Open source GitHub repo: https://github.com/blocknative/sdk​
The SDK uses our API, which has rate limits. Please see Rate Limits for more details.
It should take less than 5 minutes to get going with the SDK.
Go to the Account page at https://explorer.blocknative.com/account and setup an account with an email address. You will receive an email to confirm your account.
You can read the Getting Started guide on the API Docs to get more information on how to set up an API Key for your purpose. API keys segment analytics data. Consider using different API keys for development, staging, and production releases.
npm install bnc-sdk
// For Node < v13 / CommonJS environmentsconst BlocknativeSdk = require('bnc-sdk');const WebSocket = require('ws');const Web3 = require('web3');​// OR​// For Node >= v13 / es module environmentsimport BlocknativeSdk from 'bnc-sdk'import Web3 from 'web3'import WebSocket from 'ws' // only neccessary in server environments​// create options objectconst options = {dappId: 'Your dappId here',networkId: 1,system: 'bitcoin' // optional, defaults to ethereumtransactionHandlers: [event => console.log(event.transaction)],ws: WebSocket // only neccessary in server environmentsname: 'Instance name here' // optional, use when running multiple instances}​// initialize and connect to the apiconst blocknative = new BlocknativeSdk(options)
Send a transaction using web3.js and get the transaction hash while its processing. Let the SDK know the hash and it will track its progress through the mempool and into a block.
// initialize web3const web3 = new Web3(window.ethereum)​// get current accountconst accounts = await web3.eth.getAccounts();const address = accounts[0];​// create transaction options objectconst txOptions = {from: address,to: "0x792ec62e6840bFcCEa00c669521F678CE1236705",value: "1000000"}​// initiate a transaction via web3.jsweb3.eth.sendTransaction(txOptions).on('transactionHash', hash => {// call with the transaction hash of the// transaction that you would like to receive status updates forconst { emitter } = blocknative.transaction(hash)​// listen to some eventsemitter.on('txPool', transaction => {console.log(`Sending ${transaction.value} wei to ${transaction.to}`)})​emitter.on('txConfirmed', transaction => {console.log('Transaction is confirmed!')})​// catch every other event that occurs and log itemitter.on('all', transaction => {console.log(`Transaction event: ${transaction.eventCode}`)})
See how to get started with the SDK in this screencast:
The following options object needs to be passed when initializing and connecting
const options = {dappId: String,system: String,networkId: Number,transactionHandlers: Array,ws: WebSocket,name: String,onopen: Function,onerror: Function,ondown: Function,onreopen: Function,onclose: Function}
Your unique API key that identifies your application. You can generate a dappId
by visiting the Blocknative account page and creating a free account.
The system that you would like to monitor transactions on. Currently bitcoin
and ethereum
are supported. Defaults to ethereum
if no value is passed in.
Valid Ethereum network ids:
1
Main Network
3
Ropsten Test Network
4
Rinkeby Test Network
5
Goerli Test Network
42
Kovan Test Network
100
xDai POA Network
Valid Bitcoin network ids:
1
Main Network
2
Testnet Network
An array of functions that will each be called once for every status update for every transaction that is associated with this connection on a watched address or a watched transaction.
const handleTransactionEvent = event => {const {transaction, // transaction objectemitterResult // data that is returned from the transaction event listener defined on the emitter} = eventconsole.log(transaction)}​const options = {// other optionstransactionHandlers: [handleTransactionEvent]}
See the Transaction Object section for more info on what is included in the transaction
parameter.
If you are running the sdk
in a server environment, there won't be a native WebSocket instance available for the sdk
to use, so you will need to pass one in. You can use any WebSocket library that you prefer as long as it correctly implements the WebSocket specifications. We recommend ws.
If you are running multiple instances of the sdk
on the same client, passing in a name property allows the sdk
to properly manage persistent state.
A function that is called once the WebSocket has successfully connected to the Blocknative backend infrastructure.
