Suvarna Garge (Editor)

Hector (API)

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Original author(s)
  
Ran Tavory

Preview release
  
none / n/a

Written in
  
Java

Stable release
  
0.7.0-23

Development status
  
Inactive

Operating system
  
Cross-platform

Hector is a high-level client API for Apache Cassandra. Named after Hector, a warrior of Troy in Greek mythology, it is a substitute for the Cassandra Java Client, or Thrift, that is encapsulated by Hector. It also has Maven repository access.

Contents

History

As Cassandra is shipped with the low-level Thrift (protocol), there was a potential to develop a better protocol for application developers. Hector was developed by Ran Tavory as a high-level interface that overlays the shortcomings of Thrift. It is licensed with the MIT License that allows to use, modify, split and change the design.

Features

The high-level features of Hector are

  • A high-level object oriented interface to Cassandra: It is mainly inspired by the Cassandra-java-client. The API is defined in the Keyspace interface.
  • Connection pooling. As in high-scale applications, the usual pattern for DAOs is a large number of reads/writes. It is too expensive for clients to open new connections with each request. So, a client may easily run out of available sockets, if it operates fast enough. Hector provides connection pooling and a nice framework that manages the details.
  • Failover support: As Cassandra is a distributed data store where hosts (nodes) may go down. Hector has its own failover policy.
  • JMX support: Hector exposes JMX for many important runtime metrics, such as number of available connections, idle connections, error statistics.
  • Load balancing: A simple load balancing exists in the newer version.
  • Supports the command design pattern to allow clients to concentrate on their business logic and let Hector take care of the required plumbing.

    • Availability metrics

    Hector exposes availability counters and statistics through JMX.

    Load balancing

    Hector follows two load balancing policies with the LoadBalancingPolicy interface. The default is called RoundRobinBalancingPolicy and is a simple round-robin distribution algorithm. The LeastActiveBalancingPolicy routes requests to the pools having the lowest number of active connections, ensuring a good spread of utilisation across the cluster. .

    Pooling

    The ExhaustedPolicy determines how the underlying client connection pools are controlled. Currently, three options are available:

    Code examples

    As an example, an implementation of a simple distributed hashtable over Cassandra is listed.

    References

    Hector (API) Wikipedia
    (Text) CC BY-SA