Getminingcandidate

getminingcandidate is a Remote Procedure call (RPC) program. The RPC calls are located at an SV node and are currently managed by Maestro software, though a number of software packages may perform these tasks.

getminingcandidate returns a mining candidate or candidate block to the node which originally requested it. The node requests a block to mine. getminingcandidate is the program that obtains the block to mine.

The getminingcandidate program or call is a replacement for getblocktemplate program. The replacement requirement arose from the need to process bigger blocks with Merkle tree paths in the block header. The Merkle tree proof in the block header allows for confirmation of transactions rather than reading the transactions as a whole. Consequently there can be more transactions within a block and more efficient external processing of the block.

The miner can make a request with either of the above programs for block information: The getblocktemplate returns a full block. The getminingcandidate program returns the blockheader only for the mining candidate. The returned data is the block candidate data. It is expressed in the JSON language for data processing.

Parameter table for the block header

Parameter	Description
Id	Candidate identifier for submitminingsolution
Prevhash	Hash of the previous block (hex string)
Coinbase	Coinbase transaction (optional hex string encoded binary transaction)
Version	Block version
nBits	Difficulty given as hex string.
Time	Block time.
Height	Current block height
merkleProof	Merkle branch of the block (list of hex strings)

Example Block Header containing the json format

{

 "id": "0d49aa74-0986-474f-a6eb-5913fbbbba02",
 "prevhash": "0000000000000000012811f570b3c0ff8cb93c44d707499dc2fcfdd611f38d93",
 "coinbaseValue": 1251906370,
 "version": 536870912,
 "nBits": "1802c73f",
 "time": 1585156824,
 "height": 627795,
 "merkleProof": [
   "f4cba40673d5573ca1aab2ee8fbd300102767561190cad7aa6211e04223ff6c3",
   "2d69511004ba72b60a10e6482491d689470b9f8527aff0f550c197d8a2446c45",
   "6eb9f4ef18f9669db60b21dc52292eba5318d684f7c476bb12da03b6d97d7c4f",
   "7a69a2fb7b132b36496501357d923ce584f913b37879a1930a10682d284bc2a9",
   "976089f04a73862fac14d2eec8b3f23aef9167f9804c40ade23c4f385cd92928",
   "73ec68c1692643e7edd22a34729f4bc8529fed48eca8ac0cd6e8b2929fb44064",
   "ee59af2b7964c1c0f48cd06b4e4e77c783711746030cc20d46a339f3d9993709",
   "6c0a33f1a1778ebec5d63172c55edb433ae365dbf7cd37bfa3535c864e9b9ea7",
   "d59744d6f3548adda90444a44eb16c56022554fdd4a0448632acd36058c96599",
   "6bd2d6dcdea8dd04345b7b706ba125ed73394be899355cb7b355d258eea20ff5",
   "3842aadab31a0e3bb5c484d58262f052afbe7f684935bf4d19ed614521e750e5",
   "91dec854c6f222b9be0cc78bd34b2405e98f34c6d2c7db8f84db6d85a83eb51e",
   "2b07dc2afdcafa3719c4ef440ef5c5f0c332efa174d23bbb72749680b36575a7"
 ]

}

The Maestro software handles the call to and from the SV node to the ASIC miner. The ASIC miner then performs the hashing process to discover the next suitable block to be placed on the blockchain.