A function that is called for every error that happens within the SDK including WebSocket connection errors. The function is called with an error object with the following parameters:
message
: String
- The error message, describing what went wrong
error
: ErrorObject
- An error object if ine exist (for instance a WebSocket error)
transaction
: String
- The hash
or txid
passed to the call to transaction
that caused the error
account
: String
- The address
passed to the call to account
that caused the error
If this function is not passed in then error will be thrown.
A function that is called when the WebSocket connection has dropped. The SDK will automatically reconnect.
A function that is called once the WebSocket has successfully re-connected after dropping.
A function that is called when the WebSocket has successfully been destroyed.
Import and initialize the SDK with the configuration options described above for client and server environments.
import BlocknativeSdk from 'bnc-sdk'​// create options objectconst options = {dappId: 'Your dappId here',networkId: 1,transactionHandlers: [event => console.log(event.transaction)]}​// initialize and connect to the apiconst blocknative = new BlocknativeSdk(options)
// For Node < v13 / CommonJS environmentsconst BlocknativeSdk = require('bnc-sdk');const WebSocket = require('ws');​// OR​// For Node >= v13 / es module environmentsimport BlocknativeSdk from 'bnc-sdk'import WebSocket from 'ws' // only neccessary in server environments​// create options objectconst options = {dappId: 'Your dappId here',networkId: 1,transactionHandlers: [event => console.log(event.transaction)],ws: WebSocket}​// initialize and connect to the apiconst blocknative = new BlocknativeSdk(options)
Now that your application is successfully connected via a WebSocket connection to the Blocknative back-end, you can register transactions to watch for updates (notifications).
Once you have initiated a transaction and have received the transaction hash, you can pass it in to the transaction
function:
// initiate a transaction via web3.jsweb3.eth.sendTransaction(txOptions).on('transactionHash', hash => {// call with the transaction hash of the transaction that you would like to receive status updates forconst {emitter, // emitter object to listen for status updatesdetails // initial transaction details which are useful for internal tracking: hash, timestamp, eventCode} = blocknative.transaction(hash)})​​
The emitter
is used to listen for status updates. See the Emitter Section for details on how to use the emitter
object to handle specific transaction state changes.
The details
object contains the initial transaction details which are useful for internal tracking.
If the library was initialized with transaction handlers, those handlers will also be called on each status change for the watched transaction.
If a transaction is watched that is currently in the txpool or was updated in the last 60 minutes, the SDK will immediately send a notification with the last detected status for that transaction.
If a watched transaction is replaced (status speedup or cancel), the SDK will automatically watch the hash of the replacement transaction for the client and start delivering notifications for it.
const { emitter, details } = blocknative.transaction(txid)
You can also register an account address to listen to any incoming and outgoing transactions that occur on that address using the account
method:
// get the current accounts list of the user via web3.jsconst accounts = await web3.eth.getAccounts()​// grab the primary accountconst address = accounts[0]​// call with the address of the account that you would like to receive status updates forconst {emitter, // emitter object to listen for status updatesdetails // initial account details which are useful for internal tracking: address} = blocknative.account(address)
This will tell the Blocknative back-end to watch for any transactions that occur involving this address and any updates to the transaction status over time. The return object from successful calls to account
will include an event emitter
that you can use to listen for those events and a details object which includes the address
that is being watched.
const { emitter, details } = blocknative.account(address)
If you no longer want to receive notifications for an account address or transaction hash, you can use the unsubscribe
method:
// unsubscribe from addressblocknative.unsubscribe(address)​// unsubscribe from Ethereum transaction hashblocknative.unsubscribe(hash)​// unsubscribe from Bitcoin txidblocknative.unsubscribe(txid)
You may want to log an event that isn't associated with a transaction for analytics purposes. Events are collated and displayed in the developer portal and are segmented by your dappId
. To log an event, simple call event
with a categoryCode
and an eventCode
, both of which can be any String
that you like:
blocknative.event({categoryCode: String, // [REQUIRED] - The general category of the eventeventCode: String // [REQUIRED] - The specific event})
The emitter object is returned from calls to account
and transaction
and is used to listen to status updates via callbacks registered for specific event codes.
