Glossary

Term Definition
Node Machine running all the components necessary for a working blockchain (including the Validator, the REST API, at least one transaction processor, and the PBFT algorithm itself). In this RFC, unless otherwise specified, it can be assumed that Node refers to the PBFT component of the machine.
Server Synonym for node.
Replica Synonym for node.
Validator Component of a node responsible for interactions with the blockchain. Interactions with the validator are abstracted by the Consensus API.
Block A part of the blockchain, containing some operations and a link to the previous block.
Primary Node in charge of making the final consensus decisions and committing to the blockchain. Additionally is responsible for publishing the blocks given to it by the Consensus API, and starting the consensus process.
Secondaries Auxiliary nodes used for consensus.
Client Machine that sends requests to and receives replies from the network of nodes. PBFT has no direct interaction with clients; the Validator bundles all client requests into blocks and sends them through the Consensus API to the consensus algorithm.
Checkpoint Mode when log messages can be garbage collected. Checkpointing is triggered when a certain number of blocks have been committed.
Checkpoint period How many blocks are published in between each checkpoint.
Consensus seal Proof that a block underwent consensus
Block duration How many seconds to wait before trying to publish a block.
Message Block, with additional information (see Message Types).
Working block The block that has been initialized but not finalized, and is currently being committed to.
Low water mark The sequence number of the last stable checkpoint.
High water mark Low water mark plus the desired maximum size of nodes’ message logs.
View The period of time of PBFT when the current primary is in charge. The view changes when the primary is deemed faulty, as described in View Changes.
n The total number of nodes in the network.
f The maximum number of faulty nodes.
v The current view number (how many primary node changes have occurred).
p The primary server number; p = v \mod n.