In this slightly more complex but still essential and though basic example we send some Signa to another account. Now, we need to get the senders passphrase to generate the keys we need for signing the transaction. The example assumes that we gathered the information somehow before. To see how to do this interactively in the command line we recommend our working examples in the repository.
A fully working example is available
The SignumJS library uses a local signing concept for advanced security. That means that under absolutely no circumstances no passphrase or private key is sent over the network.
Following functions from SignumJS are used in this example
/**
* A small helper function that returns the api object
*/
function provideLedger(nodeHost) {
const ledger = composeApi({
nodeHost
});
console.info('-------------------------------------------');
console.info(`The selected Signum Node is node is: ${ledger.service.settings.nodeHost}`);
console.info('-------------------------------------------');
return ledger
}
// some preset networks
const LedgerHostUrls = {
'TestNet': 'http://localhost:6876',
'MainNet': 'https://europe.signum.network',
}
/**
* This example shows how to send some amount of SIGNA to another account
*/
async function sendSigna(args) {
try {
const {ledgerType, recipient, amount, feeType} = args
// actually, the provided ledger is the Api object returned from composeApi
// we assume that the values are ['TestNet', 'MainNet']
const ledger = provideLedger(LedgerHostUrls[ledgerType])
// we check if incoming account is either a Signum Address, or Numeric Id
// eventually, we convert to Numeric Id, if the value is invalid an error will be thrown
const recipientId = Address.create(recipient).getNumericId()
// now we check if the account exists. If it does not exist the method throws an
// exception and the further flow is interrupted.
// Using exception to assert certain conditions is IMHO more robust than checking returned
// values with if-statements. The code is much cleaner
console.info("Verifying recipient...")
await ledger.account.getAccount({accountId: recipientId})
// before we can send we need to get the private signing key from the user
// In this current scenario we ask the user for his passphrase, as we can then derive the necessary key
// this is an external function not related to SignumJS - it's here for demonstratopion purposes
const {passphrase} = await confirmTransaction(args)
// once we gathered the passphrase, we can generate the signing keys
const {publicKey, signPrivateKey} = generateMasterKeys(passphrase)
// as a next step, we use the systems fee suggestion mechanism to give us the current costs for the chosen
// fee type. In this example we let it flexible, but you can fix the fee costs to a minimum, i.e. 0,00735 SIGNA
const suggestedFees = await ledger.network.getSuggestedFees()
// we assume that the feeType is either ['Minimum', 'Cheap', 'Standard', 'Priority']
const selectedFeePlanck = suggestedFees[feeType.toLowerCase()]
// Now, we execute the transaction
// within this method the local signing flow is being executed, i.e.
// the private key is used only locally for signinh, but never sent over the network
const {transaction} = await ledger.transaction.sendAmountToSingleRecipient(
{
recipientId,
amountPlanck: Amount.fromSigna(amount).getPlanck(),
feePlanck: selectedFeePlanck,
senderPrivateKey: signPrivateKey,
senderPublicKey: publicKey
}
);
// now, some final nice message
const addressPrefix = ledgerType === 'MainNet' ? AddressPrefix.MainNet : AddressPrefix.TestNet
console.info(`Successfully sent ${amount} ${CurrencySymbol} to ${Address.create(recipientId, addressPrefix).getReedSolomonAddress()} - Transaction Id: ${transaction}`)
console.info(`You paid a total of ${Amount.fromSigna(amount).add(Amount.fromPlanck(selectedFeePlanck)).toString()}`)
} catch (e) {
handleError(e);
}
}
// TO DO
function to create the api instance (the method is called inside provideLedger)
method to send some Signa to a single recipient
method to fetch current base fees
method to fetch details of an account
Value Object to parse and convert the given address
Value Object to convert between Planck and Signa
Essential cryptographic function to derive the cryptographic keys for signing transactions from a passphrase
