Sequences

Deposit

Bridge ERC 20 tokens from rootchain to childchain via deposit.

sequenceDiagram
    User->>Furtheon: deposit
    Furtheon->>RootERC20.sol: approve(RootERC20Predicate)
    Furtheon->>RootERC20Predicate.sol: deposit()
    RootERC20Predicate.sol->>RootERC20Predicate.sol: mapToken()
    RootERC20Predicate.sol->>StateSender.sol: syncState(MAP_TOKEN_SIG), recv=ChildERC20Predicate
    RootERC20Predicate.sol-->>Furtheon: TokenMapped Event
    StateSender.sol-->>Furtheon: StateSynced Event to map tokens on child predicate
    RootERC20Predicate.sol->>StateSender.sol: syncState(DEPOSIT_SIG), recv=ChildERC20Predicate
    StateSender.sol-->>Furtheon: StateSynced Event to deposit on child chain
    Furtheon->>User: ok
    Furtheon->>StateReceiver.sol:commit()
    StateReceiver.sol-->>Furtheon: NewCommitment Event
    Furtheon->>StateReceiver.sol:execute()
    StateReceiver.sol->>ChildERC20Predicate.sol:onStateReceive()
    ChildERC20Predicate.sol->>ChildERC20.sol: mint()
    StateReceiver.sol-->>Furtheon:StateSyncResult Event

Withdraw

Bridge ERC 20 tokens from childchain to rootchain via withdrawal.

sequenceDiagram
    User->>Furtheon: withdraw
    Furtheon->>ChildERC20Predicate.sol: withdrawTo()
    ChildERC20Predicate.sol->>ChildERC20: burn()
    ChildERC20Predicate.sol->>L2StateSender.sol: syncState(WITHDRAW_SIG), recv=RootERC20Predicate
    Furtheon->>User: tx hash
    User->>Furtheon: get tx receipt
    Furtheon->>User: exit event id
    ChildERC20Predicate.sol-->>Furtheon: L2ERC20Withdraw Event
    L2StateSender.sol-->>Furtheon: StateSynced Event
    Furtheon->>Furtheon: Seal block
    Furtheon->>CheckpointManager.sol: submit()

Exit

Finalize withdrawal of ERC 20 tokens from childchain to rootchain.

sequenceDiagram
    User->>Furtheon: exit, event id:X
    Furtheon->>Furtheon: bridge_generateExitProof()
    Furtheon->>CheckpointManager.sol: getCheckpointBlock()
    CheckpointManager.sol->>Furtheon: blockNum
    Furtheon->>Furtheon: getExitEventsForProof(epochNum, blockNum)
    Furtheon->>Furtheon: createExitTree(exitEvents)
    Furtheon->>Furtheon: generateProof()
    Furtheon->>ExitHelper.sol: exit()
    ExitHelper.sol->>CheckpointManager.sol: getEventMembershipByBlockNumber()
    ExitHelper.sol->>RootERC20Predicate.sol:onL2StateReceive()
    RootERC20Predicate.sol->>RootERC20: transfer()
    Furtheon->>User: ok
    RootERC20Predicate.sol-->>Furtheon: ERC20Withdraw Event
    ExitHelper.sol-->>Furtheon: ExitProcessed Event