Protocol Methods

blockchain.address.get_balance

Return the confirmed and unconfirmed balances of a Bitcoin Cash address.

Signature

blockchain.address.get_balance(address)

New in version 1.4.3.

  • address

    The address as a Cash Address string (with or without prefix, case insensitive). Some server implementations do not support Legacy (base58) addresses and are not required to do so by this specification. However, Fulcrum does support both Legacy and Cash Address encodings.

Result

blockchain.address.get_history

Return the confirmed and unconfirmed history of a Bitcoin Cash address.

Signature

blockchain.address.get_history(address)

New in version 1.4.3.

  • address

    The address as a Cash Address string (with or without prefix, case insensitive). Some server implementations do not support Legacy (base58) addresses and are not required to do so by this specification. However, Fulcrum does support both Legacy and Cash Address encodings.

Result

blockchain.address.get_mempool

Return the unconfirmed transactions of a Bitcoin Cash address.

Signature

blockchain.address.get_mempool(address)

New in version 1.4.3.

  • address

    The address as a Cash Address string (with or without prefix, case insensitive). Some server implementations do not support Legacy (base58) addresses and are not required to do so by this specification. However, Fulcrum does support both Legacy and Cash Address encodings.

Result

blockchain.address.get_scripthash

Translate a Bitcoin Cash address to a script hash. This method is potentially useful for clients preferring to work with script hashes but lacking the local libraries necessary to generate them.

Signature

blockchain.address.get_scripthash(address)

New in version 1.4.3.

  • address

    The address as a Cash Address string (with or without prefix, case insensitive). Some server implementations do not support Legacy (base58) addresses and are not required to do so by this specification. However, Fulcrum does support both Legacy and Cash Address encodings.

Result

The unique 32-byte hex-encoded script hash that corresponds to the decoded address.

blockchain.address.listunspent

Return an ordered list of UTXOs sent to a Bitcoin Cash address.

Signature

blockchain.address.listunspent(address)

New in version 1.4.3.

  • address

    The address as a Cash Address string (with or without prefix, case insensitive). Some server implementations do not support Legacy (base58) addresses and are not required to do so by this specification. However, Fulcrum does support both Legacy and Cash Address encodings.

Result

blockchain.address.subscribe

Subscribe to a Bitcoin Cash address.

Signature

blockchain.address.subscribe(address)

New in version 1.4.3.

address

The address as a Cash Address string (with or without prefix, case insensitive). Some server implementations do not support Legacy (base58) addresses and are not required to do so by this specification. However, Fulcrum does support both Legacy and Cash Address encodings.

Result

The status of the address.

Notifications

As this is a subcription, the client will receive a notification when the status of the address changes. Its signature is

blockchain.address.subscribe(address, status)

Note

The address returned back to the client when notifying of status changes will be in the same encoding and syle as was provided when subscribing. In effect, a whitespace-stripped version of the address string that the client provided will be sent back to the client when notifying, in order to make it easier for clients to track the notification.

It is unspecified what happens if a client subscribes to the same address using multiple encodings or styles, but it is RECOMMENDED that servers simply update their internal subscription tables on subsequent subscriptions to the same destination such that they honor the latest subscription only, and not subscribe clients multiple times to the same logical destination. For example, Fulcrum server will simply update its table for how to refer to the subscription and send clients subsequent notifications using the latest encoding style of that particular address that the client last provided.

Similarly, if a client mixes blockchain.address.* and blockchain.scripthash.* calls to the server, it is RECOMMENDED that the server treat all addresses as equivalent to their scripthashes internally such that it is possible to subscribe by address and later unsubscribe by scripthash, for example.

blockchain.address.unsubscribe

Unsubscribe from a Bitcoin Cash address, preventing future notifications if its status changes.

Signature

blockchain.address.unsubscribe(address)

New in version 1.4.3.

address

The address as a Cash Address string (with or without prefix, case insensitive). Some server implementations do not support Legacy (base58) addresses and are not required to do so by this specification. However, Fulcrum does support both Legacy and Cash Address encodings.

Result

Returns true if the address was previously subscribed-to, otherwise false. Note that false might be returned even for something subscribed-to earlier, because the server can drop subscriptions in rare circumstances.

blockchain.block.header

Return the block header at the given height.

Signature

blockchain.block.header(height, cp_height=0)

New in version 1.3.

