Giraph builds upon the graph-oriented nature of Pregel but additionally adds fault-tolerance to the coordinator process with the use of ZooKeeper as its centralized coordination service.
Giraph follows the bulk-synchronous parallel model relative to graphs where vertices can send messages to other vertices during a given superstep. Checkpoints are initiated by the Giraph infrastructure at user-defined intervals and are used for automatic application restarts when any worker in the application fails. Any worker in the application can act as the application coordinator and one will automatically take over if the current application coordinator fails.
The Silk framework is a tool for discovering relationships between data items within different Linked Data sources.
Data publishers can use Silk to set RDF links from their data sources to other data sources on the Web.