Protocol Methods

blockchain.address.get_balance

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

Signature

.. function:: blockchain.address.get_balance(address, [token_filter])
.. versionadded:: 1.4.3
.. versionchanged:: 1.5.0
   Added optional arg: *token_filter* (BCH only)
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.

token_filter (optional, BCH only)

A string, one of: :const:`"include_tokens"`, :const:`"exclude_tokens"` or :const:`"tokens_only"`. This controls whether the balance also includes :ref:`CashToken <cashtokens>`-containing UTXOs, whether to exclude them, or whether to return the balance for :ref:`CashToken <cashtokens>` UTXOs only, respectively.

The default is :const:`"exclude_tokens"` if the client :ref:`negotiated version <version negotiation>` 1.4.x or below with the server. If the client :ref:`negotiated version <version negotiation>` 1.5.0 or above, the default is :const:`"include_tokens"`.

Result

See :func:`blockchain.scripthash.get_balance`.

blockchain.address.get_first_use

Retrieve information on the first occurrence of a Bitcoin Cash address on the block chain.

Signature

.. function:: blockchain.address.get_first_use(address)
.. versionadded:: 1.5.2
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

As for :func:`blockchain.scripthash.get_first_use`.

blockchain.address.get_history

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

Signature

.. function:: blockchain.address.get_history(address, from_height=0, to_height=-1)
.. versionadded:: 1.4.3
.. versionchanged:: 1.5.1
   Allow pagination of history (added from_height, to_height)
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.

from_height

The first block height (inclusive) of the interval the client is interested in. A non-negative integer. Optional.

to_height

The last block height (exclusive) of the interval the client is interested in. A non-negative integer, or -1. Optional. A value of -1 means that the interval extends to the chaintip and also includes unconfirmed/mempool transactions (otherwise mempool txs are not included). from_height <= to_height must hold (for the purposes of this inequality and others here, treat a value of -1 as infinity).

Result

As for :func:`blockchain.scripthash.get_history`.

blockchain.address.get_mempool

Return the unconfirmed transactions of a Bitcoin Cash address.

Signature

.. function:: blockchain.address.get_mempool(address)
.. versionadded:: 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

As for :func:`blockchain.scripthash.get_mempool`.

blockchain.address.get_scripthash

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

Signature

.. function:: blockchain.address.get_scripthash(address)
.. versionadded:: 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 :ref:`script hash <script hashes>` that corresponds to the decoded address.

blockchain.address.listunspent

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

Signature

.. function:: blockchain.address.listunspent(address, [token_filter])
.. versionadded:: 1.4.3
.. versionchanged:: 1.5.0
   Added optional arg: *token_filter* (BCH only).
   *token_data* may appear in the result object if the UTXO contains a :ref:`CashToken <cashtokens>` (BCH only).
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.

token_filter (optional, BCH only)

A string, one of: :const:`"include_tokens"`, :const:`"exclude_tokens"` or :const:`"tokens_only"`. This controls whether the results also include :ref:`CashToken <cashtokens>`-containing UTXOs, whether to exclude them, or whether to return :ref:`CashToken <cashtokens>` UTXOs only, respectively.

The default is :const:`"exclude_tokens"` if the client :ref:`negotiated version <version negotiation>` 1.4.x or below with the server. If the client :ref:`negotiated version <version negotiation>` 1.5.0 or above, the default is :const:`"include_tokens"`.

Result

As for :func:`blockchain.scripthash.listunspent`.

blockchain.address.subscribe

Subscribe to a Bitcoin Cash address.

Signature

.. function:: blockchain.address.subscribe(address)
.. versionadded:: 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 :ref:`status <status>` of the address.

Notifications

As this is a subcription, the client will receive a notification when the :ref:`status <status>` of the address changes. Its signature is
.. function:: blockchain.address.subscribe(address, status)
   :noindex:
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 :ref:`status <status>` changes.