Changed in version 1.4: cp_height parameter added

Changed in version 1.4.1.

height

The height of the block, a non-negative integer.

cp_height

Checkpoint height, a non-negative integer. Ignored if zero, otherwise the following must hold:

height <= cp_height

Result

If cp_height is zero, the raw block header as a hexadecimal string.

Otherwise a dictionary with the following keys. This provides a proof that the given header is present in the blockchain; presumably the client has the merkle root hard-coded as a checkpoint.

  • branch

    The merkle branch of header up to root, deepest pairing first.

  • header

    The raw block header as a hexadecimal string.

  • root

    The merkle root of all blockchain headers up to and including cp_height.

Example Result

With height 5 and cp_height 0 on the Bitcoin Cash chain:

"0100000085144a84488ea88d221c8bd6c059da090e88f8a2c99690ee55dbba4e00000000e11c48fecdd9e72510ca84f023370c9a38bf91ac5cae88019bee94d24528526344c36649ffff001d1d03e477"

With cp_height 8:

{
  "branch": [
     "000000004ebadb55ee9096c9a2f8880e09da59c0d68b1c228da88e48844a1485",
     "96cbbc84783888e4cc971ae8acf86dd3c1a419370336bb3c634c97695a8c5ac9",
     "965ac94082cebbcffe458075651e9cc33ce703ab0115c72d9e8b1a9906b2b636",
     "89e5daa6950b895190716dd26054432b564ccdc2868188ba1da76de8e1dc7591"
     ],
  "header": "0100000085144a84488ea88d221c8bd6c059da090e88f8a2c99690ee55dbba4e00000000e11c48fecdd9e72510ca84f023370c9a38bf91ac5cae88019bee94d24528526344c36649ffff001d1d03e477",
  "root": "e347b1c43fd9b5415bf0d92708db8284b78daf4d0e24f9c3405f45feb85e25db"
}

blockchain.block.headers

Return a concatenated chunk of block headers from the main chain.

Signature

blockchain.block.headers(start_height, count, cp_height=0)

New in version 1.2.

Changed in version 1.4: cp_height parameter added

Changed in version 1.4.1.

start_height

The height of the first header requested, a non-negative integer.

count

The number of headers requested, a non-negative integer.

cp_height

Checkpoint height, a non-negative integer. Ignored if zero, otherwise the following must hold:

start_height + (count - 1) <= cp_height

Result

A dictionary with the following members:

  • count

    The number of headers returned, between zero and the number requested. If the chain has not extended sufficiently far, only the available headers will be returned. If more headers than max were requested at most max will be returned.

  • hex

    The binary block headers concatenated together in-order as a hexadecimal string. Starting with version 1.4.1, AuxPoW data (if present in the original header) is truncated if cp_height is nonzero.

  • max

    The maximum number of headers the server will return in a single request.

The dictionary additionally has the following keys if count and cp_height are not zero. This provides a proof that all the given headers are present in the blockchain; presumably the client has the merkle root hard-coded as a checkpoint.

  • root

    The merkle root of all blockchain headers up to and including cp_height.

  • branch

    The merkle branch of the last returned header up to root, deepest pairing first.

Example Response

See here for an example of root and branch keys.

{
  "count": 2,
  "hex": "0100000000000000000000000000000000000000000000000000000000000000000000003ba3edfd7a7b12b27ac72c3e67768f617fc81bc3888a51323a9fb8aa4b1e5e4a29ab5f49ffff001d1dac2b7c010000006fe28c0ab6f1b372c1a6a246ae63f74f931e8365e15a089c68d6190000000000982051fd1e4ba744bbbe680e1fee14677ba1a3c3540bf7b1cdb606e857233e0e61bc6649ffff001d01e36299"
  "max": 2016
}

blockchain.estimatefee

Return the estimated transaction fee per kilobyte for a transaction to be confirmed within a certain number of blocks.

Signature

blockchain.estimatefee(number)

number

The number of blocks to target for confirmation.

Result

The estimated transaction fee in coin units per kilobyte, as a floating point number. If the daemon does not have enough information to make an estimate, the integer -1 is returned.

Example Result

0.00101079

blockchain.headers.subscribe

Subscribe to receive block headers when a new block is found.

Signature

blockchain.headers.subscribe()

Result

The header of the current block chain tip. The result is a dictionary with two members:

  • hex

    The binary header as a hexadecimal string.

  • height

    The height of the header, an integer.

