polkadot prezo
Post on 23-Jan-2017
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What does it provide?
Pooled securityall constituent chains of our community guaranteed
Trust-free transactionsconstituent chains can send transactions to each other
How does it work?
Relay-chainthe top-level which coordinates consensus and
transaction delivery between constituents
Parachainsconstituent chains which gather and process
transactions
Basics of the Relay-chain
No functionalityno external transactions, no smart contracts
Fees leviedfees paid for voting/movement of tokens between
parachains
Governance of the Relay-chain
TBDno big decisions made yet, but likely to take much from
present political structures; bi-cameral, multi-role governance
Stakeholders hold final sayreferendum mechanism built-in
Polkadot’s Relay-chain ensures that transactions between the constituent parachains get delivered and that they are all operating correctly.
Parachains can take any form of globally-coherent consensus system; potentially even another relay-chain. Enterprise-friendly encrypted, private, proof-of-authority chains are supported.
Bridges can exist to ferry transactions between the relay chain and existing, independent chains like Ethereum.
Extensible, Scalable and Flexible
Who maintains it?
Validators/nominatorsverify and finalise parachain candidates into blocks
Collatorsgather parachain transactions into PoV candidates
Fishermenmonitor the network for misbehaviour
Polkadot’s mechanics work by incentivising three kinds of activity.
Collators work independently on each parachain collecting and executing transactions. They provide blocks of transactions to validators.
Validators route transactions between parachains. They take turns vetting blocks supplied by collators and finally sign off to commit one to finality.
Fishermen receive a reward for reporting misbehaving validators.
Validators, Collators and Fishermen
Why do they bother?
Validators/nominatorsrewarded via staking-token expansion
Collatorsparachain-specific transaction fees
Fishermengifted proportion of the bond of identified culprit
Forming Consensus
Relay-chain Proof-of-stakeguarantees shared canonicality of parachains
Structured state-machinenot yet finalised; PBFT-derivative likely
Parallel validation groupsvalidators partitioned to allow scaling
Validators & Nominators
Approval votingall nominate acceptable validators, minimum reward
Constraint optimiserprovides configuration of validators/nominators for maximum lowest-bonded, minimum total inflation
Adaptive rewardsrewards alter to target % of capital bonded
Validating parachains
Collator candidatescome with proof-of-validity, external data
Availability & validityvoted on to ensure external data real
Relaying Transactions
Peer-to-peervalidators & collators self-organise to arrange delivery
of data
Tries & proofstries used to encode ingress/egress queues, allowing
compact proofs of misbehaviour
Ensuring Availability
Validatorsconsensus includes giving availability guarantees
Proof-of-Collatorregistered collators can challenge data availability
Mild punishmentvalidators given slight reward reductions on complaints
Ensuring Fairness
important that collator set contains some good guys
Golden ticketrandomly selected address
Mild rewardfor validators backing blocks whose collator’s address
is close to ticket
Open parachains can be tightly integrated into Polkadot, using Polkadot’s validators to ensure their correct operation. They are the easiest and cheapest form of integration.
Closed parachains can be weakly integrated into Polkadot, giving them the freedom to manage validation internally e.g. using a set of recognised authorities.
Bridged chains can be integrated into Polkadot too. Bridges add complexity and cost to integration, but allow the chain to exercise its own means of consensus.
Polkadot network
Internal/consortium parachain
Authorities manage parachain validation, access controls &c.
Transactions andinter-chain consensus
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