XChainPy Wallet Client Interface

A specification for a generalised interface for crypto wallets clients, to be used by XChainPy implementations. The client should not have any functionality to generate a key, instead, the asgardex-crypto library should be used to ensure cross-chain compatible keystores are handled. The client is only ever passed a master BIP39 phrase, from which a temporary key and address is decoded.

Configuration

Initialise and set up the client to connect to its necessary third-party services to fulfil basic functionality. The third-party services used must be at a minimum to fulfil the wallet functionality, such as displaying balances and sending transactions.

During configuration, the following can be passed in:

• Network choice (default is TESTNET)
• Phrase (mandatory)
• Service Keys (optional, if null, client will use config defaults or free service limits.)

Querying

Querying the client for balances and transaction history. Transaction history is optional.

Optional blockchain-specific queries can be added here, such as Binance Chain market information.

Transactions

Making transfers.

Optional blockchain-specific transactions can be added here, such as Binance Chain freeze/unfreeze.

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Class Variables

Client

Client Implementation

class client(IXChainClient) 

Network

Network types are 'mainnet' and 'testnet' strings

Address

Public variable that returns the address decoded from the private key during initialisation. type of address is str

Config and Setup

Set Network

Used to set a type of Network, which is either 'mainnet' or 'testnet'.

set_network(net:str)

Set Phrase

Used to set the master BIP39 phrase, from which the private key is extracted and the address decoded.

set_phrase(phrase:str) -> str

The function should store the private key and address, then return the address generated by the phrase.

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Querying

Get Explorer URLs

Returns the correctly formatted url string with paths for:

• Addresses
• Transactions

The default Explorer URL can be hard-coded, or passed in as a service. It will be provided by get_explorer_url

get_explorer_url() -> str

To get explorer's URL for an address, use get_explorer_address_url by passing an address.

get_explorer_address_url = (address:str) -> str

To get explorer's URL for a transaction, use get_explorer_tx_url by passing a transaction ID.

get_explorer_tx_url = (tx_id:str) -> str

All functions should return the correctly formatted url string.

Example

https://blockchair.com/bitcoin/transaction/d11ff3352c50b1f5c8e2030711702a2071ca0e65457b40e6e0bcbea99e5dc82e
https://blockchair.com/bitcoin/address/19iqYbeATe4RxghQZJnYVFU4mjUUu76EA6

https://explorer.binance.org/tx/94F3A6257337052B04F9CC09F657966BFBD88546CA5C23F47AB0A601D29D8979
https://explorer.binance.org/address/bnb1z35wusfv8twfele77vddclka9z84ugywug48gn

https://etherscan.io/tx/0x87a4fa498cc48874631eaa776e84a49d28f42f01e22c51ff7cdfe1f2f6772f67
https://etherscan.io/address/0x8eb68e8f207be3dd1ec4baedf0b5c22245cda463

Get Balance

Returns the balance of an address.

• If address is not passed, gets the balance of the current client address.
• Optional asset can be passed, in which the query will be specific to that asset, such as ERC-20 token.
• Returns an array of assets and amounts, with assets in chain notation CHAIN.SYMBOL-ID

Balance model :

get_balance(address:str=None, asset:str=None) -> Balance

Example of third-party service queries to get balances:

https://sochain.com/api/v2/get_address_balance/BTCTEST/tb1q2pkall6rf6v6j0cvpady05xhy37erndvku08wp
https://api.ethplorer.io/getAddressInfo/0xb00E81207bcDA63c9E290E0b748252418818c869?apiKey=freekey
https://dex.binance.org/api/v1/account/bnb1jxfh2g85q3v0tdq56fnevx6xcxtcnhtsmcu64m

Example of returned array:

[
   {   # xchainpy_client.models.balance.Balance
      asset: {  # xchainpy_util.asset.Asset
         chain: "BNB",
         symbol: "BNB",
         ticker: "BNB"
      },
      amount: 100000000
   }
]

Get Transactions

Gets a simplied array of recent transactions for an address.