Signature

.. function:: blockchain.address.unsubscribe(address)
.. versionadded:: 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 :const:`true` if the address was previously subscribed-to, otherwise :const:`false`. Note that :const:`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

.. function:: blockchain.block.header(height, cp_height=0)
.. versionadded:: 1.3
.. versionchanged:: 1.4
   *cp_height* parameter added
.. versionchanged:: 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

.. function:: blockchain.block.headers(start_height, count, cp_height=0)
.. versionadded:: 1.2
.. versionchanged:: 1.4
   *cp_height* parameter added
.. versionchanged:: 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 :ref:`here <cp_height example>` 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

.. function:: 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.header.get

Retrieve a block header by its hash (or, optionally, its height).

Signature

.. function:: blockchain.header.get(block_hash)
.. versionadded:: 1.5.2
block_hash

A 64-character hexadecimal string indicating the block hash of the block for which to retrieve the header. Optionally, this can also be a numeric value and in that case it will be interpreted as a block height.

Result

The height and header of the requested block. The result is a dictionary with two keys:

height

The height of the header, an integer.

hex

The binary header as a hexadecimal string.

Example Result

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

blockchain.headers.get_tip

Get the latest block's height and header.

Signature

.. function:: blockchain.headers.get_tip()

.. versionadded:: 1.5.0

Result

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

height

The height of the header, an integer.

hex

The binary header as a hexadecimal string.

Example Result

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

blockchain.headers.subscribe

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

Signature

.. function:: blockchain.headers.subscribe()

Result

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

height

The height of the header, an integer.

hex

The binary header as a hexadecimal string.

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:
.. function:: blockchain.headers.subscribe(header)
   :noindex:
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.headers.unsubscribe

Undoes the effects of a previous call to :func:`blockchain.headers.subscribe`, that is to say: unsubscribe from receiving block header notifications.

Signature

.. function:: blockchain.headers.unsubscribe()

.. versionadded:: 1.5.0

Result

Returns :const:`true` if the client was previously subscribed to receive block header notifications, otherwise :const:`false`.

blockchain.relayfee

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

Signature

.. function:: 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.reusable.get_history

Return the confirmed transactions for an :ref:`rpa_prefix <rpa prefix>`.

Deprecated

This function is provided for compatibility with existing clients. Please use :func:`blockchain.rpa.get_history` in new code instead.

Signature

.. function:: blockchain.reusable.get_history(from_height, count, rpa_prefix)

.. versionadded:: 1.5.3

Availability

Only provided by servers that advertise as having the RPA index enabled. That is, servers that have the :const:`"rpa"` key present in their :func:`server.features` dictionary.

blockchain.reusable.get_mempool

Return the unconfirmed (mempool) transactions for an :ref:`rpa_prefix <rpa prefix>`.

Deprecated

This function is provided for compatibility with existing clients. Please use :func:`blockchain.rpa.get_mempool` in new code instead.

Signature

.. function:: blockchain.reusable.get_mempool(rpa_prefix)

.. versionadded:: 1.5.3

Availability

Only provided by servers that advertise as having the RPA index enabled. That is, servers that have the :const:`"rpa"` key present in their :func:`server.features` dictionary.

blockchain.rpa.get_history

Return the confirmed history of an :ref:`rpa_prefix <rpa prefix>`.

Signature

.. function:: blockchain.rpa.get_history(rpa_prefix, from_height, to_height=-1)
.. versionadded:: 1.5.3
rpa_prefix

The RPA prefix for which to scan for history, as a hexadecimal string, e.g. :const:`"ff"` or :const:`"ab"` or :const:`"abc"`. Note that this prefix must respect the server's :func:`server.features` :const:`prefix_bits_min` (default: :const:`8`), so if the server is configured with :const:`8`, then :const:`"ff"` will work but :const:`"f"` will not, however if it is configured with :const:`4`, then :const:`"f"` (a single nybble as a prefix) will work.

from_height

The first block height (inclusive) of the interval the client is interested in. A non-negative integer.

to_height

The last block height (exclusive) of the interval the client is interested in. A non-negative integer, or :const:`-1`. Optional. A value of :const:`-1` means that the interval extends to the chaintip, or up to the server's :func:`server.features` :const:`history_block_limit` (default: 60), whichever is less. :const:`from_height <= to_height` must hold (for the purposes of this inequality and others here, treat a value of :const:`-1` as infinity).

