Superchain interop is in active development. Some features may be experimental.
- Log entries, which could be initiating messages for cross-domain messages.
- Blockchain heads, which are the latest blocks at various levels of confidence and safety:
- Unsafe (the latest block available through the gossip protocol)
- Local-safe (the latest block written to L1)
- Cross-safe (the latest block written to L1, and for which all the dependencies are written to L1)
- Finalized (the latest block written to L1, and that L1 block is safe from reorgs)
How other components use OP-Supervisor
-
The execution client (typically
op-geth
) queriesop-supervisor
during block-building to verify if a message is sufficiently safe to include. To do this, the execution client looks at every executing message and queriesop-supervisor
to see if there is a corresponding initiating message. -
op-node
queries cross-chain safety information and coordinates safety updates between OP stack nodes andop-supervisor
. It uses the API provided byop-supervisor
to:- Retrieve the unsafe, local-safe, cross-safe, and finalized heads for other chains.
- Update the unsafe, local-safe, and finalized heads for its own chain.
- Attempt to promote blocks in its own chain to cross-safe status.
- Attempt to finalize L2 blocks based on L1 finality.
API
Here are the most important API methods exposed by OP-Supervisor. For a full listing of API names, see the source code.Method(s) | Description |
---|---|
UnsafeView and SafeView | Return the Local and Cross heads for their respective levels |
DerivedFrom | OP Nodes use to check the L1 source of the Supervisor (needed for Safe Head tracking) |
UpdateLocalSafe and UpdateLocalUnsafe | Tell the Supervisor when the Node’s heads change |
Finalized | Returns the Finalized Head |
UpdateFinalizedL1 | Signals to the Supervisor new finality signals |
CheckMessage | Checks logs in the DB directly in tests |
Next steps
- Build a revolutionary app that uses multiple blockchains within the Superchain
- Deploy a SuperchainERC20 to the Superchain
- Learn how ETH can move across chains
- For more info about how Superchain interoperability works under the hood, check out the specs.