Disperser API

Table of Contents

• Service

  • Disperser

• Data Structure

  • BatchHeader

  • BatchMetadata

  • BlobHeader

  • BlobInfo

  • BlobQuorumParam

  • BlobStatusReply

  • BlobStatusRequest

  • BlobVerificationProof

  • DisperseBlobReply

  • DisperseBlobRequest

  • RetrieveBlobRequest

  • RetrieveBlobReply

  • SecurityParams

  • BlobStatus

• Scalar Value Types

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Service

Disperser

Disperser defines the public APIs for dispersing blobs.

Method Name	Request Type	Response Type	Description
DisperseBlob	DisperseBlobRequest	DisperseBlobReply	This API accepts blob to disperse from clients. This executes the dispersal async, i.e. it returns once the request is accepted. The client could use GetBlobStatus() API to poll the the processing status of the blob.
GetBlobStatus	BlobStatusRequest	BlobStatusReply	This API is meant to be polled for the blob status.
RetrieveBlob	RetrieveBlobRequest	RetrieveBlobReply	This retrieves the requested blob from the Disperser's backend. This is a more efficient way to retrieve blobs than directly retrieving from the DA Nodes (see detail about this approach in api/proto/retriever/retriever.proto). The blob should have been initially dispersed via this Disperser service for this API to work.

Data Structure

BatchHeader

Field	Type	Label	Description
batch_root	bytes		The root of the merkle tree with the hashes of blob headers as leaves.
quorum_numbers	bytes		All quorums associated with blobs in this batch.
quorum_signed_percentages	bytes		The percentage of stake that has signed for this batch. The quorum_signed_percentages[i] is percentage for the quorum_numbers[i].
reference_block_number	uint32		The Ethereum block number at which the batch was created. The Disperser will encode and disperse the blobs based on the onchain info (e.g. operator stakes) at this block number.

BatchMetadata

Field	Type	Label	Description
batch_header	BatchHeader
signatory_record_hash	bytes		The hash of all public keys of the operators that did not sign the batch.
fee	bytes		The gas fee of confirming this batch. It's the bytes representation of a big.Int value.
confirmation_block_number	uint32		The Ethereum block number at which the batch is confirmed onchain.
batch_header_hash	bytes		This is the hash of the ReducedBatchHeader defined onchain, see: https://github.com/0glabs/0g-data-avail/blob/master/contracts/src/interfaces/IZGDAServiceManager.sol#L43 The is the message that the operators will sign their signatures on.

BlobHeader

Field	Type	Label	Description
commitment	bytes		KZG commitment to the blob.
data_length	uint32		The length of the blob in symbols (each symbol is 31 bytes).
blob_quorum_params	BlobQuorumParam	repeated	The params of the quorums that this blob participates in.

BlobInfo

BlobInfo contains information needed to confirm the blob against the 0G DA contracts

Field	Type	Label	Description
blob_header	BlobHeader
blob_verification_proof	BlobVerificationProof

BlobQuorumParam

Field	Type	Label	Description
quorum_number	uint32		The ID of the quorum.
adversary_threshold_percentage	uint32		Same as SecurityParams.adversary_threshold.
quorum_threshold_percentage	uint32		Same as SecurityParams.quorum_threshold.
quantization_param	uint32		This determines the nominal number of chunks for the blob, which is nominal_num_chunks = quantization_param * num_operators. A chunk is the smallest unit that's distributed to DA Nodes, corresponding to a set of evaluations of the polynomial (representing the blob) and a KZG multiproof.
encoded_length	uint64		The length of the blob after encoding (in number of symbols).

BlobStatusReply

Field	Type	Label	Description
status	BlobStatus		The status of the blob.
info	BlobInfo		The blob info needed for clients to confirm the blob against the 0G DA contracts.

BlobStatusRequest

BlobStatusRequest is used to query the status of a blob.