Availability

Only provided by servers that advertise as having the RPA index enabled. That is, servers that have the :const:`"rpa"` key present in their :func:`server.features` dictionary.

Result

A list of confirmed transactions in blockchain order. Note that unlike :func:`blockchain.scripthash.get_history`, no mempool transactions are ever returned by this call. For mempool RPA transactions, use :func:`blockchain.rpa.get_mempool`. 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.

Result Examples

[
  {
    "height": 825000,
    "tx_hash": "acc3758bd2a26f869fcc67d48ff30b96464d476bca82c1cd6656e7d506816412"
  },
  {
    "height": 825008,
    "tx_hash": "f3e1bf48975b8d6060a9de8884296abb80be618dc00ae3cb2f6cee3085e09403"
  }
]

blockchain.rpa.get_mempool

Return the unconfirmed (mempool) transactions for an :ref:`rpa_prefix <rpa prefix>`.

Signature

.. function:: blockchain.rpa.get_mempool(rpa_prefix)
.. versionadded:: 1.5.3
rpa_prefix

The RPA prefix for which to scan for mempool transactions, as a hexadecimal string, e.g. :const:`"ff"` or :const:`"ab"` or :const:`"abc"`. Note that this prefix must respect the server's :func:`server.features` :const:`prefix_bits_min` (default: :const:`8`), so if the server is configured with :const:`8`, then :const:`"ff"` will work but :const:`"f"` will not, however if it is configured with :const:`4`, then :const:`"f"` (a single nybble as a prefix) will work.

Availability

Only provided by servers that advertise as having the RPA index enabled. That is, servers that have the :const:`"rpa"` key present in their :func:`server.features` dictionary.

Result

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

height

:const:`0` for transactions with no unconfirmed parents, :const:`-1` for transactions that have unconfirmed parents in the mempool.

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
  },
  {
    "tx_hash": "354a24a255488c28c9cdfe7134d1b86bb99bbcca2bc7996b9613990bed384cc8",
    "height": -1,
    "fee": 185
  }
]

blockchain.scripthash.get_balance

Return the confirmed and unconfirmed balances of a :ref:`script hash <script hashes>`.

Signature

.. function:: blockchain.scripthash.get_balance(scripthash, [token_filter])
.. versionadded:: 1.1
.. versionchanged:: 1.5.0
   Added optional arg: *token_filter* (BCH only)
scripthash

The script hash as a hexadecimal string.

token_filter (optional, BCH only)

A string, one of: :const:`"include_tokens"`, :const:`"exclude_tokens"` or :const:`"tokens_only"`. This controls whether the balance also includes :ref:`CashToken <cashtokens>`-containing UTXOs, whether to exclude them, or whether to return the balance for :ref:`CashToken <cashtokens>` UTXOs only, respectively.

The default is :const:`"exclude_tokens"` if the client :ref:`negotiated version <version negotiation>` 1.4.x or below with the server. If the client :ref:`negotiated version <version negotiation>` 1.5.0 or above, the default is :const:`"include_tokens"`.

Result

A dictionary with keys confirmed and unconfirmed. The value of each is the appropriate balance in satoshis. Note that on BCH, be sure to select the appropriate token_filter argument to retrieve the balance either including or omitting tokens or for tokens only.

Result Example

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

blockchain.scripthash.get_first_use

Retrieve information on the first occurrence of a :ref:`script hash <script hashes>` on the block chain.

Note: On block chians such as BTC that use natural ordering, the first occurrence of any :ref:`script hash <script hashes>` will always be it appearing in an output of a transaction (since an address must receive funds before it can spend them). For block chains such as Bitcoin Cash, this is not always the case due to CTOR (txid based sorting of block transactions).