// register a callback for a txPool eventemitter.on("txPool", transaction => {console.log("Transaction is pending")})
The first parameter is the eventCode
string of the event that you would like to register a callback for. For a list of the valid event codes, see the event codes section.
The second parameter is the callback that you would like to register to handle that event and will be called with a transaction object that includes all of the relevant details for that transaction. See the Transaction Object section for more info on what is included.
Any data that is returned from the listener callback for transaction
emitters will be included in the object that the global transactionHandlers
are called with under the emitterResult
property.
To prevent memory leaks on long running processes, you can use the off
method on the emitter to remove your callback listener:
// remove callback for txPool eventemitter.off('txPool')
The callback that is registered for events on an emitter or included in the transactionHandlers
array will be called with the following transaction object:
{status: String, // current status of the transactionhash: String,to: String,from: String,gas: Number,gasPrice: String,gasUsed: String, // present on on-chain txnsnonce: Number,value: String,eventCode: String,blockHash: String,blockNumber: Number,input: String,timeStamp: string // the UTC time of first detection of current statuspendingTimeStamp: string // the UTC time of initial pending status detectionpendingBlockNumber: Number // the chain head block number at time of pending detectiontransactionIndex: Number, // optional, present if status confirmed, failedblockTimeStamp: String, // optional, present if status confirmed, failed - UTC time of miner block creationcounterParty: String, // address of the counterparty of the transaction when watching an accountdirection: String, // the direction of the transaction in relation to the account that is being watched ("incoming" or "outgoing")watchedAddress: String, // the address of the account being watchedtimePending: String, // optional, present if status confirmed, failed, speedup, cancelblocksPending: Number, // optional, present if status confirmed, failed, speedup, canceloriginalHash: String, // if a speedup or cancel status, this will be the hash of the original transactionasset: String, // the asset that was transferedcontractCall: { // if transaction was a contract call otherwise undefinedcontractAddress: String,contractType: String,methodName: String,params: {// params that the contract method was called with},contractName: String,contractDecimals: Number (optional),decimalValue: String (optional),}}
{"rawTransaction": {"txid": String,"hash": String,"version": Number,"size": Number,"vsize": Number,"weight": Number,"locktime": Number,"vin": Vin[],"vout": Vout[],"hex": String,},"txid": String,"system": String,"network": String,"status": Status,"apiKey": String,"monitorVersion": String,"monitorId": String,"serverVersion": String,"timeStamp": String,"timePending": String,"watchedAddress": String,"inputs": Transfer[],"outputs": Transfer[],"fee": String,"netBalanceChanges": BalanceChange[],"blockHeight": String,"blockHash": String,}​// Vin{"txid": String,"vout": Number,"scriptSig": {"asm": String,"hex": String},"txinwitness": String[],"sequence": Number}​// Vout{"value": Number,"n": Number,"scriptPubKey": {"asm": String,"hex": String,"reqSigs": Number,"type": String,"addresses": String[]}}​// Transfer{"address": String,"value": String}​// BalanceChange{"address": String,"delta": String}
The SDK will send confirmed
notifications when a watchedAddress
is detected in the internal transactions of a contract call. In this case, the confirmed
transaction object will include details of the internal transactions and balance changes resulting from those internal transactions. Fields are not ordered.
"internalTransactions": [],"netBalanceChanges": Object
Field | Description |
| Array of objects containing details of each internal transaction (see below) |
| Object containing details of balance changes for all addresses involved in internal transactions (see below) |
The internalTransactions
array contains details on each internal transaction executed by the contract call of the parent (main) transaction. Fields are not ordered.
"internalTransactions": [{"type": String,"from": String,"to": String,"input": String,"gas": Number,"gasUsed": Number,"value": String,"contractCall": Object (optional, contains an additional param 'contractAlias' which will be the symbol of the token if this is an erc20 transfer or transferFrom)},...]