Example Result

{
  "height": 520481,
  "hex": "00000020890208a0ae3a3892aa047c5468725846577cfcd9b512b50000000000000000005dc2b02f2d297a9064ee103036c14d678f9afc7e3d9409cf53fd58b82e938e8ecbeca05a2d2103188ce804c4"
}

Notifications

As this is a subcription, the client will receive a notification when a new block is found. The notification’s signature is:

blockchain.headers.subscribe(header)
  • header

    See Result above.

Note

Should a new block arrive quickly, perhaps while the server is still processing prior blocks, the server may only notify of the most recent chain tip. The protocol does not guarantee notification of all intermediate block headers.

In a similar way the client must be prepared to handle chain reorganisations. Should a re-org happen the new chain tip will not sit directly on top of the prior chain tip. The client must be able to figure out the common ancestor block and request any missing block headers to acquire a consistent view of the chain state.

blockchain.relayfee

Return the minimum fee a low-priority transaction must pay in order to be accepted to the daemon’s memory pool.

Signature

blockchain.relayfee()

Result

The fee in whole coin units (BTC, not satoshis for Bitcoin) as a floating point number.

Example Results

1e-05
0.0

blockchain.scripthash.get_balance

Return the confirmed and unconfirmed balances of a script hash.

Signature

blockchain.scripthash.get_balance(scripthash)

New in version 1.1.

scripthash

The script hash as a hexadecimal string.

Result

A dictionary with keys confirmed and unconfirmed. The value of each is the appropriate balance in satoshis.

Result Example

{
  "confirmed": 103873966,
  "unconfirmed": 236844
}

blockchain.scripthash.get_history

Return the confirmed and unconfirmed history of a script hash.

Signature

blockchain.scripthash.get_history(scripthash)

New in version 1.1.

scripthash

The script hash as a hexadecimal string.

Result

A list of confirmed transactions in blockchain order, with the output of blockchain.scripthash.get_mempool() appended to the list. Each confirmed transaction is a dictionary with the following keys:

  • height

    The integer height of the block the transaction was confirmed in.

  • tx_hash

    The transaction hash in hexadecimal.

See blockchain.scripthash.get_mempool() for how mempool transactions are returned.

Result Examples

[
  {
    "height": 200004,
    "tx_hash": "acc3758bd2a26f869fcc67d48ff30b96464d476bca82c1cd6656e7d506816412"
  },
  {
    "height": 215008,
    "tx_hash": "f3e1bf48975b8d6060a9de8884296abb80be618dc00ae3cb2f6cee3085e09403"
  }
]
[
  {
    "fee": 20000,
    "height": 0,
    "tx_hash": "9fbed79a1e970343fcd39f4a2d830a6bde6de0754ed2da70f489d0303ed558ec"
  }
]

blockchain.scripthash.get_mempool

Return the unconfirmed transactions of a script hash.

Signature

blockchain.scripthash.get_mempool(scripthash)

New in version 1.1.

scripthash

The script hash as a hexadecimal string.

Result

A list of mempool transactions in arbitrary order. Each mempool transaction is a dictionary with the following keys:

  • height

    0 if all inputs are confirmed, and -1 otherwise.

  • tx_hash

    The transaction hash in hexadecimal.

  • fee

    The transaction fee in minimum coin units (satoshis).

Result Example

[
  {
    "tx_hash": "45381031132c57b2ff1cbe8d8d3920cf9ed25efd9a0beb764bdb2f24c7d1c7e3",
    "height": 0,
    "fee": 24310
  }
]

blockchain.scripthash.listunspent

Return an ordered list of UTXOs sent to a script hash.

Signature

blockchain.scripthash.listunspent(scripthash)

New in version 1.1.

scripthash

The script hash as a hexadecimal string.

Result

A list of unspent outputs in blockchain order. This function takes the mempool into account. Mempool transactions paying to the address are included at the end of the list in an undefined order. Any output that is spent in the mempool does not appear. Each output is a dictionary with the following keys:

  • height

    The integer height of the block the transaction was confirmed in. 0 if the transaction is in the mempool.

  • tx_pos

    The zero-based index of the output in the transaction’s list of outputs.

  • tx_hash

    The output’s transaction hash as a hexadecimal string.

  • value

    The output’s value in minimum coin units (satoshis).

Result Example

[
  {
    "tx_pos": 0,
    "value": 45318048,
    "tx_hash": "9f2c45a12db0144909b5db269415f7319179105982ac70ed80d76ea79d923ebf",
    "height": 437146
  },
  {
    "tx_pos": 0,
    "value": 919195,
    "tx_hash": "3d2290c93436a3e964cfc2f0950174d8847b1fbe3946432c4784e168da0f019f",
    "height": 441696
  }
]

blockchain.scripthash.subscribe

Subscribe to a script hash.

