Architecture of Graph Module

Hama includes the Graph module for vertex-centric graph computations. Hama's Graph APIs allows you to program Google's Pregel style applications with simple programming interface.

Internals

The Graph APIs are implemented on top of Hama BSP framework. It consists of three major classes: VertexInputReader, GraphJob, and GraphJobRunner.

VertexInputReader: it is used for parsing and extracting the Vertex structure from arbitrary text and binary data.
GraphJob: the primary interface for a user to describe a Graph job to the Hama BSP framework for execution.
GraphJobRunner: the BSP program for performing the Vertex's compute() method.

GraphJob provides some additional Get/Set methods extending the core BSPJob interface for supporting the Graph specific configurations, such as setMaxIteration, setAggregatorClass, setVertexInputReaderClass, and setVertexOutputWriterClass. Rest APIs e.g., InputFormat, OutputFormat etc. are the same with core BSPJob interface.

GraphJobRunner

The GraphJobRunner is the BSP program which is performs assigned vertex computations and creates output.

LoadVertices

doInitialSuperstep and doSuperstep

Future Ideas and Challenges

List of Future Ideas and Challenges.