Signature

.. function:: blockchain.scripthash.get_first_use(scripthash)
.. versionadded:: 1.5.2
scripthash

The :ref:`script hash <script hashes>` as a hexadecimal string.

Result

If the :ref:`script hash <script hashes>` in question does not appear either on the block chain or in the mempool, then :const:`null` is returned. Otherwise, a dictionary containing the following keys:

block_hash

The block hash of the block where this :ref:`script hash <script hashes>` first appears, as a hexadecimal string. If this :ref:`script hash <script hashes>` first appears in the mempool, then this will be all zeroes, e.g. 64 hexadecimal :const:`0` digits.

height

The integer height of the block where this :ref:`script hash <script hashes>` first appears. If this :ref:`script hash <script hashes>` first appears in the mempool, then this will be :const:`0`.

Note: Unlike other protocol methods (such as :func:`blockchain.scripthash.get_mempool`), :const:`0` is always used here for any mempool transaction irrespective of whether it has any unconfirmed parents or not.

tx_hash

The transaction hash where this :ref:`script hash <script hashes>` first appears, in hexadecimal.

Note: For multiple mempool transactions referencing the same :ref:`script hash <script hashes>`, an unspecified transaction will be arbitrarily chosen and it may not always be the first one that appeared in the mempool for this :ref:`script hash <script hashes>`.

Result Examples

{
  "block_hash": "000000000000032e1219acd8cdda073f5cbb42a216fede788ad4b555e7969a26",
  "height": 200004,
  "tx_hash": "acc3758bd2a26f869fcc67d48ff30b96464d476bca82c1cd6656e7d506816412"
}

{
  "block_hash": "0000000000000000000000000000000000000000000000000000000000000000",
  "height": 0,
  "tx_hash": "9fbed79a1e970343fcd39f4a2d830a6bde6de0754ed2da70f489d0303ed558ec"
}

blockchain.scripthash.get_history

Return the confirmed and unconfirmed history of a :ref:`script hash <script hashes>`.

Signature

.. function:: blockchain.scripthash.get_history(scripthash, from_height=0, to_height=-1)
.. versionadded:: 1.1
.. versionchanged:: 1.5.1
   Allow pagination of history (added from_height, to_height)
scripthash

The script hash as a hexadecimal string.

from_height

The first block height (inclusive) of the interval the client is interested in. A non-negative integer. Optional.

to_height

The last block height (exclusive) of the interval the client is interested in. A non-negative integer, or -1. Optional. A value of -1 means that the interval extends to the chaintip and also includes unconfirmed/mempool transactions (otherwise mempool txs are not included). from_height <= to_height must hold (for the purposes of this inequality and others here, treat a value of -1 as infinity).

Result

A list of confirmed transactions in blockchain order, with the output of :func:`blockchain.scripthash.get_mempool` appended to the list (mempool is appended only if to_height is -1). 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.

Note that as of Fulcrum 1.8.0 the transaction history for a script hash also includes transactions that involve sending/receiving :ref:`CashTokens <cashtokens>` to/from that script hash.

See :func:`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 :ref:`script hash <script hashes>`.

Signature

.. function:: blockchain.scripthash.get_mempool(scripthash)
.. versionadded:: 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).

Note that as of Fulcrum 1.8.0 the mempool transactions for a script hash also include transactions that involve sending/receiving :ref:`CashTokens <cashtokens>` to/from that script hash.

Result Example

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

blockchain.scripthash.listunspent

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

Signature

.. function:: blockchain.scripthash.listunspent(scripthash, [token_filter])
.. versionadded:: 1.1
.. versionchanged:: 1.5.0
   Added optional arg: *token_filter* (BCH only).
   *token_data* may appear in the result object if the UTXO contains a :ref:`CashToken <cashtokens>` (BCH only).
scripthash

The script hash as a hexadecimal string.

token_filter (optional, BCH only)

A string, one of: :const:`"include_tokens"`, :const:`"exclude_tokens"` or :const:`"tokens_only"`. This controls whether the results also include :ref:`CashToken <cashtokens>`-containing UTXOs, whether to exclude them, or whether to return :ref:`CashToken <cashtokens>` UTXOs only, respectively.

