# 6. Job Declaration Protocol
As outlined above, this protocol runs between the Job Declarator and Pool and can be provided as a trusted 3rd party service for mining farms.
Protocol flow:
Figure 5.a Job Declaration Protocol: Flow
# 6.1 Job Declaration Protocol Messages
# 6.1.1 SetupConnection Flags for Job Declaration Protocol
Flags usable in SetupConnection.flags and SetupConnection.Error::flags:
| Field Name | Bit | Description |
|---|---|---|
| REQUIRES_ASYNC_JOB_MINING | 0 | The Job Declarator requires that the mining_job_token in AllocateMiningJobToken.Success can be used immediately on a mining connection in SetCustomMiningJob message, even before DeclareMiningJob and DeclareMiningJob.Success messages have been sent and received. The server MUST only send AllocateMiningJobToken.Success messages with async_mining_allowed set. |
No flags are yet defined for use in SetupConnection.Success.
# 6.1.2 AllocateMiningJobToken (Client -> Server)
A request to get an identifier for a future-submitted mining job.
Rate limited to a rather slow rate and only available on connections where this has been negotiated. Otherwise, only mining_job_token(s) from AllocateMiningJobToken.Success are valid.
| Field Name | Data Type | Description |
|---|---|---|
| user_identifier | STR0_255 | Unconstrained sequence of bytes. Whatever is needed by the pool to identify/authenticate the client, e.g. "braiinstest". Additional restrictions can be imposed by the pool. It is highly recommended that UTF-8 encoding is used. |
| request_id | U32 | Unique identifier for pairing the response |
# 6.1.3 AllocateMiningJobToken.Success (Server -> Client)
The Server MUST NOT change the value of coinbase_output_max_additional_size in AllocateMiningJobToken.Success messages unless required for changes to the pool’s configuration.
Notably, if the pool intends to change the space it requires for coinbase transaction outputs regularly, it should simply prefer to use the maximum of all such output sizes as the coinbase_output_max_additional_size value.
| Field Name | Data Type | Description |
|---|---|---|
| request_id | U32 | Unique identifier for pairing the response |
| mining_job_token | B0_255 | Token that makes the client eligible for committing a mining job for approval/transaction declaration or for identifying custom mining job on mining connection. |
| coinbase_output_max_additional_size | U32 | The maximum additional serialized bytes which the pool will add in coinbase transaction outputs. See discussion in the Template Distribution Protocol's CoinbaseOutputDataSize message for more details. |
| async_mining_allowed | BOOL | If true, the mining_job_token can be used immediately on a mining connection in the SetCustomMiningJob message, even before DeclareMiningJob and DeclareMiningJob.Success messages have been sent and received. If false, Job Declarator MUST use this token for DeclareMiningJob only. This MUST be true when SetupConnection.flags had REQUIRES_ASYNC_JOB_MINING set. |
| coinbase_tx_outputs | B0_64K | Bitcoin transaction outputs added by the pool |
# 6.1.4 DeclareMiningJob (Client -> Server)
A request sent by the Job Declarator that proposes a selected set of transactions to the upstream (pool) node.
