Supervisor

Table of Contents

Overview
RPC API
- Common types
- Methods

Overview

The supervisor is an implementation detail of OP Stack native interop and is not the only architecture that can be used to implement it. The supervisor is responsible for indexing data from all of the chains in a cluster so that the safety level of executing messages can quickly be determined.

RPC API

Common types

`Identifier`

The identifier of a message. Corresponds to an Identifier.

Object:

origin: Address
blockNumber: HexUint64
logIndex: HexUint64
timestamp: HexUint64
chainID: ChainID

`Message`

Describes an initiating message.

Object:

identifier: Identifier - identifier of the message
payloadHash: Hash - keccak256 hash of the message-payload bytes

`ExecutingDescriptor`

Describes the context for message verification. Specifically, this helps apply message-expiry rules on message checks.

Object:

timestamp: HexUint64

`HexUint64`

STRING: Hex-encoded big-endian number, variable length up to 64 bits, prefixed with 0x.

`Int`

NUMBER: Regular JSON number, always integer. Assumed to always fit in 51 bits.

`ChainID`

STRING: Hex-encoded big-endian number, variable length up to 256 bits, prefixed with 0x.

`Hash`

STRING: Hex-encoded, fixed-length, representing 32 bytes, prefixed with 0x.

`Bytes`

STRING: Hex-encoded, variable length (always full bytes, no odd number of nibbles), representing a bytes list, prefixed with 0x.

`BlockID`

Describes a block.

OBJECT:

hash: HASH - block hash
number: Int - block number

`BlockRef`

Describes a block.

OBJECT:

hash: Hash - block hash
number: Int - block number
parentHash: Hash - block parent-hash
timestamp: Int - block timestamp

`DerivedIDPair`

`ChainRootInfo`

OBJECT:

chainId: HexUint64 - The chain ID (Note: this is changing to ChainID soon)
canonical: Hash - output root at the latest canonical block
pending: Bytes - output root preimage

`SuperRootResponse`

OBJECT:

crossSafeDerivedFrom: BlockID - common derived-from where all chains are cross-safe
timestamp: Int - The timestamp of the super root
superRoot: Hash - The root of the super root
version: Int - The version of the response
chains: ARRAY of ChainRootInfo - List of chains included in the super root

`SafetyLevel`

The safety level of the message. Corresponds to a verifier SafetyLevel.

STRING, one of:

invalid
unsafe
cross-unsafe
local-safe
safe
finalized

Methods

`supervisor_checkMessage`

Checks the safety level of a specific message based on its identifier and message hash. This RPC is useful for the block builder to determine if a message should be included in a block.

Parameters: