, and show some simple examples of Subversion in use. 本章是一个简短的，临时的SUBVERSION入门导论，如果你是刚接触版本控制，本章适合你。我们从讨论整个版本控制概念开始，顺着我们的说明进入在SUBVERSION之后的具体细节，并且展示一些简单的SUBVERSION实际使用例子 www.shengfang.org

Even though the examples in this chapter show people sharing collections of program source code, keep in mind that Subversion can manage any sort of file collection - it's not limited to helping computer programmers. 即使本章例子显示的是人们共享程序源码，但是请注意SUBVERSION可以管理任何文件，不仅仅是帮助计算机程序员而已 www.shengfang.org

2.1. The Repository 仓库
Subversion is a centralized system for sharing information. At its core is a repository, which is a central store of data. The repository stores information in the form of a filesystem tree - a typical hierarchy of files and directories. Any number of clients connect to the repository, and then read or write to these files. By writing data, a client makes the information available to others; by reading data, the client receives information from others. SUBVERSION是一个共享信息的集中管理系统，它的核心是仓库，它是数据的中心储备库，仓库用一种文件系统树的形式储存资料，一个典型的文件＆目录层次。许多客户端连接仓库，读学这些文件，通过写入数据，一个客户端做的信息对其他客户端也是有效的，读取数据，客户端也从其他那里接受资料 www.shengfang.org

Figure 2.1. A Typical Client/Server System 一个典型的客户端服务器系统

So why is this interesting? So far, this sounds like the definition of a typical file server. And indeed, the repository is a kind of file server, but it's not your usual breed. What makes the Subversion repository special is that it remembers every change ever written to it: every change to every file, and even changes to the directory tree itself, such as the addition, deletion, and rearrangement of files and directories. 这点是为什么有趣？到目前为止，看上去象一个典型的文件服务器的定义，实际上，仓库是文件服务器的一种，但不是你平常使用的类型，SUBVERSION仓库的特别之处在于它记住每个曾经写入它的改变；每个文件的修改，目录树本身的修改记录，例如增加删除重新整理文件和目录 www.shengfang.org

When a client reads data from the repository, it normally sees only the latest version of the filesystem tree. But the client also has the ability to view previous states of the filesystem. For example, a client can ask historical questions like, "what did this directory contain last Wednesday?", or "who was the last person to change this file, and what changes did they make?" These are the sorts of questions that are at the heart of any version control system: systems that are designed to record and track changes to data over time.

当一个客户端从仓库读取数据，它通常只是看到最新版本的文件系统树，但是客户端也有能力看到文件系统以前的状态，例如，一个客户端可以询问关于历史的问题，例如 上个星期三这个目录包含了什么 谁最后修改了这个文件，他做了什么修改 这一系列的问题是任何一个版本控制系统的核心问题，系统必须设计为记录和跟踪任何时刻的修改记录 www.shengfang.org