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Digital Assets

Version 1.0.0

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The storing of Digital Assets such as ONT and ONG is handled by the Java SDK using the Account structure, which is outlined below.

Data structure

address Base58 encoded account address

label Name of account

isDefaultIndicates whether the account is the default

lock Indicates whether the account is locked by the client user - Locked accounts can’t spend

algorithm Name of the encryption algorithm used

parameters Encryption parameters

curve Elliptic curve used

key NEP-2 private key - whose value can be null in case of read-only or non-standard addresses

contract Smart contract hash - whose value can be null in case of read-only addresses

encAlg Private key encryption algorithm name - fixed at aes-256-ctr

salt Private key decryption salt

extra Extra information stored by client developer - value can be null

signatureScheme signatureScheme Signature scheme used for transaction signatures

hash Hash algorithm for derived privateKey

Example Account class:

public class Account {
    public String label = "";
    public String address = "";
    public boolean isDefault = false;
    public boolean lock = false;
    public String algorithm = "";
    public Map parameters = new HashMap() ;
    public String key = "";
    @JSONField(name = "enc-alg")
    public String encAlg = "aes-256-gcm";
    public String salt = "";
    public String hash = "sha256";
    public String signatureScheme = "SHA256withECDSA";
    public Object extra = null;
}

Digital asset account management

The following code shows some common digital asset functions:

Create digital asset account

OntSdk ontSdk = OntSdk.getInstance();
Account acct = ontSdk.getWalletMgr().createAccount("password");
//any account or identity, once created is stored in memory only. A write api should be invoked to write to a wallet file.
ontSdk.getWalletMgr().writeWallet();

Remove digital asset account

ontSdk.getWalletMgr().getWallet().removeAccount(address);
//write to wallet
ontSdk.getWalletMgr().writeWallet();

Set default digital asset account

ontSdk.getWalletMgr().getWallet().setDefaultAccount(index);
ontSdk.getWalletMgr().getWallet().setDefaultAccount("address");

Note:

index: The account with such index number is set as the default account.
address: The account with such address is set as the default account. —-

Native digital asset methods

Methods apply to both ONT and ONG assets.

sendTransfer

String sendTransfer (Account sendAcct, String recvAddr, long amount, Account payerAcct, long gaslimit, long gasprice)

Function description: Transfer a certain amount of assets from the sender to the receiver’s account.

Parameters:

sendAcct: Sender account

recvAddr: Receiver address

amount: Asset amount

payerAcct: Payment transaction account

gaslimit: Gas limit

gasprice: Gas price

return value: Transaction hash

sendApprove

String sendApprove (Account sendAcct, String recvAddr, long amount, Account payerAcct, long gaslimit, long gasprice)

Function description: SendAcct account allows recvAddr to transfer amount of assets.

Parameters:

sendAcct: Sender account

recvAddr: Receive address

amount: Asset amount

payerAcct: Payment transaction account

gaslimit: Gas limit

gasprice: Gas price

return value: Transaction hash

sendTransferFrom

 String sendTransferFrom (Account sendAcct, String fromAddr, String toAddr, long amount, Account payerAcct, long gaslimit, long gasprice)

Function description: The sendAcct account transfers the amount of assets from the fromAddr account to the toAddr account.

Parameters:

sendAcct: Sender account

fromAddr: From address

toAddr: Receive address

amount: Asset amount

payerAcct: Payment transaction account

gaslimit: Gas limit

gasprice: Gas price

return value: Transaction hash

queryBalanceOf

 long queryBalanceOf (String address)

Function description: Query the asset balance of the account address.

Parameters: address：Account address

return value： Balance of address

queryAllowance

long queryAllowance (String fromAddr,String toAddr)

Function description: Query balance of the account address.

Parameters:

fromAddr: From address

toAddr: To address

return value: Asset amount

queryName

String queryName()

Function description: Query asset name information.

return value: Asset name detail information

querySymbol

String querySymbol

Function description: Query asset symbol information.

return value：Symbol information

queryDecimals

  long queryDecimals()

Function description: Query the accuracy of assets

return value：decimal

queryTotalSupply

long queryTotalSupply()

Function description： Query the total supply of assets

return value：total Supply

Example:

