イーサリアム実習 I / Ethereum Practice 1

2018年7月18日(水)、ブロックチェーンハブ主催で開催されたブロックチェーンアカデミー「イーサリアム実習 I」(【ハンズオン】スマートコントラクトプログラミング (2)) にて使用したスライドです。

Transcript

1. I (2) CSO / SFC ( https://speakerdeck.com/ks91 ) ks91@blockchainhub.co.jp I — (2) — 2018-07-18 – p.1/38
2. 1. 2. 3. 4. 5. I — (2) — 2018-07-18 – p.2/38
3. 1. : ERC20 2. ∼ ∼ I — (2) — 2018-07-18 – p.3/38
4. 1. : ERC20 ERC20 I — (2) — 2018-07-18 – p.4/38
5. (2018 7 18 ) BcH-smart-contract-programming.zip Solidity py.test solidity 0.4.22 + populus ongoing solidity 0.4.21 contracts tests I — (2) — 2018-07-18 – p.5/38
6. Solidity JavaScript ( , ) (constructor) ( ) ( ) Ether I — (2) — 2018-07-18 – p.6/38
7. pragma solidity ˆ0.4.24; contract MyToken { ( ) : (EVM ) : constructor (...) public { /* */ : } function MyToken(...) { /* ( ) */ : } : } constructor C (/* */ // ) I — (2) — 2018-07-18 – p.7/38
8. ERC20 ERC (Ethereum Request for Comment) 20 https://github.com/ethereum/EIPs/blob/master/EIPS/eip-20.md contract ERC20 { function totalSupply() constant returns (uint totalSupply); function balanceOf(address _owner) constant returns (uint balance); function transfer(address _to, uint _value) returns (bool success); function transferFrom(address _from, address _to, uint _value) returns (bool success); function approve(address _spender, uint _value) returns (bool success); function allowance(address _owner, address _spender) constant returns (uint remaining); event Transfer(address indexed _from, address indexed _to, uint _value); event Approval(address indexed _owner, address indexed _spender, uint _value); } name/ , symbol/ , decimals/ approve allowance ERC223 ( ), ERC721 (Non-Fungible) I — (2) — 2018-07-18 – p.8/38
9. MyToken string public _name; string public _symbol; uint8 public _decimals; mapping (address => uint256) public _balanceOf; uint256 _totalSupply; _name, _symbol _decimals : 2 100 1.00 mapping _balanceOf I — (2) — 2018-07-18 – p.9/38
10. MyToken event Transfer(address indexed from, address indexed to, uint256 value); indexed (3 ) MyToken function Transfer() I — (2) — 2018-07-18 – p.10/38
11. MyToken constructor (uint256 supply, string name, string symbol, uint8 decimals) public { if (supply == 0) { supply = 1000000; /* supply 1,000,000 */ } _totalSupply = supply; _balanceOf[msg.sender] = supply; _name = name; _symbol = symbol; _decimals = decimals; } msg.sender supply I — (2) — 2018-07-18 – p.11/38
12. MyToken balanceOf() function balanceOf(address tokenOwner) external view returns (uint256) { return _balanceOf[tokenOwner]; } I — (2) — 2018-07-18 – p.12/38
13. MyToken transfer() function transfer(address to, uint256 value) external returns (bool) { require(value <= _balanceOf[msg.sender]); /* */ require(_balanceOf[to] + value >= _balanceOf[to]); /* */ _balanceOf[msg.sender] -= value; _balanceOf[to] += value; Transfer(msg.sender, to, value); return true; } require (function ) OpenZeppelin https://openzeppelin.org I — (2) — 2018-07-18 – p.13/38
14. (1) import pytest @pytest.fixture() def token_contract(chain): TokenFactory = chain.provider.get_contract_factory(’MyToken’) deploy_txid = TokenFactory.deploy(args=[ 0, "BcH Coin", "BcH", 0, ]) contract_address = chain.wait.for_contract_address(deploy_txid) return TokenFactory(address=contract_address) populus I — (2) — 2018-07-18 – p.14/38
15. (2) def test_my_token(token_contract, chain): account0 = chain.web3.eth.accounts[0] account1 = chain.web3.eth.accounts[1] assert token_contract.call().balanceOf(account0) == 1000000 assert token_contract.call().balanceOf(account1) == 0 txid = token_contract.transact().transfer(account1, 10) chain.wait.for_receipt(txid) assert token_contract.call().balanceOf(account0) == 999990 assert token_contract.call().balanceOf(account1) == 10 account0 coinbase account1 account0 account1 10BcH I — (2) — 2018-07-18 – p.15/38
16. $ py.test -k test_my_token.py I — (2) — 2018-07-18 – p.16/38
17. 2. ∼ ∼ I — (2) — 2018-07-18 – p.17/38
18. A, B A-B m A B A B A B . . . I — (2) — 2018-07-18 – p.18/38
19. 1. X 2. X C 3. C 1. 2. 3. reliable multicast I — (2) — 2018-07-18 – p.19/38
20. : I — (2) — 2018-07-18 – p.20/38
21. (safety) (liveness) ( ) ( = ) I — (2) — 2018-07-18 – p.21/38
22. → / (benign) → (Byzantine) (malicious) I — (2) — 2018-07-18 – p.22/38
23. FLP Fischer, Lynch, Paterson I — (2) — 2018-07-18 – p.23/38
24. CAP Consistency ( ) Availability ( ) Partition tolerance ( ) ⇒ 3 C Eventual consistency ( ) . . . I — (2) — 2018-07-18 – p.24/38
25. Consistency ( ) Strong consistency ( ) (safety) Eventual consistency ( ) (liveness) ↑ Weak consistency ( ) ↑ ( ) I — (2) — 2018-07-18 – p.25/38
26. n = f ( ) ⇒ I — (2) — 2018-07-18 – p.26/38
27. (1) 1 1, 2 n ≤ 3f I — (2) — 2018-07-18 – p.27/38
28. (2) I — (2) — 2018-07-18 – p.28/38
29. CS1 : CS2 : CS3 : CL1 : CL2 : : : (e.g. ) I — (2) — 2018-07-18 – p.29/38
30. (B)FT-CUP (Consensus with Unknown Participants) ( / ) : FT (Fault-Tolerant) : BFT (Byzantine Fault-Tolerant) P2P n FT/BFT I — (2) — 2018-07-18 – p.30/38
31. State Machine Replication ( ) (by ) (since 1984) ( ) ( ) . . . ( ) I — (2) — 2018-07-18 – p.31/38
32. ( ) ( ) ( ) ( ) (by ) ⇒ ( ) I — (2) — 2018-07-18 – p.32/38
33. P2P : P2P 3 3 ( ) strategyproof group strategyproof I — (2) — 2018-07-18 – p.33/38
34. (Sybil) 16 I — (2) — 2018-07-18 – p.34/38
35. again n > 3f R F R > 2F ⇒ I — (2) — 2018-07-18 – p.35/38
36. ( ) f = 1 ⇒ R I — (2) — 2018-07-18 – p.36/38
37. (centralized) (decentralized) (distributed) Paul Baran, “On Distributed Communications Networks”, 1964 (C) (A) I — (2) — 2018-07-18 – p.37/38
38. II : : / I — (2) — 2018-07-18 – p.38/38