The default is :const:`"exclude_tokens"` if the client :ref:`negotiated version <version negotiation>` 1.4.x or below with the server. If the client :ref:`negotiated version <version negotiation>` 1.5.0 or above, the default is :const:`"include_tokens"`.

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.

token_data (optional, BCH only)

A dictionary encapsulating the :ref:`CashToken data <token_data>` for this output. This key will be missing from the dictionary if the unspent output does not have any token data on it.

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

[
  {
    "height": 37146,
    "tx_hash": "9f2c45a12db0144909b5db269415f7319179105982ac70ed80d76ea79d923ebf",
    "tx_pos": 0,
    "value": 45318048
  },
  {
    "height": 41696,
    "tx_hash": "3d2290c93436a3e964cfc2f0950174d8847b1fbe3946432c4784e168da0f019f",
    "tx_pos": 0,
    "value": 919195
  },
  {
    "height": 126184,
    "token_data": {
      "amount": "1000000",
      "category": "8fd6a2f713beaa5907a776b8b3060cddd1c6ff0588554c2364698ae271321ce9",
      "nft": {
        "capability": "minting",
        "commitment": "f00fd00fb33f"
       }
    },
    "tx_hash": "87489c43bae69c297bbaf65276573b0001c20c647a3d54d2842a4425ff87bacc",
    "tx_pos": 1,
    "value": 1000000
  },
  {
    "height": 0,
    "tx_hash": "42f83727115dc7e38b1311aae9c516d9956c16f6017149c9d4a98cc5e738952a",
    "tx_pos": 7,
    "value": 99999815
  }
]

blockchain.scripthash.subscribe

Subscribe to a script hash.

Signature

.. function:: blockchain.scripthash.subscribe(scripthash)
.. versionadded:: 1.1
scripthash

The script hash as a hexadecimal string.

Result

The :ref:`status <status>` of the script hash.

Notifications

The client will receive a notification when the :ref:`status <status>` of the script hash changes. Its signature is
.. function:: blockchain.scripthash.subscribe(scripthash, status)
   :noindex:

blockchain.scripthash.unsubscribe

Unsubscribe from a script hash, preventing future notifications if its :ref:`status <status>` changes.

Signature

.. function:: blockchain.scripthash.unsubscribe(scripthash)
.. versionadded:: 1.4.2
scripthash

The script hash as a hexadecimal string.

Result

Returns :const:`true` if the scripthash was previously subscribed-to, otherwise :const:`false`. Note that :const:`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

.. function:: blockchain.transaction.broadcast(raw_tx)

.. versionchanged:: 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 :ref:`double-spend proof <dsproofs>`. The query can be by either tx_hash or dspid.

Signature

.. function:: blockchain.transaction.dsproof.get(hash)
.. versionadded:: 1.4.5
hash

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

Result

If the transaction in question has an associated :ref:`dsproof <dsproofs>`, then a JSON object. Otherwise :const:`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

.. function:: blockchain.transaction.dsproof.list()

.. versionadded:: 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 :func:`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 :ref:`dsproof <dsproofs>` notifications for a transaction.

Signature

.. function:: blockchain.transaction.dsproof.subscribe(tx_hash)
.. versionadded:: 1.4.5
tx_hash

The transaction hash as a hexadecimal string.

Result

A result identical to what one would get from :func:`blockchain.transaction.dsproof.get`.

Notifications

The client will receive a notification when the :ref:`dsproof <dsproofs>` status of the transaction changes. Its signature is
.. function:: blockchain.transction.dsproof.subscribe(tx_hash, dsproof)
   :noindex:

   With *dsproof* being identical to what one would get from invoking
   :func:`blockchain.transaction.dsproof.get` for that particular *tx_hash*.

blockchain.transaction.dsproof.unsubscribe

Unsubscribe from receiving any further :ref:`dsproof <dsproofs>` notifications for a transaction.