| Field Name | Data Type | Description |
|---|---|---|
| request_id | U32 | Unique identifier for pairing the response |
| mining_job_token | B0_255 | Previously reserved mining job token received by AllocateMiningJobToken.Success |
| version | U32 | Version header field. To be later modified by BIP320-consistent changes. |
| coinbase_tx_prefix | B0_64K | The coinbase transaction nVersion field |
| coinbase_tx_suffix | B0_64K | Up to 8 bytes (not including the length byte) which are to be placed at the beginning of the coinbase field in the coinbase transaction |
| tx_short_hash_nonce | U64 | A unique nonce used to ensure tx_short_hash collisions are uncorrelated across the network |
| tx_short_hash_list | SEQ0_64K[SHORT_TX_ID] | Sequence of SHORT_TX_IDs. Inputs to the SipHash functions are transaction hashes from the mempool. Secret keys k0, k1 are derived from the first two little-endian 64-bit integers from the SHA256(tx_short_hash_nonce), respectively (see bip-0152 for more information). Upstream node checks the list against its mempool. Does not include the coinbase transaction (as there is no corresponding full data for it yet). |
| tx_hash_list_hash | U256 | Hash of the full sequence of SHA256(transaction_data) contained in the transaction_hash_list |
| excess_data | B0_64K | Extra data which the Pool may require to validate the work (as defined in the Template Distribution Protocol) |
# 6.1.5 DeclareMiningJob.Success (Server -> Client)
| Field Name | Data Type | Description |
|---|---|---|
| request_id | U32 | Identifier of the original request |
| new_mining_job_token | B0_255 | Unique identifier provided by the pool of the job that the Job Declarator has declared with the pool. It MAY be the same token as DeclareMiningJob::mining_job_token if the pool allows to start mining on not yet declared job. If the token is different from the one in the corresponding DeclareMiningJob message (irrespective of if the client is already mining using the original token), the client MUST send a SetCustomMiningJob message on each Mining Protocol client which wishes to mine using the declared job. |
# 6.1.6 DeclareMiningJob.Error (Server->Client)
| Field Name | Data Type | Description |
|---|---|---|
| request_id | U32 | Identifier of the original request |
| error_code | STR0_255 | |
| error_details | B0_64K | Optional data providing further details to given error |
Possible error codes:
invalid-mining-job-tokeninvalid-job-param-value-{}-{}is replaced by a particular field name fromDeclareMiningJobmessage
# 6.1.7 IdentifyTransactions (Server->Client)
Sent by the Server in response to a DeclareMiningJob message indicating it detected a collision in the tx_short_hash_list, or was unable to reconstruct the tx_hash_list_hash.
| Field Name | Data Type | Description |
|---|---|---|
| request_id | U32 | Unique identifier for the pairing response to the DeclareMiningJob message |
# 6.1.8 IdentifyTransactions.Success (Client->Server)
Sent by the Client in response to an IdentifyTransactions message to provide the full set of transaction data hashes.
| Field Name | Data Type | Description |
|---|---|---|
| request_id | U32 | Unique identifier for the pairing response to the DeclareMiningJob/IdentifyTransactions message |
| tx_data_hashes | SEQ0_64K[U256] | The full list of transaction data hashes used to build the mining job in the corresponding DeclareMiningJob message |
# 6.1.9 ProvideMissingTransactions (Server->Client)
| Field Name | Data Type | Description |
|---|---|---|
| request_id | U32 | Identifier of the original AllocateMiningJobToken request |
| unknown_tx_position_list | SEQ0_64K[U16] | A list of unrecognized transactions that need to be supplied by the Job Declarator in full. They are specified by their position in the original DeclareMiningJob message, 0-indexed not including the coinbase transaction transaction. |
# 6.1.10 ProvideMissingTransactions.Success (Client->Server)
This is a message to push transactions that the server did not recognize and requested them to be supplied in ProvideMissingTransactions.
| Field Name | Data Type | Description |
|---|---|---|
| request_id | U32 | Identifier of the original AllocateMiningJobToken request "" |
| transaction_list | SEQ0_64K[B0_16M] | List of full transactions as requested by ProvideMissingTransactions, in the order they were requested in ProvideMissingTransactions |
# 6.1.11 SubmitSolution (Client -> Server)
| Field Name | Data Type | Description |
|---|---|---|
| extranonce | B0_32 | Extranonce bytes which need to be added to coinbase to form a fully valid submission. (This is the full extranonce) |
| prev hash | U256 | Hash of the last block |
| nonce | U32 | Nonce leading to the hash being submitted |
| ntime | U32 | The nTime field in the block header. |
| nbits | U32 | Block header field |