![function approve(address _spender, uint256 _value) public returns (bool) {
allowed[msg.sender][_spender] = _value;
emit Approval(msg.sender, _spender, _value);
return true;
}
function allowance(
address _owner,
address _spender
)
public view returns (uint256)
{
return allowed[_owner][_spender];
}
function increaseApproval(
address _spender,
uint _addedValue
)
public
returns (bool)
{
allowed[msg.sender][_spender] = (
allowed[msg.sender][_spender].add(_addedValue));
emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
return true;
}
pragma solidity ^0.4.23;
contract StandardToken is ERC20, BasicToken {
mapping (address => mapping (address => uint256)) internal allowed;
function transferFrom(
address _from,
address _to,
uint256 _value
)
public
returns (bool)
{
require(_to != address(0));
require(_value <= balances[_from]);
require(_value <= allowed[_from][msg.sender]);
balances[_from] = balances[_from].sub(_value);
balances[_to] = balances[_to].add(_value);
allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
emit Transfer(_from, _to, _value);
return true;
}
Smart Contract in Solidity](https://image.slidesharecdn.com/tokenplatformbasedonsidechain-180918143745/85/Token-platform-based-on-sidechain-8-320.jpg)
Token platform based on sidechain
- 1. Token Platform based on Sidechain
- 2. Index 1. Decentralized Token Economy on Application 2. Challenges 3. Challenges - Evolutions 4. Luniverse Blockchain Service Platform 5. Future Works
- 3. Decentralized Token Economy on Application
- 5. ▪ October 2017 • # of ERC20 Tokens : 10,565 ▪ September 2018 • # of ERC20 Tokens : 116,741 (https://etherscan.io/tokens) Ethereum ERC20 Tokens
- 6. Token Economy on Application REST API REST Server Database REST API REST Server Database web3.js SmartContract
- 7. Steps for Applying Token Economy Contract Development ● Develop Token Contract ● Develop Crowd Sale Contract ● ... Private Blockchain Construction ● Construct Private Blockchain Network ● Deploy Private Blockchain Network Application Development ● Write and Test DApp ● Deploy DApp ● Write Business Logic in Smart Contract ● Solidity ● Truffle ● Web3.js ● Blockchain ● Cloud Platform ( AWS, Azure, …) ● Infrastructure Management ● Solidity ● Web3.js ● Truffle ● Metamask Deployment & Operation ● Manage Private Blockchain Network ● Deploy / Monitor / Shutdown / Recover ● Manage Private Keys ● Cloud Platform (AWS, Azure, …) ● Kubernetes, Ansible ● Truffle
- 8. function approve(address _spender, uint256 _value) public returns (bool) { allowed[msg.sender][_spender] = _value; emit Approval(msg.sender, _spender, _value); return true; } function allowance( address _owner, address _spender ) public view returns (uint256) { return allowed[_owner][_spender]; } function increaseApproval( address _spender, uint _addedValue ) public returns (bool) { allowed[msg.sender][_spender] = ( allowed[msg.sender][_spender].add(_addedValue)); emit Approval(msg.sender, _spender, allowed[msg.sender][_spender]); return true; } pragma solidity ^0.4.23; contract StandardToken is ERC20, BasicToken { mapping (address => mapping (address => uint256)) internal allowed; function transferFrom( address _from, address _to, uint256 _value ) public returns (bool) { require(_to != address(0)); require(_value <= balances[_from]); require(_value <= allowed[_from][msg.sender]); balances[_from] = balances[_from].sub(_value); balances[_to] = balances[_to].add(_value); allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value); emit Transfer(_from, _to, _value); return true; } Smart Contract in Solidity
- 9. DApp in web3.js async function deployContract(web3, abi, bin, contractParams, transactionParams) { return new Promise((resolve, reject) => { // create a contract from ABI createContract(web3, abi) .then(async function(contractObject) { // deploy the created contract const deploy = contractObject.deploy({data: '0x' + bin.toString(), arguments: contractParams}).encodeABI(); const nonce = await web3.eth.getTransactionCount(transactionParams.from); const rawTransactionObject = { gasLimit : transactionParams.gasLimit, gasPrice : transactionParams.gasPrice, data : deploy, nonce : nonce }; const rawTransaction = new tx(rawTransactionObject); rawTransaction.sign(transactionParams.mainOperatorPrivateKey); const serializedTx = rawTransaction.serialize(); const minedTxObject = await web3.eth.sendSignedTransaction('0x' + serializedTx.toString('hex')); resolve(minedTxObject); }) .catch((error) => { reject(error); });
- 10. Challenges
- 11. 1. Hard to find Blockchain Developer 2. Security Vulnerability in Smart Contracts ( 95% has Vulnerability ) 3. Problems in Ethereum Mainnet - Low TPS & High Transaction Fee Challenges
- 12. Lack of Blockchain Developers The top 10 fastest-growing skills, Q3 2017: 1. Robotics 2. Blockchain 3. Bitcoin 4. Penetration testing 5. React.js development 6. Amazon Web Services Lambda 7. Augmented reality 8. Deep learning 9. Instagram marketing 10. Final Cut Pro X https://hackernoon.com/blockchain-jobs-and-salaries-2018-report-45d3e7741c19
