Finilizing the block

This document outlines the process and methodologies used to obtain the finalized block number in the Metis chain environment. It specifically addresses the retrieval methods via Layer 2 (L2) RPC and Layer 1 (L1) Smart Contract (SCC) checks, along with the operational timings for batch submissions.

Definitions

mvm_finalizedBlockNumber: The block number in the Layer 2 blockchain that has been finalized after the sequencer rotation and can no longer be reorganized when 2/3 of sequencers reach consensus.

eth_getBlockByNumber: This is the standard Ethereum JSON-RPC method used to retrieve block information, including the finalized block number.

Methodologies

Retrieving Block Numbers via L2 RPC

To obtain the latest ‘eth_getBlockByNumber’, you can query through any healthy Layer 2 RPC.

Steps to retrieve:

1. Connect to the L2 RPC.

2. Execute the ‘eth_getBlockByNumber’ method with the parameter "finalized“, similar to how you would use “latest”. This instructs the RPC to return the latest finalized block.

Example JSON-RPC request:

{
    "jsonrpc":"2.0",
    "method":"eth_getBlockByNumber",
    "params":[
        "finalized", 
        false
    ],
    "id":1
}

3. Ensure your RPC client handles updates dynamically to reflect changes post-sequencer rotations.