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OP Node

The OP node was upgraded to support the new based architecture and process Frags.

The main changes include:

  • a new capability in the P2P server, to support the new messages
  • a new based_ RPC namespace, used by the local gateway to make the initial push of p2p messages
  • an extended EngineAPI to enable processing of Frag in the execution layer after signature verification

Importantly, all these changes are incremental and backwards compatible. Non-modified nodes will still be able to stay in the network and receive new blocks, they just won't be able to process Frags and provide preconfirmations.

The forked repo with changes can be found in based-optimism.

op-node

P2P Capability​

The P2P server is extended to include a new capability to broadcast messages to other OP nodes of the network. The current implementation simply extends the existing libp2p protocol already used by nodes, while in the future we plan to move to a new faster leader-aware gossip.

RPC​

To avoid re-implementing the full p2p in the gateway, a new based_ namespace is introduced, used by the gateway to make the initial push of p2p messages, which will then be broacast to the rest of the network.

based_env​

Parameters​

  • signature: The signature of the gateway.
  • message: The EnvV0 message.

Returns​

  • OK if the frag was successfully received and published.
  • ERROR if the frag was not successfully received/published.

Example​

{
    "id": 1,
    "jsonrpc": "2.0",
    "method": "based_env",
    "params": [{
        "message": {
            "basefee": 4,
            "beneficiary": "0x1234567890123456789012345678901234567890",
            "difficulty": "0x5",
            "extraData": "0x010203",
            "gasLimit": 3,
            "number": 1,
            "parentBeaconBlockRoot": "0xe75fae0065403d4091f3d6549c4219db69c96d9de761cfc75fe9792b6166c758",
            "parentHash": "0xe75fae0065403d4091f3d6549c4219db69c96d9de761cfc75fe9792b6166c758",
            "prevrandao": "0xe75fae0065403d4091f3d6549c4219db69c96d9de761cfc75fe9792b6166c758",
            "timestamp": 2
        }],
        "signature": "0x4fc733cc2f0b680e15452db40b9453412ccb25507582b192c1ea4fc4deaf709845002ab44af42327ed4b8b12943412810a8d9984ea1609dfc6f77338f8c395b41c"
    }
}

based_newFrag​

Parameters​

  • signature: The signature of the gateway.
  • message: The FragV0 message.

Returns​

  • OK if the frag was successfully received and published.
  • ERROR if the frag was not successfully received/published.

Example​

{
    "id": 1,
    "jsonrpc": "2.0",
    "method": "based_newFrag",
    "params": [{
        "message": {
            "blockNumber": 1,
            "isLast": true,
            "seq": 0,
            "txs": [
                "0x010203"
            ]
        }],
        "signature": "0xa47da12abd5563f45332e637d1de946c3576902a245511d86826743c8af1f1e2093d4f5efd5b9630c0acc5f2bb23f236b4f7bdbe0d21d281b2bd2ff60c6cf1861b"
    }
}

based_sealFrag​

Parameters​

  • signature: The signature of the gateway.
  • message: The SealV0 message.

Returns​

  • OK if the frag was successfully received and published.
  • ERROR if the frag was not successfully received/published.

Example​

{
    "id": 1,
    "jsonrpc": "2.0",
    "method": "based_sealFrag",
    "params": [{
        "message": {
            "blockHash": "0xe75fae0065403d4091f3d6549c4219db69c96d9de761cfc75fe9792b6166c758",
            "blockNumber": 123,
            "gasLimit": 1000000,
            "gasUsed": 25000,
            "parentHash": "0xe75fae0065403d4091f3d6549c4219db69c96d9de761cfc75fe9792b6166c758",
            "receiptsRoot": "0xe75fae0065403d4091f3d6549c4219db69c96d9de761cfc75fe9792b6166c758",
            "stateRoot": "0xe75fae0065403d4091f3d6549c4219db69c96d9de761cfc75fe9792b6166c758",
            "totalFrags": 8,
            "transactionsRoot": "0xe75fae0065403d4091f3d6549c4219db69c96d9de761cfc75fe9792b6166c758"
        }],
        "signature": "0x090f69ccf02e0f468cac96f71bbf4b7732c63f3d50a4881f8665c1718570928e4497706eac2fe7da8b47ce355482ada8763614a3575a1af066ad06320b707c531b"
    }
}

Engine API Upgrade​

New methods in the based_ namespace are added to enable the OP node to send the Frags payloads to the execution layer (EL). Messages are only sent after singature verification of the gateway identity. The new methods are:

  • engine_newFragV0
  • engine_sealFragV0
  • engine_envV0

The processing is detailed in the next section.