RPC

Specification of the rollup node RPC interface, including the optimism_outputAtBlock method for retrieving L2 output roots.

L2 Output RPC method

The Rollup node has its own RPC method, optimism_outputAtBlock which returns a 32 byte hash corresponding to the L2 output root.

Structures

These define the types used by rollup node API methods. The types defined here are extended from the engine API specs.

BlockID

• hash: DATA, 32 Bytes
• number: QUANTITY, 64 Bits

L1BlockRef

• hash: DATA, 32 Bytes
• number: QUANTITY, 64 Bits
• parentHash: DATA, 32 Bytes
• timestamp: QUANTITY, 64 Bits

L2BlockRef

• hash: DATA, 32 Bytes
• number: QUANTITY, 64 Bits
• parentHash: DATA, 32 Bytes
• timestamp: QUANTITY, 64 Bits
• l1origin: BlockID
• sequenceNumber: QUANTITY, 64 Bits - distance to first block of epoch

SyncStatus

Represents a snapshot of the rollup driver.

• current_l1: Object - instance of L1BlockRef.
• current_l1_finalized: Object - instance of L1BlockRef.
• head_l1: Object - instance of L1BlockRef.
• safe_l1: Object - instance of L1BlockRef.
• finalized_l1: Object - instance of L1BlockRef.
• unsafe_l2: Object - instance of L2BlockRef.
• safe_l2: Object - instance of L2BlockRef.
• finalized_l2: Object - instance of L2BlockRef.
• pending_safe_l2: Object - instance of L2BlockRef.
• queued_unsafe_l2: Object - instance of L2BlockRef.

Output Method API

The input and return types here are as defined by the engine API specs.

optimism_outputAtBlock

Returns an output root and associated metadata for a given L2 block.

Parameters

Name	Type	Description
blockNumber	QUANTITY, 64 bits	L2 integer block number

Returns

Name	Type	Description
version	DATA, 32 Bytes	Output root version number, beginning with 0
outputRoot	DATA, 32 Bytes	The output root
blockRef	Object	Instance of L2BlockRef
withdrawalStorageRoot	DATA, 32 Bytes	Storage root of the L2ToL1MessagePasser contract
stateRoot	DATA, 32 Bytes	The state root
syncStatus	Object	Instance of SyncStatus