Watchtower Architecture
Software Architecture - client, APIs and contracts
Last updated
Software Architecture - client, APIs and contracts
Last updated
WitnessChain Watchtowers' software stack comprise of
Watchtower Client (written in Go)
On-chain Smart Contracts on Ethereum & on a Layer-2 chain
Layer 1: Operator Registry, Settlement (ServiceManager aka EigenTower) & Alert Manager
Layer 2: DiligenceProofManager Contract
Centralized Aggregator (to submit "batched" bounty settlements (rewards) on Ethereum)
At a high level, the process of L2 state validation in a watchtower node client has 4 stages
Output State Root Extraction from L1
Output State Root Extraction (Tracer execution) from L2 Node
Comparison & generating proofs of diligence
Smart Contract integration to publish the proofs
This is Registry-type contract for keeping track of operators. It is used for registering and deregistering new operators. Only registered and delegated EigenLayer operators are allowed into the watchtower network
Adds the list of operators to the whitelist mapping
Removes the operator from the whitelist mapping
Registers the operator as a watchtower
Deregisters the watchtower
The watchtower client will no longer be able to post any proofs, until the operator registers the watchtower address again
The DiligenceProofManager Contract contains functionality for miners (aka Watchtowers) to submit (mine) their Proofs of Diligence for a Bounty Period (which is the period between 2 L2 Txn Batch submissions). After the next L2 output state root is posted on L1, the bounty is rewarded to the miner. Bounties are given for every L2 Output (L2 Block).
The owner of the Contract sets the Bounty Amount.
Consider PoD bounties are just reward points for now. Lets say 1 point for every L2 block mined successfully by a WatchTower. A detailed Points documentation is in progress.
The owner of the Contract sets the Bounty Amount.
Consider PoI bounties are just reward points for now. Lets say 1 point for every L2 block mined successfully by a WatchTower. A detailed Points documentation is in progress.
Watchtower(s) submits/mine a L2 block by submitting the Hash(intermediate state root) and signing the Hash.
Validations on Contract take care if the right sender is sending this transaction
Watchtower(s) submits/mine a L2 block for a PoI proof.
Validations on Contract take care if the right sender is sending this transaction
This contract is used for keeping track of alerts raised by watchtowers
Raise an alert when there is a mismatch in output root between what is exeucte on L2 Node and asserted on L1 Contract
Get all alerts raised so far a particular chainID and L2BlockNumber
The WitnessHub Contract enables the aggregator to process settlements for collective submissions of Proofs of Diligence and Proofs of Inclusion provided by watchtowers on a Layer 2 (L2) blockchain. These submissions correspond to a Bounty Period, which is defined as the interval between two transactions on the L2 chain.
Accepts a list of operators and proof rewards, which correspond to the aggregated rewards for the operators across their watchtowers's proof submissions for a particular chain id and a range of blocks. This function may only be called by the aggregator.
An aggregator, a centralised entity managed by Witness Chain, listens for the PoD and PoI submissions made by the watchtowers on the L2 chain contracts (DiligenceProofManager). It employs a "weighted stake" strategy to determine the winning watchtower for each group of blocks.
This approach allows for a fair and transparent winning process. The winning watchtower's information, along with the number of wins and a Proof of Settlement, is then recorded on the WitnessHub settlement contract on Layer 1 (L1).
The aggregator has the flexibility to adjust the settlement frequency based on gas costs, optimizing the balance between operational efficiency and cost-effectiveness.
Called By
WatchTower (EigenLayer Node Operator)
Returns
None
Emits
NewBountyClaimed event
Called By
WatchTower (EigenLayer Node Operator)
Returns
None
Emits
NewBountyClaimed event
Called By
Aggregator
Returns
None
Emits
NewRewardsUpdate
Called By
Contract Owner
Returns
None
Emits
Called By
Contract Owner
Returns
None
Emits
Called By
Node operator
Returns
None
Emits
Called By
Node operator
Returns
None
Emits
Called By
Owner of the Contract
Returns
None
Emits
Called By
Owner of the Contract
Returns
None
Emits
Called By
Node Operator
Returns
None
Emits
Called By
Node Operator
Returns
Emits
None