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Apache ZooKeeper Essentials

You're reading from   Apache ZooKeeper Essentials A fast-paced guide to using Apache ZooKeeper to coordinate services in distributed systems

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Product type Paperback
Published in Jan 2015
Publisher
ISBN-13 9781784391324
Length 168 pages
Edition 1st Edition
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Author (1):
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Saurav Haloi Saurav Haloi
Author Profile Icon Saurav Haloi
Saurav Haloi
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The ZooKeeper data model


As defined by the ZooKeeper wiki, ZooKeeper allows distributed processes to coordinate with each other through a shared hierarchical namespace of data registers. The namespace looks quite similar to a Unix filesystem. The data registers are known as znodes in the ZooKeeper nomenclature. You can see examples of znodes in the following image:

A ZooKeeper's hierarchical namespace

Here, you can see that znodes are organized hierarchically, much like a tree, as a standard filesystem. Some important points to take note of are as follows:

  • The root node has one child znode called /zoo, which in turn has three znodes.

  • Every znode in the ZooKeeper tree is identified by a path, and the path elements are separated by /.

  • The znodes are called data registers because they can store data. Thus, a znode can have children as well as data associated with it. It's analogous to having a filesystem that allows a file to also be a path.

The data in a znode is typically stored in a byte format...

You have been reading a chapter from
Apache ZooKeeper Essentials
Published in: Jan 2015
Publisher:
ISBN-13: 9781784391324
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