Builder API

The following describes the API endpoints a builder needs to support in order to build blocks in Espresso.

These API endpoints are actively maintained and might change going forward.

GET block_info/availableblocks/:parent_hash/:view_number/:sender/:signature:

This endpoint allows a sequencer node to query a builder for a list of available blocks that the builder can provide, ensuring consistency with the ongoing consensus defined by the specified parent_hash.

Parameters

Name	Type	Description
parent_hash	TaggedBase64	The hash of the parent block in the current consensus chain. This parameter ensures that the returned blocks are valid continuations of the existing chain.
view_number	Integer	View number in Hotshot.
sender	TaggedBase64	The address or identifier of the entity making the request (i.e., the sequencer node).
signature	TaggedBase64	A cryptographic signature generated by the sequencer node, authenticating the request and proving its authenticity

Returns

[
    { 
        "block_hash": TaggedBase64,
        "block_size": integer,
        "offered_fee": integer,
        "signature": TaggedBase64,
        "sender": TaggedBase64
    }
]

GET block_info/claimblock/:block_hash/:view_number/:sender/:signature:

Upon receiving the metadata about available blocks through the previously mentioned endpoint, the sequencer node will utilize this dedicated endpoint to retrieve the complete and comprehensive content of chosen block. This endpoint will provide the sequencer node with the entirety of the block data, including all transactions, consensus data, and any other pertinent information encapsulated within the block. By leveraging this endpoint, the sequencer node can access and process the complete block content, enabling it to perform its designated functions effectively inside the Hotshot consensus.

Parameters

Name	Type	Description
block_hash	TaggedBase64	The hash of the block provided as a response in previous API.
view_number	Integer	View number in Hotshot.
sender	TaggedBase64	The address or identifier of the entity making the request (i.e., the sequencer node).
signature	TaggedBase64	A cryptographic signature generated by the sequencer node, authenticating the request and proving its authenticity

Returns

{ 
    "block_payload": Payload,
    "metadata": MetaData,
    "signature": TaggedBase64,
    "sender": TaggedBase64
}

GET block_info/claimheaderinput/:block_hash/:view_number/:sender/:signature

This endpoint enables a sequencer node to retrieve the relevant fee information associated with a specific block, facilitating a transparent payout mechanism for the builder responsible for constructing that block.

Note: The block_hash should match the one requested in previous API i.e claim_block for consistent fee payoff.

Parameters

Name	Type	Description
block_hash	TaggedBase64	The hash of the block provided as a response in first API.
view_number	Integer	View number in Hotshot.
sender	TaggedBase64	The address or identifier of the entity making the request (i.e., the sequencer node).
signature	TaggedBase64	A cryptographic signature generated by the sequencer node, authenticating the request and proving its authenticity

Returns

{ 
    "vid_commitment": VidCommitment, 
    "vid_precompute_data": VidPrecomputeData,
    "fee_signature": TaggedBase64,
    "signature": "TaggedBase64,
    "sender" = TaggedBase64 
}

POST /txn_submit/submit

It enables external user to submit directly to builder's private transactions mempool.

• Returns the hash of the transaction if it was successfully submitted. This does not mean the transaction has yet been sequenced. The user can check for inclusion of the transaction using /availability/transaction/hash/:hash from the availability API.

  • Request Body Transaction

  • Returns tagged<TX>

POST /txn_submit/batch

It enables external user to submit a list of transactions to builder's private transactions mempool.

• Returns the corresponding list of transaction hashes if it were successfully submitted. This does not mean the transaction has yet been sequenced. The user can check for inclusion of the transaction using /availability/transaction/hash/:hash from the availability API.

  • Request Body Vec<Transaction>

  • Returns Vec<tagged<TX>>