Reading Flashblocks Data over Ethereum JSON RPC

The Flashblocks RPC implementation provides preconfirmation data through modified Ethereum JSON-RPC endpoints using the pending tag. This allows applications to access transaction and state information from Flashblocks before they are finalized on the blockchain.

To run a node capable of serving Flashblocks, consider using https://github.com/base/node-reth/ or https://github.com/paradigmxyz/reth implementations.

At the time of writing base version has more advanced flashblocks support, including flashblocks sync over multiple blocks in case canonical head is lagging.

Data Flow

The Flashblocks RPC implementation follows this data flow:

1. WebSocket Connection: Establishes connection to rollup-boost Flashblocks endpoint
2. Payload Reception: Receives FlashblocksPayloadV1 messages containing transaction batches
3. Cache Processing: Updates in-memory cache with new transaction and state data
4. RPC Queries: Responds to client requests using cached pending data
5. State Management: Maintains consistency between confirmed and pending states

Flashblocks Payload Structure

Flashblocks payloads contain the following information:

pub struct FlashblocksPayloadV1 {
    pub version: PayloadVersion,
    pub execution_payload: OpExecutionPayloadEnvelope,
    pub metadata: Metadata,
}

pub struct Metadata {
    pub receipts: HashMap<String, OpReceipt>,
    pub new_account_balances: HashMap<String, String>,
    pub block_number: u64,
}