zk--preface(57)

Building distributed systems is hard. A lot of the applications people use daily, however, depend on such systems, and it doesn’t look like we will stop relying on distributed computer systems any time soon. Apache ZooKeeper has been designed to mitigate the task of building robust distributed systems. It has been built around core distributed computing concepts, with its main goal to present the developer with an interface that is simple to understand and program against, thus simplifying the task of building such systems.

Even with ZooKeeper, the task is not trivial. We start with basic concepts that will quickly make you feel like you’re a distributed systems expert. Perhaps it will be a bit disappointing to see that it is not that simple when we discuss a bunch of caveats（约束 ） that you need to be aware of. But don’t worry; if you understand well the key issues we expose, you’ll be on the right track to building great distributed applications.

Audience
Aimed at developers of distributed systems and administrators of applications using ZooKeeper in production.

Part I covers some motivations for a system like Apache ZooKeeper, and some of the necessary background in distributed systems that you need to use it.

斜体
Italic emphasis, new terms, URLs, commands and utilities, and file and directory names.

代码：
Supplemental material (code examples, exercises, etc.) is available for download at http://bit.ly/zookeeper-code.

ZooKeeper is the collective work of the Apache ZooKeeper community.

//权衡
trade-offs