Signature

.. function:: blockchain.transaction.dsproof.unsubscribe(tx_hash)
.. versionadded:: 1.4.5
tx_hash

The transaction hash as a hexadecimal string.

Result

Returns :const:`true` if the transaction was previously subscribed-to for dsproof notifications, otherwise :const:`false`. Note that :const:`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

.. function:: blockchain.transaction.get(tx_hash, verbose=false)
.. versionchanged:: 1.1
   ignored argument *height* removed
.. versionchanged:: 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 :const:`false`:

The raw transaction as a hexadecimal string.

If verbose is :const:`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 :const:`false`:

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

When verbose is :const:`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_confirmed_blockhash

Returns the block hash of the block that contains a particular transaction.

Signature

.. function:: blockchain.transaction.get_confirmed_blockhash(tx_hash, include_header=false)
.. versionadded:: 1.5.2
tx_hash

The transaction hash as a hexadecimal string.

include_header

Whether to also return the block header in the results dictionary (default :const:`false` if unspecified).

Result

If this transaction is unknown or is in the mempool, a JSON-RPC error result will be returned. If the transaction is confirmed in a block, a dictionary will be returned with the following keys:

block_hash

The block hash as a hexadecimal string.

block_header (optional, only if :const:`include_header=true`)

The binary block header as a hexadecimal string.

block_height

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

Result Examples

{
  "block_hash": "0000000000000000000058ae65224f518d755d99afd512536c81dee2359dbcdb",
  "block_height": 816182
}

{
  "block_hash": "00000000000000000001522da9f02d2707dd91139f32a89d515e537384ecf2b1",
  "block_header": "00400020780506d9aeaf379e2c61f7e4b1c14c55dfb88c844581000000000000000000004818be123cf187c2eed198bc8eeed8b83c896d50b31948a625153c337a6c126aca454e65948104173ae18f28",
  "block_height": 816153
}

blockchain.transaction.get_height

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

Signature

.. function:: blockchain.transaction.get_height(tx_hash)
.. versionadded:: 1.4.5
tx_hash

The transaction hash as a hexadecimal string.

Result

Either a numeric value or :const:`null`.

Numeric values :const:`> 0`

The transaction is confirmed at this block height.

Numeric values :const:`== 0`

The transaction is not confirmed but is in the mempool.

:const:`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

.. function:: blockchain.transaction.get_merkle(tx_hash, [height])
.. versionchanged:: 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

.. function:: blockchain.transaction.id_from_pos(height, tx_pos, merkle=false)
.. versionadded:: 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 :const:`false`, the transaction hash as a hexadecimal string. If :const:`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 :const:`false`:

"fc12dfcb4723715a456c6984e298e00c479706067da81be969e8085544b0ba08"

When merkle is :const:`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

.. function:: blockchain.transaction.subscribe(tx_hash)
.. versionadded:: 1.4.5
tx_hash

The transaction hash as a hexadecimal string.

Result

A result identical to what one would get from :func:`blockchain.transaction.get_height`.

Notifications

The client will receive a notification when the confirmation status of the transaction changes. Its signature is
.. function:: blockchain.transction.subscribe(tx_hash, height)
   :noindex:

   With *height* being identical to what one would get from invoking :func:`blockchain.transaction.get_height`.

blockchain.transaction.unsubscribe

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

Signature

.. function:: blockchain.transaction.unsubscribe(tx_hash)
.. versionadded:: 1.4.5
tx_hash

The transaction hash as a hexadecimal string.