Signature

blockchain.scripthash.subscribe(scripthash)

New in version 1.1.

scripthash

The script hash as a hexadecimal string.

Result

The status of the script hash.

Notifications

The client will receive a notification when the status of the script hash changes. Its signature is

blockchain.scripthash.subscribe(scripthash, status)

blockchain.scripthash.unsubscribe

Unsubscribe from a script hash, preventing future notifications if its status changes.

Signature

blockchain.scripthash.unsubscribe(scripthash)

New in version 1.4.2.

scripthash

The script hash as a hexadecimal string.

Result

Returns true if the scripthash was previously subscribed-to, otherwise false. Note that false might be returned even for something subscribed-to earlier, because the server can drop subscriptions in rare circumstances.

blockchain.transaction.broadcast

Broadcast a transaction to the network.

Signature

blockchain.transaction.broadcast(raw_tx)

Changed in version 1.1: errors returned as JSON RPC errors rather than as a result.

raw_tx

The raw transaction as a hexadecimal string.

Result

The transaction hash as a hexadecimal string.

Note protocol version 1.0 (only) does not respond according to the JSON RPC specification if an error occurs. If the daemon rejects the transaction, the result is the error message string from the daemon, as if the call were successful. The client needs to determine if an error occurred by comparing the result to the expected transaction hash.

Result Examples

"a76242fce5753b4212f903ff33ac6fe66f2780f34bdb4b33b175a7815a11a98e"

Protocol version 1.0 returning an error as the result:

"258: txn-mempool-conflict"

blockchain.transaction.dsproof.get

Returns information on a double-spend proof. The query can be by either tx_hash or dspid.

Signature

blockchain.transaction.dsproof.get(hash)

New in version 1.4.5.

hash

The transaction hash (or dspid) as a hexadecimal string.

Result

If the transaction in question has an associated dsproof, then a JSON object. Otherwise null.

Example Results:

{
  "dspid": "587d18bf8a64ede9c7450fdaeab27b9b3c46cfa8948f4c145f889601153c56b0",
  "txid": "5b59ce35093fbd13549cd6f203d4b5b01762d70e75b8e9733dfc463e0ff8cc13",
  "hex": "410c56078977120e828e4aacdd813a818d17c47d94183aa176d62c805d47697dddddf46c2ab68ee1e46a3e17aa7da548c38ec43416422d433b1782eb3298356df441",
  "outpoint": {
    "txid": "f6e2a16ba665d5402dad147fe35872961bc6961da62345a2171ee001cfcf7600",
    "vout": 0
  },
  "descendants": [
    "36fbb099e6de59d23477727e3199c65caae35ded957660f56fc681a6d81d5570",
    "5b59ce35093fbd13549cd6f203d4b5b01762d70e75b8e9733dfc463e0ff8cc13"
  ]
}

blockchain.transaction.dsproof.list

List all of the transactions that currently have double-spend proofs associated with them.

Signature

blockchain.transaction.dsproof.list()

New in version 1.4.5.

Result

A JSON array of hexadecimal strings. May be empty. Each string is a transaction hash of an in-mempool transaction that has a double-spend proof associated with it. Each of the hashes appearing in the list may be given as an argument to blockchain.transaction.dsproof.get() in order to obtain the associated double-spend proof for that transaction.

Example Results:

[
  "e67cc122f3c28a4243c3a1b14b38a9474c22ba928af9a194ca2b85426f0fd1bb",
  "077f0cc2439f2e48567c72eeeba5a447f8649c00c3d18ab6516eccfd4119726f",
  "ccc2f0d90b7067a83566024d4df842f0b6cb8180e18d642fcc85cae8acadbd58"
]

blockchain.transaction.dsproof.subscribe

Subscribe for dsproof notifications for a transaction.

Signature

blockchain.transaction.dsproof.subscribe(tx_hash)

New in version 1.4.5.

tx_hash

The transaction hash as a hexadecimal string.

Result

A result identical to what one would get from blockchain.transaction.dsproof.get().

Notifications

The client will receive a notification when the dsproof status of the transaction changes. Its signature is

blockchain.transction.dsproof.subscribe(tx_hash, dsproof)

With dsproof being identical to what one would get from invoking blockchain.transaction.dsproof.get() for that particular tx_hash.

blockchain.transaction.dsproof.unsubscribe

Unsubscribe from receiving any further dsproof notifications for a transaction.