//get sdk instance
OntSdk sdk = OntSdk.getInstance();
sdk.setRpc(url);
sdk.openWalletFile("OntAssetDemo.json");
//get ontAssetTx instance
ont = sdk.nativevm().ont()
//transfer
com.github.ontio.account.Account account1 = new com.github.ontio.account.Account(privateKey,SignatureScheme.SHA256WITHECDSA);
ont.sendTransfer(account1,"TA4pCAb4zUifHyxSx32dZRjTrnXtxEWKZr",10000,account1,ontSdk.DEFAULT_GAS_LIMIT,0);

NEP-5 smart contract digital assets

NEP-5 document：

https://github.com/neo-project/proposals/blob/master/nep-5.mediawiki

Digital assets template:

https://github.com/neo-project/examples/tree/master/ICO_Template

Function	Params	Returns	Description
sendInit	boolean preExec	String	If true, it indicates that the pre-execution is to test whether it has been initialized. If it is false, the contract parameters are initialized.
sendTransfer	String sendAddr, String password, String recvAddr, int amount	String	Transfer assets
sendBalanceOf	String addr	String	Get account balance
sendTotalSupply		String	Get total supply
sendName		String	Get name
sendDecimals		String	Get accuracy
sendSymbol		String	Query token abbreviation

NEP-5 smart contract template

using Neo.SmartContract.Framework;
using Neo.SmartContract.Framework.Services.Neo;
using Neo.SmartContract.Framework.Services.System;
using System;
using System.ComponentModel;
using System.Numerics;

namespace Nep5Template
{
    public class Nep5Template : SmartContract
    {
        //Token Settings
        public static string Name() => "Nep5Template Token";
        public static string Symbol() => "TMP";
        public static readonly byte[] community = "AXK2KtCfcJnSMyRzSwTuwTKgNrtx5aXfFX".ToScriptHash();
        public static byte Decimals() => 8;
        private const ulong factor = 100000000; //decided by Decimals()

        //ICO Settings
        private const ulong totalAmount = 1000000000 * factor;
        private const ulong communityCap = 1000000000 * factor;

        [DisplayName("transfer")]
        public static event Action<byte[], byte[], BigInteger> Transferred;

        public static Object Main(string operation, params object[] args)
        {
            if (Runtime.Trigger == TriggerType.Application)
            {
                if (operation == "init") return Init();
                if (operation == "totalSupply") return TotalSupply();
                if (operation == "name") return Name();
                if (operation == "symbol") return Symbol();
                if (operation == "transfer")
                {
                    if (args.Length != 3) return false;
                    byte[] from = (byte[])args[0];
                    byte[] to = (byte[])args[1];
                    BigInteger value = (BigInteger)args[2];
                    return Transfer(from, to, value);
                }
                if (operation == "balanceOf")
                {
                    if (args.Length != 1) return 0;
                    byte[] account = (byte[])args[0];
                    return BalanceOf(account);
                }
                if (operation == "decimals") return Decimals();
            }
            return false;
        }

        // init
        public static bool Init()
        {
            byte[] total_supply = Storage.Get(Storage.CurrentContext, "totalSupply");
            if (total_supply.Length != 0) return false;

            Storage.Put(Storage.CurrentContext, community, communityCap);
            Transferred(null, community, communityCap);

            Storage.Put(Storage.CurrentContext, "totalSupply", totalAmount);
            return true;
        }

        // get the total token supply
        // Get the total number of issued tokens
        public static BigInteger TotalSupply()
        {
            Runtime.CheckSig(new byte[1]{ 1 },  new byte[]{2},new byte[]{ 3});
            return Storage.Get(Storage.CurrentContext, "totalSupply").AsBigInteger();
        }

        // function that is always called when someone wants to transfer tokens.
        // transfer token
        public static bool Transfer(byte[] from, byte[] to, BigInteger value)
        {
            if (value <= 0) return false;
            if (!Runtime.CheckWitness(from)) return false;
            if (from == to) return true;
            BigInteger from_value = Storage.Get(Storage.CurrentContext, from).AsBigInteger();
            if (from_value < value) return false;
            if (from_value == value)
                Storage.Delete(Storage.CurrentContext, from);
            else
                Storage.Put(Storage.CurrentContext, from, from_value - value);
            BigInteger to_value = Storage.Get(Storage.CurrentContext, to).AsBigInteger();
            Storage.Put(Storage.CurrentContext, to, to_value + value);
            Transferred(from, to, value);
            return true;
        }

        // get the account balance of another account with address
        // Get the token's balance based on the address
        public static BigInteger BalanceOf(byte[] address)
        {
            return Storage.Get(Storage.CurrentContext, address).AsBigInteger();
        }
    }
}