OP Supervisor
Interop is currently in active development and not yet ready for production use. The information provided here may change. Check back regularly for the most up-to-date information.
OP Supervisor is a service that verifies cross-chain messages and manages interoperability between chains in the OP Stack. It serves as a hub where each op-node can index the data needed for cross-chain verification. Chain operators and teams running full nodes like RPC providers are expected to run this service.
Some features and benefits include:
- Enables secure cross-chain message passing on the Superchain
- Provides a unified point for managing interoperability data
- Supports multiple networks simultaneously
- Offers potential for public endpoints to aid in node synchronization
How cross-chain message verification works
OP Supervisor verifies messages between different chains in the OP Stack, reducing the risk of invalid or malicious cross-chain interactions.ā It centralizes the verification process, which reduces the complexity of operating individual nodesā .ā
op-geth: queriesop-supervisorduring block-building to verify if a message is sufficiently safe to include. This process involves checking each executing message and potentially undoing transactions if conflicts or unknown states are encountered.op-node: queries cross-chain safety information and coordinates safety updates between OP stack nodes andop-supervisor. It uses the API provided byop-supervisorto perform actions like:- Updating and retrieving various safety levels
- Checking and returning the
cross-unsafehead for a given chain - Attempting to promote a block to
cross-safestatus - Attempting to finalize an L2 block based on L1 finality
Log data indexing and management
OP Supervisor acts as a hub for indexing data that every op-node needs to cross-verify with other chains, centralizing the process of managing interoperability data. Maintains the integrity of cross-chain interactions by tracking safety changesā across the Superchain, ensuring consistent application of invalid dependency resolutions. ā
op-supervisor indexes two types of cross-chain dependencies:
- Interop messages (events):
op-supervisormaintains an events-index per L2 chain, which determines message-dependencies to check if blocks are safe - L1 DA (data availability):
op-supervisortracks the L1 DA for L2 blocks and maintains a DA safety-index per L2 chain, which helps determine how to rewind L2 chains to resolve invalid dependencies
API for cross-chain safety
OP Supervisor provides an interface for op-node to query cross-chain safety information and coordinate safety updates between OP stack nodes and op-supervisorā ā . OP-Supervisor uses a global read API to determine message safety and block safety, utilizing both the events index and the safety index (See op-supervisor's log data indexing). The API is designed to handle potential L1 reorgs that can affect the validity of cross-chain messagesā .
Key API methods include:
| Method | Description |
|---|---|
UnsafeView and SafeView | Returns 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 | Tells 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 |
For a full listing of API names, see the op-supervisor client (opens in a new tab).
RPC access to all chains
OP Supervisor requires RPC access to all chains in the dependency set. This allows op-supervisor to verify cross-chain messages and sync data across multiple networks simultaneously, such as OP Mainnet and Base nodes using the same instance.
Benefits:
- Scalability: As the number of chains in the Superchain grows,
op-supervisorcan handle the increasing complexity of cross-chain interactions. - Improved reliability: It enables a more redundant setup, which is good for stability in the growing ecosystem.
Next steps
- Want to learn more? Read our guide on the anatomy of a cross-chain message or check out this interop design video walk-thru (opens in a new tab).
- For more info about how OP Stack interoperability works under the hood, check out the specs (opens in a new tab).