Signature

blockchain.transaction.dsproof.unsubscribe(tx_hash)

New in version 1.4.5.

tx_hash

The transaction hash as a hexadecimal string.

Result

Returns true if the transaction was previously subscribed-to for dsproof notifications, otherwise false. Note that false might be returned even for something subscribed-to earlier, because the server can drop subscriptions in rare circumstances.

blockchain.transaction.get

Return a raw transaction.

Signature

blockchain.transaction.get(tx_hash, verbose=false)

Changed in version 1.1: ignored argument height removed

Changed in version 1.2: verbose argument added

tx_hash

The transaction hash as a hexadecimal string.

verbose

Whether a verbose coin-specific response is required.

Result

If verbose is false:

The raw transaction as a hexadecimal string.

If verbose is true:

The result is a coin-specific dictionary – whatever the coin daemon returns when asked for a verbose form of the raw transaction.

Example Results

When verbose is false:

"01000000015bb9142c960a838329694d3fe9ba08c2a6421c5158d8f7044cb7c48006c1b48"
"4000000006a4730440220229ea5359a63c2b83a713fcc20d8c41b20d48fe639a639d2a824"
"6a137f29d0fc02201de12de9c056912a4e581a62d12fb5f43ee6c08ed0238c32a1ee76921"
"3ca8b8b412103bcf9a004f1f7a9a8d8acce7b51c983233d107329ff7c4fb53e44c855dbe1"
"f6a4feffffff02c6b68200000000001976a9141041fb024bd7a1338ef1959026bbba86006"
"4fe5f88ac50a8cf00000000001976a91445dac110239a7a3814535c15858b939211f85298"
"88ac61ee0700"

When verbose is true:

{
  "blockhash": "0000000000000000015a4f37ece911e5e3549f988e855548ce7494a0a08b2ad6",
  "blocktime": 1520074861,
  "confirmations": 679,
  "hash": "36a3692a41a8ac60b73f7f41ee23f5c917413e5b2fad9e44b34865bd0d601a3d",
  "hex": "01000000015bb9142c960a838329694d3fe9ba08c2a6421c5158d8f7044cb7c48006c1b484000000006a4730440220229ea5359a63c2b83a713fcc20d8c41b20d48fe639a639d2a8246a137f29d0fc02201de12de9c056912a4e581a62d12fb5f43ee6c08ed0238c32a1ee769213ca8b8b412103bcf9a004f1f7a9a8d8acce7b51c983233d107329ff7c4fb53e44c855dbe1f6a4feffffff02c6b68200000000001976a9141041fb024bd7a1338ef1959026bbba860064fe5f88ac50a8cf00000000001976a91445dac110239a7a3814535c15858b939211f8529888ac61ee0700",
  "locktime": 519777,
  "size": 225,
  "time": 1520074861,
  "txid": "36a3692a41a8ac60b73f7f41ee23f5c917413e5b2fad9e44b34865bd0d601a3d",
  "version": 1,
  "vin": [ {
    "scriptSig": {
      "asm": "30440220229ea5359a63c2b83a713fcc20d8c41b20d48fe639a639d2a8246a137f29d0fc02201de12de9c056912a4e581a62d12fb5f43ee6c08ed0238c32a1ee769213ca8b8b[ALL|FORKID] 03bcf9a004f1f7a9a8d8acce7b51c983233d107329ff7c4fb53e44c855dbe1f6a4",
      "hex": "4730440220229ea5359a63c2b83a713fcc20d8c41b20d48fe639a639d2a8246a137f29d0fc02201de12de9c056912a4e581a62d12fb5f43ee6c08ed0238c32a1ee769213ca8b8b412103bcf9a004f1f7a9a8d8acce7b51c983233d107329ff7c4fb53e44c855dbe1f6a4"
    },
    "sequence": 4294967294,
    "txid": "84b4c10680c4b74c04f7d858511c42a6c208bae93f4d692983830a962c14b95b",
    "vout": 0}],
  "vout": [ { "n": 0,
             "scriptPubKey": { "addresses": [ "12UxrUZ6tyTLoR1rT1N4nuCgS9DDURTJgP"],
                               "asm": "OP_DUP OP_HASH160 1041fb024bd7a1338ef1959026bbba860064fe5f OP_EQUALVERIFY OP_CHECKSIG",
                               "hex": "76a9141041fb024bd7a1338ef1959026bbba860064fe5f88ac",
                               "reqSigs": 1,
                               "type": "pubkeyhash"},
             "value": 0.0856647},
           { "n": 1,
             "scriptPubKey": { "addresses": [ "17NMgYPrguizvpJmB1Sz62ZHeeFydBYbZJ"],
                               "asm": "OP_DUP OP_HASH160 45dac110239a7a3814535c15858b939211f85298 OP_EQUALVERIFY OP_CHECKSIG",
                               "hex": "76a91445dac110239a7a3814535c15858b939211f8529888ac",
                               "reqSigs": 1,
                               "type": "pubkeyhash"},
             "value": 0.1360904}]}

