Flashblocks

Flashblocks is a rollup-boost module that enables fast confirmation times by breaking down block construction into smaller, incremental sections. This feature allows for pre-confirmations and improved user experience through faster block finalization.

Architecture

The Flashblocks setup consists of three main components:

• rollup-boost: The main service with Flashblocks enabled
• op-rbuilder: A builder with Flashblocks support
• op-reth: A fallback builder (standard EL node)

It utilizes WebSockets to stream Flashblocks from the builder to rollup-boost to minimize the latency between the Flashblocks and the sequencer.

Flashblocks Workflow

flowchart LR
    subgraph Sequencer
        ON[OP Node]
        RB[Rollup Boost]
        FEL[Fallback EL]
        BB[Block Builder]
    end
    
    subgraph Network
        WSP[WebSocket Proxy]
    end
    
    subgraph Clients
        RPC[RPC Providers]
        Users[End Users]
    end
    
    ON --> RB
    RB --> FEL
    RB <--> BB
    RB --> WSP
    WSP --> RPC
    RPC --> Users

1. WebSocket Communication: Flashblocks utilizes WebSockets to stream Flashblocks from the builder to rollup-boost once it's constructed to minimize the latency between the Flashblocks and the sequencer.
2. WebSocket Proxy: rollup-boost caches these Flashblocks and streams them to a WebSocket proxy. The proxy then fans out the Flashblocks to downstream RPC providers.
3. RPC Overlay: Once RPC providers receive these Flashblocks from the proxy, clients need to run a modified node that supports serving RPC requests with the Flashblocks preconfirmation state.
4. Full Block: At the end of the slot, the proposer requests a full block from rollup-boost. If rollup-boost does not have the Flashblocks cached due to a lost connection, it will fall back to the getPayload call to both the local execution client and the builder.

See the specs for the full design details for Flashblocks.