# Defined in xchainpy_client/models/tx_types.py
 class TxHistoryParams:
    def __init__(self, address:str, offset:int=None, limit:int=None, start_time=None, asset:Asset=None):
        self._address = address
        self._offset = offset
        self._limit = limit
        self._start_time = start_time
        self._asset = asset


get_transactions(params:TxHistoryParams) -> xchainpy_client.models.tx_types.TxPage

Example of third party services to help:

// get UTXOS for address
https://sochain.com/api/v2/get_tx_unspent/BTC/34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo
// get tx details
https://sochain.com/api/v2/get_tx/BTC/ff0bd969cce99b8d8086e452d7b63167fc178680fee796fc742cb14a9a6ef929

https://api.ethplorer.io/getAddressTransactions/0xb297cacf0f91c86dd9d2fb47c6d12783121ab780?apiKey=freekey
https://dex.binance.org/api/v1/transactions?address=bnb1jxfh2g85q3v0tdq56fnevx6xcxtcnhtsmcu64m

Example of return:

[ # xchainpy_client.models.tx_types.TxPage
    total: 1,
    txs: [
        {  # # xchainpy_client.models.tx_types.TX
        tx_hash: "980D9519CCB39DC02F8B0208A4D181125EE8A2678B280AF70666288B62957DAE",
        tx_from: [ # xchainpy_client.models.tx_types.TxFrom
            {
                address: "tbnb1t95kjgmjc045l2a728z02textadd98yt339jk7",
                amount: 100
            }
        ],
        tx_to: [ # xchainpy_client.models.tx_types.TxTo
            {
                address: "tbnb1t95kjgmjc045l2a728z02textadd98yt339jk7",
                amount: 100
            }
        ],
        tx_amount: 100,
        tx_fee: 2500,
        tx_memo: "transfer"
        tx_date: datetime.datetime(2021, 8, 2, 12, 50, 10, 407000),
        asset: {  # xchainpy_util.asset.Asset
             chain: "BNB",
             symbol: "BNB",
             ticker: "BNB"
        },
       }
    ]
]

Due to the complexity of this function and dependence of third-party services, this function can be omitted in early versions of the client.

---

Transactions

Get Fees

This function calculates and returns the fee object in a generalised way for a simple transfer function.

Since this depends on optional third-party services, sensible defaults should be hardcoded if there are errors.

The fastest fee rate should be guaranteed next block (1.5x Fast), fast should be 1-2 blocks (1x next block fee rate), average should be 2-3 blocks (0.5x Fast). Don't over-complicate this. PoW blockchains have no guarantees.

• Type should specify the units to display, or if flat fees, simply "flat". The client should interpret and display this, such as showing the user the fee rates and their units.
• Fastest (target of next block)
• Fast (target of 1-2 blocks)
• Average (target of 2-3 blocks)

Third party services: Bitcoin - returns next block feeRate (fast). Use multiples of this to extrapolate to Fastest/Average. https://api.blockchair.com/bitcoin/stats

Ethereum - returns fastest/fast/average https://ethgasstation.info/api/ethgasAPI.json?api-key=XXAPI_Key_HereXXX

get_fees() -> xchainpy_client.models.types.Fees

Example

# Binance Chain
{ # xchainpy_client.models.types.Fees
  fastest : 0.0001125
  fast : 0.0001125
  average : 0.0001125
}

Transfer

General transfer function that should be signed and broadcast using a third party service. The fee should always be rate, which is units per transaction size. The size should be calculated on the fly or hardcoded:

• Bitcoin: 250 bytes is typical, so feeRate of 10 is 10 sats per byte, eg, 2500 sats
• Ethereum: gwei is standard, so a feeRate of 20 would be interpreted as 20 GWEI
• Binance Chain: fixed size, so the feeRate is ignored.

Broadcast URLs

https://api.blockchair.com/{:chain}/push/transaction
https://dex.binance.org/api/v1/broadcast

class TxParams:
    def __init__(self, asset:Asset, amount, recipient, memo='', wallet_index=None):
        self._asset = asset
        self._amount = amount
        self._recipient = recipient
        self._memo = memo
        self._wallet_index = wallet_index

transfer(params:tx_types.TxParams) -> str

The function should return the hash of the finalised transaction.

Purge

When a wallet is "locked" the private key should be purged in each client by setting it back to null. Also the phrase has to be cleared self.phrase = ''

purge_client()