Field | Description |
| Type of internal transaction (one of |
| Address initiating the internal transaction call (typically the parent (main) transaction's contract address |
| Address the internal transaction is calling or sending value to |
| Data sent to internal transaction. For value transfers from external account initiating parent (main) transaction to another external account, this field contains |
| Maximum amount of gas available to the internal transaction |
| Amount of gas actually used executing the internal transaction |
| Amount of ETH transferred directly to |
| Optional. A series of keys and values specific to the contract method . This object is present only if the contract method call includes parameters and Blocknative decodes the internal transaction contract call (e.g. an ERC20 transfer). For details see decoded contract payload above.
NOTE: If the Internal transaction is an ERC20 |
The netBalanceChanges
object contains details of all the balance changes resulting from the internal transactions details in the internalTransactions
array.
"netBalanceChanges": {"<address>": [{"delta": String,"asset": {"type": String,"symbol": String},"breakdown": [{"counterparty": Atring,"amount": String}]}],...}
Field | Description |
| Address involved in internal transaction. Each address contains an array of balances changes, one for each |
| Details of the asset being transferred. Contains |
| Amount of value transfer (balance change) in wei to the |
| The type of asset transferred (e.g. "ether") |
| The symbol of the asset transferred. "ETH" or appropriate ERC20 symbol |
| Array of individual transfers to |
| Address of the other side of the transfer relative to the |
| The amount of asset transferred with this |
The following is a list of event codes that are valid, and the events that they represent:
all
: Will be called for all events that are associated with that emitter. If a more specific listener exists for that event, then that will be called instead. This is useful to catch any remaining events that you haven't specified a handler for
txSent
: Transaction has been sent to the network
txPool
: Transaction was detected in the "pending" area of the mempool and is eligible for inclusion in a block
txStuck
: Transaction was detected in the "queued" area of the mempool and is not eligible for inclusion in a block
txConfirmed
: Transaction has been mined
txFailed
: Transaction has failed
txSpeedUp
: A new transaction has been submitted with the same nonce and a higher gas price, replacing the original transaction
txCancel
: A new transaction has been submitted with the same nonce, a higher gas price, a value of zero and sent to an external address (not a contract)
txDropped
: Transaction was dropped from the mempool without being added to a block
You may want to filter events that occur on an Ethereum address and/or have the Blocknative server automatically decode the input data for a particular contract. To do this the configuration
function can be used to send a configuration that will be scoped globally or to a particular address:
await blocknative.configuration({scope: String, // [required] - either 'global' or valid Ethereum addressfilters: Array, // [optional] - array of valid searchjs filter stringsabi: Array, // [optional] - valid contract ABIwatchAddress: Boolean // [optional] - Whether the server should automatically watch the "scope" value if it is an address})​// returns a promise that resolves once the configuration has been applied// or rejects if there was a problem with the configuration
scope
- [required]
The scope that the configuration will be applied to. Can be a 'global'
configuration so that you can filter all events for all addresses that you are watching or a valid Ethereum address to scope the configuration to events that occur only on that address.
filters
- [optional]
The filters that you would like applied to events in scope. The Blocknative server uses jsql
a JavaScript query language to filter events. Documentation for how to create filter queries can be found here​
abi
- [optional]
A JavaScript ABI (application binary interface) so that the Blocknative server can automatically decode transaction input data
watchAddress - [optional]
If the scope
is an Ethereum address, then watchAddress
can be set to true so that the Blocknative server can automatically watch the address in scope, rather than needing to send an extra call to blocknative.account
You can download a Mempool Explorer configuration to be used with the SDK. You can also use your account page to download a configuration that was saved to a specific API key. Once you have the files (configuration.json
, sdk-setup.js
) downloaded, drop them in to your project directory. They can then be imported and setup with the SDK:
import BlocknativeSDK from 'bnc-sdk'import configuration from './configuration'import sdkSetup from './sdk-setup'​// function to handle all transaction eventsfunction handleTransactionEvent(transaction) {console.log('Transaction event:', transaction)}​// initialize the SDKconst blocknative = BlocknativeSDK({// ...other initialization optionstransactionHandlers: [handleTransactionEvent]})​// setup the configuration with the SDKsdkSetup(blocknative, configuration)
Sign up for a free Blocknative Account at https://account.blocknative.com/ with your work email address.
If you have any questions, connect with the team on our discord​