ClientDataTransferSubscriber is the function called when an event occurs in a data transfer initiated on the client -- it reads the voucher to verify this even occurred in a retrieval market deal, then, based on the data transfer event that occurred, it dispatches an event to the appropriate state machine.

ProviderDataTransferSubscriber is the function called when an event occurs in a data transfer received by a provider -- it reads the voucher to verify this event occurred in a storage market deal, then, based on the data transfer event that occurred, it generates and update message for the deal -- either moving to staged for a completion event or moving to error if a data transfer error occurs.

TransportConfigurer configurers the graphsync transport to use a custom blockstore per deal.

EventReceiver is any thing that can receive FSM events.

StoreGetter retrieves the store for a given id.