The base samplestore builds on the burst-samplesource with more concrete implementation of a samplestore that builds on the Fabric topology used by the Cell supervisor and workers. This is a simple samplestore that is used for testing and as a base for other samplestores. It does the heavy lifting managing the topology of scalable number of workers and the communication between them. It uses the samplesource which is the ETL pipeline each individual worker.
A scanning samplesource is a samplesource that simply iterates over the items it is transforming to Burst Brio instances. It abstracts the details of setting up a scan and iterating over each item and manages the interaction with the Cell workers, the pressing of the items into Brio instances, and the sending of the Brio instances back to the Cell workers. It is the base class for the synthetic samplestore and an internal Hbase scanner used by Yahoo.