In this chapter, we will learn about some more advance coding on topics such as administrative tasks; available interfaces, classes, and exceptions in HBase; writing a MapReduce for HBase; and operations on HDFS. We will also discuss details on REST and Thrift API services and other advance topics such as coprocessors, bloom filters, and available HBase tools for value addition.
In this chapter, we will cover the following topics:
- Interfaces, classes, and exceptions in HBase
- Java code for performing administrative tasks
- Data operation codes
- MapReduce in HBase
- REST/Thrift web service introduction
- Advance concepts in HBase
- Information about some add-on projects
Interface is a set of abstract methods. A class in Java implements an interface and inherits the abstract methods of the interface. It is not a class. Writing an interface is the same as writing a class. A class tells us about the attributes and behaviors of an object. An interface contains behaviors that a class implements.
Class is a template/blueprint that describes the behavior that an object supports.
Exception is a problem that arises during the execution of a program.
Here is the list of some packages to be used in Java code:
org.apache.hadoop.hbase: This package contains a base class for HBaseorg.apache.hadoop.hbase.backup: This package contains classes related to backup tasksorg.apache.hadoop.hbase.client: This package contains a client-related classorg.apache.hadoop.hbase.codec: This package contains theCodecinterfaceorg.apache.hadoop.hbase.coprocessor: This package is used to write coprocessorsorg.apache.hadoop.hbase.exceptions: This package contains the predefined exception in HBaseorg.apache.hadoop.hbase.filter: This package provides a list of filtersorg.apache.hadoop.hbase.http: This package contains HTTP functionalitiesorg.apache.hadoop.hbase.io: This package contains I/O-related methodsorg.apache.hadoop.hbase.ipc: This package contains methods related to RPC connectionorg.apache.hadoop.hbase.mapred: This package contains MapReduce-related methodsorg.apache.hadoop.hbase.mapreduce: This is the newer MapReduce package, which provides HBase MapReduce I/O formats, a table indexing MapReduce job, and utility methodsorg.apache.hadoop.hbase.master: This package is used while interacting with the masterorg.apache.hadoop.hbase.monitoring: This package exports methods for monitoringorg.apache.hadoop.hbase.regionserver: This package is used when interacting with RegionServersorg.apache.hadoop.hbase.rest: This package provides REST APIorg.apache.hadoop.hbase.security: This package is used for tasks related to securityorg.apache.hadoop.hbase.snapshot: This package is used for backup and snapshotorg.apache.hadoop.hbase.thrift: This package provides Thrift servicesorg.apache.hadoop.hbase.tool: This package provides miscellaneous toolsorg.apache.hadoop.hbase.types: This package provides the definition and implementation of HBase's extensible data type APIorg.apache.hadoop.hbase.util: This package provides utilitiesorg.apache.hadoop.hbase.zookeeper: This package is used for tasks related to ZooKeepers
Note
All the important packages, interfaces, and a list of the updated APIs can be found at http://hbase.apache.org/devapidocs/index.html.