Proposer
In the architectural framework of Distributed Systems and Blockchain Technology, a Proposer is a specialized role responsible for suggesting a value or a block of transactions to be appended to a shared ledger. The concept is central to various Consensus Mechanisms, ensuring that multiple independent nodes can agree on a single version of the truth without a central authority. In the classical Paxos Algorithm, the Proposer initiates the consensus process by sending a proposal to Acceptors, who then decide whether to adopt the value.
Within the context of Proof of Stake (PoS) networks, such as Ethereum, the Proposer is a Validator selected via a pseudo-random process to create a new block for a specific Slot Time. This selection often leverages a Verifiable Random Function (VRF) to ensure that the choice is both unpredictable and transparent, mitigating the risk of targeted Denial of Service attacks. According to documentation from the Ethereum Foundation, the Proposer collects transactions from the Mempool, packages them into a block, and broadcasts it to Attesters for validation.
The role of the Proposer is distinct from that of a Relayer or an Attester. While the Proposer builds the block, the Attester provides the cryptographic signatures necessary to confirm the block's validity. In some advanced protocols like MEV-Boost, the Proposer may outsource block construction to specialized Builders to maximize Maximal Extractable Value. Further technical specifications regarding proposer selection can be found in the Ethereum Consensus Specs.