Field	Type	Label	Description
request_id	bytes

BlobVerificationProof

Field	Type	Label	Description
batch_id	uint32		batch_id is an incremental ID assigned to a batch by ZGDAServiceManager
blob_index	uint32		The index of the blob in the batch (which is logically an ordered list of blobs).
batch_metadata	BatchMetadata
inclusion_proof	bytes		inclusion_proof is a merkle proof for a blob header's inclusion in a batch
quorum_indexes	bytes		indexes of quorums in BatchHeader.quorum_numbers that match the quorums in BlobHeader.blob_quorum_params Ex. BlobHeader.blob_quorum_params = [ { quorum_number = 0, ... }, { quorum_number = 3, ... }, { quorum_number = 5, ... }, ] BatchHeader.quorum_numbers = [0, 5, 3] => 0x000503 Then, quorum_indexes = [0, 2, 1] => 0x000201

DisperseBlobReply

Field	Type	Label	Description
result	BlobStatus		The status of the blob associated with the request_id.
request_id	bytes		The request ID generated by the disperser. Once a request is accepted (although not processed), a unique request ID will be generated. Two different DisperseBlobRequests (determined by the hash of the DisperseBlobRequest) will have different IDs, and the same DisperseBlobRequest sent repeatedly at different times will also have different IDs. The client should use this ID to query the processing status of the request (via the GetBlobStatus API).

DisperseBlobRequest

Field	Type	Label	Description
data	bytes		The data to be dispersed. The size of data must be <= 512KiB.
security_params	SecurityParams	repeated	Security parameters allowing clients to customize the safety (via adversary threshold) and liveness (via quorum threshold). Clients can define one SecurityParams per quorum, and specify multiple quorums. The disperser will ensure that the encoded blobs for each quorum are all processed within the same batch.

RetrieveBlobRequest

RetrieveBlobRequest contains parameters to retrieve the blob.

Field	Type	Label	Description
batch_header_hash	bytes
blob_index	uint32

RetrieveBlobReply

RetrieveBlobReply contains the retrieved blob data

Field	Type	Label	Description
data	bytes

SecurityParams

SecurityParams contains the security parameters for a given quorum.

Field	Type	Label	Description
quorum_id	uint32		The ID of the quorum. The quorum must be already registered on EigenLayer. The ID must be in range [0, 255].
adversary_threshold	uint32		The max percentage of stake within the quorum that can be held by or delegated to adversarial operators.

BlobStatus

Name	Number	Description
UNKNOWN	0
PROCESSING	1	PROCESSING means that the blob is currently being processed by the disperser
CONFIRMED	2	CONFIRMED means that the blob has been dispersed to DA Nodes and the dispersed batch containing the blob has been confirmed onchain
FAILED	3	FAILED means that the blob has failed permanently (for reasons other than insufficient signatures, which is a separate state)
FINALIZED	4	FINALIZED means that the block containing the blob's confirmation transaction has been finalized on Ethereum
INSUFFICIENT_SIGNATURES	5	INSUFFICIENT_SIGNATURES means that the quorum threshold for the blob was not met for at least one quorum.

Scalar Value Types

.proto Type	Notes	C++	Java	Python	Go	C#	PHP	Ruby
double		double	double	float	float64	double	float	Float
float		float	float	float	float32	float	float	Float
int32	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint32 instead.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
int64	Uses variable-length encoding. Inefficient for encoding negative numbers – if your field is likely to have negative values, use sint64 instead.	int64	long	int/long	int64	long	integer/string	Bignum
uint32	Uses variable-length encoding.	uint32	int	int/long	uint32	uint	integer	Bignum or Fixnum (as required)
uint64	Uses variable-length encoding.	uint64	long	int/long	uint64	ulong	integer/string	Bignum or Fixnum (as required)
sint32	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int32s.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
sint64	Uses variable-length encoding. Signed int value. These more efficiently encode negative numbers than regular int64s.	int64	long	int/long	int64	long	integer/string	Bignum
fixed32	Always four bytes. More efficient than uint32 if values are often greater than 2^28.	uint32	int	int	uint32	uint	integer	Bignum or Fixnum (as required)
fixed64	Always eight bytes. More efficient than uint64 if values are often greater than 2^56.	uint64	long	int/long	uint64	ulong	integer/string	Bignum
sfixed32	Always four bytes.	int32	int	int	int32	int	integer	Bignum or Fixnum (as required)
sfixed64	Always eight bytes.	int64	long	int/long	int64	long	integer/string	Bignum
bool		bool	boolean	boolean	bool	bool	boolean	TrueClass/FalseClass
string	A string must always contain UTF-8 encoded or 7-bit ASCII text.	string	String	str/unicode	string	string	string	String (UTF-8)
bytes	May contain any arbitrary sequence of bytes.	string	ByteString	str	[]byte	ByteString	string	String (ASCII-8BIT)