- 13. 1. Hard to find Blockchain Developer 2. Security Vulnerability in Smart Contracts ( 95% has Vulnerability ) 3. Problems in Ethereum Mainnet - Low TPS & High Transaction Fee Challenges
- 14. ▪ DAO Fund Hacking • Reentry attack • Ethereum Hard Fork ▪ SmartMesh ERC20 Hacking • Overflow Vulnerability • SmartMesh trade suspended ▪ Parity Multi-Sig Wallet Freeze • 500K Ether is freezed Unsecure Smart Contracts
- 15. 1. Hard to find Blockchain Developers 2. Security Vulnerability in Smart Contracts ( 95% has Vulnerability ) 3. Problems in Ethereum Mainnet - Low TPS & High Transaction Fee Challenges
- 16. Gas Used Gas Price (GWei) Ether Transaction Fee (in KRW) Ether Transfer 21,000 20 200,000 84 Contract Execution 150000 20 200,000 600
- 19. ▪ Lack of Smart Contract Developer → Token Launching Service ▪ Security Vulnerability in Smart Contracts → Token Launching Service ▪ High Transaction Fee ▪ Low TPS ▪ DApp Development ▪ Operation and Management of Blockchain Evolution
- 20. ▪ Deploy token smart contracts using pre-audited codes ▪ total supply, reserve and etc ▪ Deploy pre-audited Crowd Sale contract ▪ Setup steps by UI: private, pre-sale, public ▪ Deploy Crowd Sale Page Token Launching Services
- 21. ▪ Lack of Smart Contract Developer → Token Launching Service ▪ High Transaction Fee → Private Blockchain ▪ Low TPS ▪ DApp Development ▪ Operation and Management of Blockchain Evolution
- 22. ▪ Private Blockchain Network Service ▪ Amazon Blockchain Template ▪ Microsoft Azure Blockchain Workbench ▪ IBM Blockchain Platform ▪ Kaleido ▪ Provide only blockchain network Private Blockchain
- 23. ▪ Lack of Smart Contract Developer → Token Launching Service ▪ High Transaction Fee → Private Blockchain ▪ Low TPS → Sidechain ▪ DApp Development ▪ Operation and Management of Blockchain Evolution
- 24. ▪ Construct Private Blockchain ▪ DApp only uses Sidechain ▪ Transfer values between MainNet via Bridge DApp ▪ Deposit tokens ( Mainnet → Sidechain ) ▪ Withdraw tokens ( Sidechain → Mainnet ) ▪ Anchoring : Periodically write block hashes to mainnet Sidechain
- 25. ▪ Lack of Smart Contract Developer → Token Launching Service ▪ High Transaction Fee → Private Blockchain ▪ Low TPS → Private Blockchain & Sidechain ▪ DApp Development ▪ Operation/Management Problems of Blockchain Platform Evolution
- 27. Apply Decentralized Token Economy on your App in 30 minutes Luniverse
- 28. Steps for Applying Token Economy Contract Development ● Develop Token Contract ● Develop Crowd Sale Contract ● ... Private Blockchain Construction ● Construct Private Blockchain Network ● Deploy Private Blockchain Network Application Development ● Write and Test DApp ● Deploy DApp ● Write Business Logic in Smart Contract ● Solidity ● Truffle ● Web3.js ● Blockchain ● Cloud Platform ( AWS, Azure, …) ● Infrastructure Management ● Solidity ● Web3.js ● Truffle ● Metamask Deployment & Operation ● Manage Private Blockchain Network ● Deploy / Monitor / Shutdown / Recover ● Manage Private Keys ● Cloud Platform (AWS, Azure, …) ● Kubernetes, Ansible ● Truffle
- 29. ▪ Smart Wizard - Simple UI to create chains and tokens ▪ Open APIs - Easy integration with DApps ▪ Multi-sig bridge protocol - Secure token transfer among chains ▪ Reliable service and supports with HA Luniverse
- 30. Luniverse REST Server Token Economy on Application REST API REST Server Database REST API REST Server Database web3.js SmartContract Luniverse REST API
- 31. Create Main Token ▪ Main Token is on the Lunivere Main Chain ▪ Supported Tokens • Non Mintable Token • Mintable Token Luniverse Network Main Token Main Bridge Contract
- 32. Create Product Chain Node 1 Node 2 Node 3 Node 4 Node 5Node 6 Product Chain
- 37. Main Token → Product Token
- 38. Create Transactions ▪ Define Transactions on Product Token ▪ Transaction Types • Simple Transfer • Stake • Unstake • Vesting • Redeem
- 39. Transaction List
- 40. Check API Call
- 41. $.ajax({ url: 'https://xxx.xxx.xxxx/tx-api/api/v1.0/wallet/users/0xaedbb0bae7402841ed631267b989664eec635ea7/balances/token/DEMO/SPT', / type: 'get', crossDomain: true, dataType: 'json', success: function (data) { let sptBalance = data.data.balance || ''; $('#spt').text(sptBalance) }, error: function (data) { } }); $.ajax({ url: 'https://xxx.xxx.xxxx/tx-api/api/v1.0/wallet/users/0xaedbb0bae7402841ed631267b989664eec635ea7/balances/token/DEMO/ADT', type: 'get', crossDomain: true, dataType: 'json', success: function (data) { let adtBalance = data.data.balance || ''; $('#adt').text(adtBalance) }, error: function (data) { } }); API Call in your App
- 42. ▪ Provide Various Tokens : ERC223, ERC721 etc ▪ Provide Custom Smart Contract Transactions Future Works
- 43. Thank you
- 44. Sep, 2018 Token Platform based on Sidechain