Result

Returns :const:`true` if the transaction was previously subscribed-to, otherwise :const:`false`. Note that :const:`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

.. function:: blockchain.utxo.get_info(tx_hash, out_n)
.. versionadded:: 1.4.4
.. versionchanged:: 1.5.0
   *token_data* may appear in the result object if the UTXO contains a :ref:`CashToken <cashtokens>` (BCH only)
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, :const:`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 :ref:`script hash <script hashes>` as a hexadecimal string.

token_data (optional, BCH only)

A dictionary encapsulating the :ref:`CashToken data <token_data>` for this output. This key will be missing from the dictionary if the unspent output does not have any token data on it.

value

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

Result Example

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

On 1.5.0 or above, for a token-containing output on BCH:

{
  "confirmed_height": 126184,
  "scripthash": "726205b2b758bd656b400cf5356fdec733528e93fc5f0a578592ab862539f327",
  "token_data": {
    "amount": "1000000",
    "category": "8fd6a2f713beaa5907a776b8b3060cddd1c6ff0588554c2364698ae271321ce9",
    "nft": {
      "capability": "minting",
      "commitment": "f00fd00fb33f"
    }
  },
  "value": 1000000
}

daemon.passthrough

Invokes an RPC method on the bitcoin daemon's own RPC server, and returns the result.

Signature

.. function:: daemon.passthrough(dictionary)
.. versionadded:: 1.5.2
dictionary

Unlike other Electrum Cash protocol methods, which accept a JSON-RPC array as positional arguments, this RPC requires a dictionary under the JSON-RPC :const:`"params"` key for the request. The contents of this dictionary is itself a nested JSON-RPC pseudo-request, of the form: :const:`{"method": "...", "params": [...]}`

Note

This method is not available by default on most servers and must be explicitly enabled by the server admin, since it allows for any client to call into the bitcoind RPC in an unrestricted fashion, which is not secure nor safe to do for a public network. It is only documented here for advanced usages of the server for private networks wishing to use this method.

Result

The JSON-RPC :const:`"result"` that was returned by the demon is sent back to the client verbatim.

Example

--> Client sends:
{
  "id": 1,
  "method": "daemon.passthrough",
  "params": {
    "method": "getdsproofscore",
    "params": [
      "d3aac244e46f4bc5e2140a07496a179624b42d12600bfeafc358154ec89a720c"
    ]
  }
}

<-- Client receives:
{
  "id": 1,
  "jsonrpc": "2.0",
  "result": 1.0
}

mempool.get_fee_histogram

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

Signature

.. function:: mempool.get_fee_histogram()

.. versionadded:: 1.2

Result

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

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

.. function:: server.add_peer(features)
.. versionadded:: 1.1
features

The same information that a call to the sender's :func:`server.features` RPC call would return.

Result

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

server.banner

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

Signature

.. function:: server.banner()

Result

A string.

Example Result

"Welcome to Fulcrum!"

server.donation_address

Return a server donation address.

Signature

.. function:: server.donation_address()

Result

A string.

Example Result

"1BWwXJH3q6PRsizBkSGm2Uw4Sz1urZ5sCj"

server.features

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

Signature

.. function:: server.features()

.. versionchanged:: 1.4.2
   *hosts* key is no longer required, but recommended.

.. versionchanged:: 1.4.5
   *dsproof* key added (optional).

.. versionchanged:: 1.5.0
   *cashtokens* key added (optional).

.. versionchanged:: 1.5.3
   *rpa* 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 :ref:`script hashing <script hashes>`. 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 :func:`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 :const:`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 :const:`null` if SSL connectivity is not provided.

tcp_port

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

ws_port

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

wss_port

An integer. Omit or set to :const:`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 :const:`true`, then the server has :ref:`double-spend proof <dsproofs>` support, and it supports the :const:`blockchain.transaction.dsproof.*` set of RPC methods. If this key is missing or :const:`false`, then the server does not support :ref:`dsproofs <dsproofs>`.

cashtokens

A boolean value. If present and set to :const:`true`, then the server has :ref:`CashToken <cashtokens>` support, and it may return additional :ref:`token_data <token_data>` in UTXO-related results from some of its RPC methods. If this key is missing or :const:`false`, then the server does not support :ref:`CashTokens <cashtokens>`.

