NoSQL: Database for Storage and Retrieval of Data in Cloud by Ganesh Chandra Deka

Author:Ganesh Chandra Deka
Language: eng
Format: azw3, epub, pdf
Publisher: CRC Press
Published: 2017-05-19T04:00:00+00:00

Figure 10.9

Zookeeper architecture.

Zookeeper has a file system-like data model, referred to as “znode.” Just like a file system has directories, znodes are also directories, and they can have data associated with them. The znode can be referenced through absolute path separated with a slash. Each server in the ensemble stores the Znode hierarchy in the memory, which makes the response quick and scalable as well. There are three types of znodes: the Persistence znode, which is alive even after the client is disconnected; the Ephemeral znode, which is active only as long as the client is connected and is deleted automatically once the client disconnects; and the Sequential znode, which has a 10-digit number attached to it at the end. The Sequential znode can either be persistence znode or ephemeral node.

10.5.3Apache Ranger

Ranger is a framework that enables, monitors, and manages comprehensive security across the Hadoop platform (Apache Incubator™, 2016). It provides a centralized security administration using REST APIs and UI. Ranger provides support for different types of authorization control like role-based control and attributed-based control. It provides standardized security across all Hadoop components. Using the administration console of Ranger, we can easily create and manage policies for accessing a resource like file, folder, or database access for a particular user or group of users. We can also enable audit tracking for having more control over the environment. Ranger supports authorization for Hive, HBase, Solr, and many more Hadoop components.

Ranger architecture is shown in Figure 10.10. The Ranger portal is the interface for security administration. The admin can create and update policies using the portal. These policies are then stored in the policy data store. The policy data store can be HDFS itself or any other RDBMS (Hortonworkscom, 2015). Ranger plugins are nothing but lightweight java components which are embedded within the Hadoop components on which security policies need to be enforced (White, 2015). The plugins pull policies from Ranger Policy Server. Every request sent to component is intercepted by the plugin and checked against the policy. Plugins also send audit data; data that is collected from the user request to Ranger Audit Server in a separate thread. These data are then stored in HDFS, RDBMS, or log4j.

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