blockchain.transaction.get_height

Returns the block height for a confirmed transaction, or 0 for a mempool transaction, given its hash.

Signature

blockchain.transaction.get_height(tx_hash)

New in version 1.4.5.

tx_hash

The transaction hash as a hexadecimal string.

Result

Either a numeric value or null.

  • Numeric values > 0

    The transaction is confirmed at this block height.

  • Numeric values == 0

    The transaction is not confirmed but is in the mempool.

  • null

    The transaction is unknown.

blockchain.transaction.get_merkle

Return the merkle branch to a confirmed transaction given its hash and, optionally, its height.

Signature

blockchain.transaction.get_merkle(tx_hash[, height])

Changed in version 1.4.5: height is no longer required and is now optional

tx_hash

The transaction hash as a hexadecimal string.

height (optional in 1.4.5 or above)

The height at which it was confirmed, an integer. As of version 1.4.5 of the protocol, this second argument may be omitted, however if it is included the lookup may return the results slightly faster since an extra database lookup is avoided on the server-side.

Result

A dictionary with the following keys:

  • block_height

    The height of the block the transaction was confirmed in.

  • merkle

    A list of transaction hashes the current hash is paired with, recursively, in order to trace up to obtain merkle root of the block, deepest pairing first.

  • pos

    The 0-based index of the position of the transaction in the ordered list of transactions in the block.

Result Example

{
  "merkle":
  [
    "713d6c7e6ce7bbea708d61162231eaa8ecb31c4c5dd84f81c20409a90069cb24",
    "03dbaec78d4a52fbaf3c7aa5d3fccd9d8654f323940716ddf5ee2e4bda458fde",
    "e670224b23f156c27993ac3071940c0ff865b812e21e0a162fe7a005d6e57851",
    "369a1619a67c3108a8850118602e3669455c70cdcdb89248b64cc6325575b885",
    "4756688678644dcb27d62931f04013254a62aeee5dec139d1aac9f7b1f318112",
    "7b97e73abc043836fd890555bfce54757d387943a6860e5450525e8e9ab46be5",
    "61505055e8b639b7c64fd58bce6fc5c2378b92e025a02583303f69930091b1c3",
    "27a654ff1895385ac14a574a0415d3bbba9ec23a8774f22ec20d53dd0b5386ff",
    "5312ed87933075e60a9511857d23d460a085f3b6e9e5e565ad2443d223cfccdc",
    "94f60b14a9f106440a197054936e6fb92abbd69d6059b38fdf79b33fc864fca0",
    "2d64851151550e8c4d337f335ee28874401d55b358a66f1bafab2c3e9f48773d"
  ],
  "block_height": 450538,
  "pos": 710
}

blockchain.transaction.id_from_pos

Return a transaction hash and optionally a merkle proof, given a block height and a position in the block.

Signature

blockchain.transaction.id_from_pos(height, tx_pos, merkle=false)

New in version 1.4.

height

The main chain block height, a non-negative integer.

tx_pos

A zero-based index of the transaction in the given block, an integer.

merkle

Whether a merkle proof should also be returned, a boolean.

Result

If merkle is false, the transaction hash as a hexadecimal string. If true, a dictionary with the following keys:

  • tx_hash

    The transaction hash as a hexadecimal string.

  • merkle

    A list of transaction hashes the current hash is paired with, recursively, in order to trace up to obtain merkle root of the block, deepest pairing first.