rpa

An optional dictionary. If present and not :const:`null`, it indicates that the server supports the reusable payment address RPCs such as :func:`blockchain.rpa.get_history`. The keys in the dictionary have the following meanings:

history_block_limit

Server configured limit on the number of blocks one can request to scan in a single :func:`blockchain.rpa.get_history` (or deprecated :func:`blockchain.reusable.get_history`) RPC call. The server will not scan more blocks than this value for any individual request and results will be truncated to respect this limit.

max_history

Server configured limit on the maximum number of elements one can receive in one :func:`blockchain.rpa.get_history` (or deprecated :func:`blockchain.reusable.get_history`) RPC call. The server will not return a JSON array exceeding this number of items, and it may truncate results to this limit or return nothing at all for requests that would produce results exceeeding this limit.

prefix_bits

The number of bits that are indexed for :ref:`rpa_prefix <rpa prefix>` searching. Requests cannot specify an :ref:`rpa_prefix <rpa prefix>` with bit-length longer than this limit.

prefix_bits_min

The minimum number of bits that clients can specify when searching by prefix in calls such as :func:`blockchain.rpa.get_history`. Requests cannot specify an :ref:`rpa_prefix <rpa prefix>` with bit-length smaller than this value.

starting_height

The first block height which is indexed by this server for RPA-related RPC calls. Prefix searching of blocks before this height will always yield empty results.

Example Result

{
    "genesis_hash": "000000000933ea01ad0ee984209779baaec3ced90fa3f408719526f8d77f4943",
    "hosts": {"14.3.140.101": {"tcp_port": 51001, "ssl_port": 51002}},
    "protocol_max": "1.5.3",
    "protocol_min": "1.4",
    "pruning": null,
    "server_version": "Fulcrum 1.10.0",
    "hash_function": "sha256",
    "dsproof": true,
    "cashtokens": true,
    "rpa": {
        "history_block_limit": 60,
        "max_history": 125000,
        "prefix_bits": 16,
        "prefix_bits_min": 8,
        "starting_height" :825000
    }
}

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

.. function:: 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

.. function:: server.ping()

.. versionadded:: 1.2

Result

Returns :const:`null`.

server.version

Identify the client to the server and negotiate the protocol version. Only the first :func:`server.version` message is accepted.

Signature

.. function:: 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 4.2.12", ["1.4", "1.4.5"])

Example Result:

["Fulcrum 1.9.0", "1.4.5"]

Files

protocol-methods.rst

Latest commit

History

protocol-methods.rst

File metadata and controls

Protocol Methods

blockchain.address.get_balance

blockchain.address.get_first_use

blockchain.address.get_history

blockchain.address.get_mempool

blockchain.address.get_scripthash

blockchain.address.listunspent

blockchain.address.subscribe

blockchain.address.unsubscribe

blockchain.block.header

blockchain.block.headers

blockchain.estimatefee

blockchain.header.get

blockchain.headers.get_tip

blockchain.headers.subscribe

blockchain.headers.unsubscribe

blockchain.relayfee

blockchain.reusable.get_history

blockchain.reusable.get_mempool

blockchain.rpa.get_history

blockchain.rpa.get_mempool

blockchain.scripthash.get_balance

blockchain.scripthash.get_first_use

blockchain.scripthash.get_history

blockchain.scripthash.get_mempool

blockchain.scripthash.listunspent

blockchain.scripthash.subscribe

blockchain.scripthash.unsubscribe

blockchain.transaction.broadcast

blockchain.transaction.dsproof.get

blockchain.transaction.dsproof.list

blockchain.transaction.dsproof.subscribe

blockchain.transaction.dsproof.unsubscribe

blockchain.transaction.get

blockchain.transaction.get_confirmed_blockhash

blockchain.transaction.get_height

blockchain.transaction.get_merkle

blockchain.transaction.id_from_pos

blockchain.transaction.subscribe

blockchain.transaction.unsubscribe

blockchain.utxo.get_info

daemon.passthrough

mempool.get_fee_histogram

server.add_peer

server.banner

server.donation_address

server.features

server.peers.subscribe

server.ping

server.version