Example Results

When merkle is false:

"fc12dfcb4723715a456c6984e298e00c479706067da81be969e8085544b0ba08"

When merkle is true:

{
  "tx_hash": "fc12dfcb4723715a456c6984e298e00c479706067da81be969e8085544b0ba08",
  "merkle":
  [
    "928c4275dfd6270349e76aa5a49b355eefeb9e31ffbe95dd75fed81d219a23f8",
    "5f35bfb3d5ef2ba19e105dcd976928e675945b9b82d98a93d71cbad0e714d04e",
    "f136bcffeeed8844d54f90fc3ce79ce827cd8f019cf1d18470f72e4680f99207",
    "6539b8ab33cedf98c31d4e5addfe40995ff96c4ea5257620dfbf86b34ce005ab",
    "7ecc598708186b0b5bd10404f5aeb8a1a35fd91d1febbb2aac2d018954885b1e",
    "a263aae6c470b9cde03b90675998ff6116f3132163911fafbeeb7843095d3b41",
    "c203983baffe527edb4da836bc46e3607b9a36fa2c6cb60c1027f0964d971b29",
    "306d89790df94c4632d652d142207f53746729a7809caa1c294b895a76ce34a9",
    "c0b4eff21eea5e7974fe93c62b5aab51ed8f8d3adad4583c7a84a98f9e428f04",
    "f0bd9d2d4c4cf00a1dd7ab3b48bbbb4218477313591284dcc2d7ca0aaa444e8d",
    "503d3349648b985c1b571f59059e4da55a57b0163b08cc50379d73be80c4c8f3"
  ]
}

blockchain.transaction.subscribe

Subscribe to a transaction in order to receive future notifications if its confirmation status changes.

Signature

blockchain.transaction.subscribe(tx_hash)

New in version 1.4.5.

tx_hash

The transaction hash as a hexadecimal string.

Result

A result identical to what one would get from blockchain.transaction.get_height().

Notifications

The client will receive a notification when the confirmation status of the transaction changes. Its signature is

blockchain.transction.subscribe(tx_hash, height)

With height being identical to what one would get from invoking blockchain.transaction.get_height().

blockchain.transaction.unsubscribe

Unsubscribe from a transaction, preventing future notifications if its confirmation status changes.

Signature

blockchain.transaction.unsubscribe(tx_hash)

New in version 1.4.5.

tx_hash

The transaction hash as a hexadecimal string.

Result

Returns true if the transaction was previously subscribed-to, otherwise false. Note that false might be returned even for something subscribed-to earlier, because the server can drop subscriptions in rare circumstances.

blockchain.utxo.get_info

Return information for an unspent transaction output.

Signature

blockchain.utxo.get_info(tx_hash, out_n)

New in version 1.4.4.

tx_hash

The UTXO’s transaction hash as a hexadecimal string.

out_n

The UTXO’s transaction output number. This should be a number in the range 0 <= out_n <= 65535

Result

If the UTXO in question does not exist or is spent, null is returned. Otherwise, a dictionary will be returned containing the following keys:

  • confirmed_height

    (Optional) The integer height of the block the UTXO’s transaction was confirmed in. This key will be missing from the dictionary if the transaction is in the mempool and is not yet confirmed.

  • scripthash

    The output’s destination script hash as a hexadecimal string.

  • value

    The output’s value in integer minimum coin units (satoshis).

Result Example

{
  "confirmed_height": 602123,
  "scripthash": "1c1e184c97abc87626c497b95f755df1025f48b9c27d037ea335677c57f38e5c",
  "value": 45318048
}

mempool.get_fee_histogram

Return a histogram of the fee rates paid by transactions in the memory pool, weighted by transaction size.

Signature

mempool.get_fee_histogram()

New in version 1.2.

Result

The histogram is an array of [fee, vsize] pairs, where vsizen is the cumulative virtual size of mempool transactions with a fee rate in the interval [feen-1, feen], and feen-1 > feen.

Fee intervals may have variable size. The choice of appropriate intervals is currently not part of the protocol.

Example Result

[[12, 128812], [4, 92524], [2, 6478638], [1, 22890421]]

server.add_peer

A newly-started server uses this call to get itself into other servers’ peers lists. It sould not be used by wallet clients.

Signature

server.add_peer(features)

New in version 1.1.

  • features

    The same information that a call to the sender’s server.features() RPC call would return.

Result

A boolean indicating whether the request was tentatively accepted. The requesting server will appear in server.peers.subscribe() when further sanity checks complete successfully.

server.banner

Return a banner to be shown in the Electron Cash console.

Signature

server.banner()

Result

A string.

Example Result

"Welcome to Fulcrum!"

server.donation_address

Return a server donation address.

Signature

server.donation_address()

Result

A string.

Example Result

"1BWwXJH3q6PRsizBkSGm2Uw4Sz1urZ5sCj"

server.features

Return a list of features and services supported by the server.

Signature

server.features()

Changed in version 1.4.2: hosts key is no longer required, but recommended.

Changed in version 1.4.5: dsproof key added (optional).

Result

A dictionary of keys and values. Each key represents a feature or service of the server, and the value gives additional information.

The following features MUST be reported by the server. Additional key-value pairs may be returned.

  • genesis_hash

    The hash of the genesis block. This is used to detect if a peer is connected to one serving a different network.

  • hash_function

    The hash function the server uses for script hashing. The client must use this function to hash pay-to-scripts to produce script hashes to send to the server. The default is “sha256”. “sha256” is currently the only acceptable value.

  • server_version

    A string that identifies the server software. Should be the same as the result to the server.version() RPC call.

  • protocol_max

  • protocol_min

    Strings that are the minimum and maximum Electrum Cash protocol versions this server speaks. Example: “1.1”.

  • pruning

    An integer, the pruning limit. Omit or set to null if there is no pruning limit. Should be the same as what would suffix the letter p in the IRC real name.

The following features are RECOMMENDED that be reported by the servers.

  • hosts

    A dictionary, keyed by host name, that this server can be reached at. If this dictionary is missing, then this is a way to signal to other servers that while this host is reachable, it does not wish to peer with other servers. A server SHOULD stop peering with a peer if it sees the hosts dictionary for its peer is empty and/or no longer contains the expected route (e.g. hostname). Normally this dictionary will only contain a single entry; other entries can be used in case there are other connection routes (e.g. Tor).

    The value for a host is itself a dictionary, with the following optional keys:

    • ssl_port

      An integer. Omit or set to null if SSL connectivity is not provided.

    • tcp_port

      An integer. Omit or set to null if TCP connectivity is not provided.

    • ws_port

      An integer. Omit or set to null if Web Socket (ws://) connectivity is not provided.

    • wss_port

      An integer. Omit or set to null if Web Socket Secure (wss://) connectivity is not provided.

    A server should ignore information provided about any host other than the one it connected to.

  • dsproof

    A boolean value. If present and set to true, then the server has double-spend proof support, and it supports the blockchain.transaction.dsproof.* set of RPC methods. If this key is missing or false, then the server does not support dsproofs.

Example Result

{
    "genesis_hash": "000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943",
    "hosts": {"14.3.140.101": {"tcp_port": 51001, "ssl_port": 51002}},
    "protocol_max": "1.4",
    "protocol_min": "1.4.3",
    "pruning": null,
    "server_version": "Fulcrum 1.0.5",
    "hash_function": "sha256",
    "dsproof": true
}

server.peers.subscribe

Return a list of peer servers. Despite the name this is not a subscription and the server must send no notifications.

Signature

server.peers.subscribe()

Result

An array of peer servers, each returned as a 3-element array. For example:

["107.150.45.210",
 "e.anonyhost.org",
 ["v1.0", "p10000", "t", "s995"]]

The first element is the IP address, the second is the host name (which might also be an IP address), and the third is a list of server features. Each feature and starts with a letter. ‘v’ indicates the server maximum protocol version, ‘p’ its pruning limit and is omitted if it does not prune, ‘t’ is the TCP port number, and ‘s’ is the SSL port number. If a port is not given for ‘s’ or ‘t’ the default port for the coin network is implied. If ‘s’ or ‘t’ is missing then the server does not support that transport.

server.ping

Ping the server to ensure it is responding, and to keep the session alive. The server may disconnect clients that have sent no requests for roughly 10 minutes.

Signature

server.ping()

New in version 1.2.

Result

Returns null.

server.version

Identify the client to the server and negotiate the protocol version. Only the first server.version() message is accepted.

Signature

server.version(client_name="", protocol_version="1.4")
  • client_name

    A string identifying the connecting client software.

  • protocol_version

    An array [protocol_min, protocol_max], each of which is a string. If protocol_min and protocol_max are the same, they can be passed as a single string rather than as an array of two strings, as for the default value.

The server should use the highest protocol version both support:

version = min(client.protocol_max, server.protocol_max)

If this is below the value:

max(client.protocol_min, server.protocol_min)

then there is no protocol version in common and the server must close the connection. Otherwise it should send a response appropriate for that protocol version.

Result

An array of 2 strings:

[server_software_version, protocol_version]

identifying the server and the protocol version that will be used for future communication.

Example:

server.version("Electron Cash 3.3.6", ["1.2", "1.4"])

Example Result:

["Fulcrum 1.0.5", "1.4"]