スマートコントラクトプログラミング (3) イーサリアム実習 I / Ethereum Practice I

ブロックチェーンハブ主催で開催している (第2期) スマートコントラクトプログラミング講義 (3) 「イーサリアム実習 I」のスライドです。2017年5月24日(水) に使用しました。

Transcript

1. I (3) CSO / SFC ks91@sfc.wide.ad.jp I – (3) – 2017-05-24 – p.1/37
2. 1. 2. 3. 4. 5. I – (3) – 2017-05-24 – p.2/37
3. 1. : 2. ∼ ∼ I – (3) – 2017-05-24 – p.3/37
4. 1. : I – (3) – 2017-05-24 – p.4/37
5. BcH-smart-contract-programming.zip contracts tests I – (3) – 2017-05-24 – p.5/37
6. Solidity JavaScript ( , ) (constructor) ( ) ( ) Ether I – (3) – 2017-05-24 – p.6/37
7. pragma solidity ˆ0.4.8; contract MyToken { ( ) : (EVM ) : function MyToken(...) { /* */ : } : } function C (/* */ // ) I – (3) – 2017-05-24 – p.7/37
8. MyToken string public name; string public symbol; uint8 public decimals; mapping (address => uint256) public balanceOf; name, symbol decimals : 2 100 1.00 mapping balanceOf I – (3) – 2017-05-24 – p.8/37
9. MyToken event Transfer(address indexed from, address indexed to, uint256 value); indexed (3 ) MyToken function Transfer() Ethereum-Wallet I – (3) – 2017-05-24 – p.9/37
10. MyToken function MyToken(uint256 _supply, string _name, string _symbol, uint8 _decimals) { if (_supply == 0) { _supply = 1000000; /* _supply 1,000,000 */ } balanceOf[msg.sender] = _supply; name = _name; symbol = _symbol; decimals = _decimals; } msg.sender _supply C++ _ I – (3) – 2017-05-24 – p.10/37
11. MyToken getBalanceOf() function getBalanceOf(address _addr) returns (uint256 balance) { return (balanceOf[_addr]); } I – (3) – 2017-05-24 – p.11/37
12. MyToken transfer() function transfer(address _to, uint256 _value) { if (balanceOf[msg.sender] < _value) { /* */ throw; } if (balanceOf[_to] + _value < balanceOf[_to]) { /* */ throw; } balanceOf[msg.sender] -= _value; balanceOf[_to] += _value; Transfer(msg.sender, _to, _value); } throw (function ) catch I – (3) – 2017-05-24 – p.12/37
13. (1) import pytest @pytest.fixture() def token_contract(chain): TokenFactory = chain.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 – (3) – 2017-05-24 – p.13/37
14. (2) def test_my_token(token_contract, chain): account0 = chain.web3.eth.accounts[0] account1 = chain.web3.eth.accounts[1] assert token_contract.call().getBalanceOf(account0) == 1000000 assert token_contract.call().getBalanceOf(account1) == 0 txid = token_contract.transact().transfer(account1, 10) chain.wait.for_receipt(txid) assert token_contract.call().getBalanceOf(account0) == 999990 assert token_contract.call().getBalanceOf(account1) == 10 account0 coinbase account1 account0 account1 10BcH I – (3) – 2017-05-24 – p.14/37
15. $ py.test tests/test_my_token.py I – (3) – 2017-05-24 – p.15/37
16. 2. ∼ ∼ I – (3) – 2017-05-24 – p.16/37
17. A, B A-B m A B A B A B . . . I – (3) – 2017-05-24 – p.17/37
18. 1. X 2. X C 3. C 1. 2. 3. reliable multicast I – (3) – 2017-05-24 – p.18/37
19. : I – (3) – 2017-05-24 – p.19/37
20. (safety) (liveness) ( ) ( = ) I – (3) – 2017-05-24 – p.20/37
21. → / (benign) → (Byzantine) (malicious) I – (3) – 2017-05-24 – p.21/37
22. FLP Fischer, Lynch, Paterson I – (3) – 2017-05-24 – p.22/37
23. CAP Consistency ( ) Availability ( ) Partition tolerance ( ) ⇒ 3 C Eventual consistency ( ) . . . I – (3) – 2017-05-24 – p.23/37
24. Consistency ( ) Strong consistency ( ) (safety) Eventual consistency ( ) (liveness) ↑ Weak consistency ( ) ↑ ( ) I – (3) – 2017-05-24 – p.24/37
25. n = f ( ) ⇒ I – (3) – 2017-05-24 – p.25/37
26. (1) 1 1, 2 n ≤ 3f I – (3) – 2017-05-24 – p.26/37
27. (2) I – (3) – 2017-05-24 – p.27/37
28. CS1 : CS2 : CS3 : CL1 : CL2 : : : (e.g. ) I – (3) – 2017-05-24 – p.28/37
29. (B)FT-CUP (Consensus with Unknown Participants) ( / ) : FT (Fault-Tolerant) : BFT (Byzantine Fault-Tolerant) P2P n FT/BFT I – (3) – 2017-05-24 – p.29/37
30. State Machine Replication ( ) (by ) (since 1984) ( ) ( ) . . . ( ) I – (3) – 2017-05-24 – p.30/37
31. ( ) ( ) ( ) ( ) (by ) ⇒ ( ) I – (3) – 2017-05-24 – p.31/37
32. P2P : P2P 3 3 ( ) strategyproof group strategyproof I – (3) – 2017-05-24 – p.32/37
33. (Sybil) 16 I – (3) – 2017-05-24 – p.33/37
34. again n > 3f R F R > 2F ⇒ I – (3) – 2017-05-24 – p.34/37
35. ( ) f = 1 ⇒ R I – (3) – 2017-05-24 – p.35/37
36. (centralized) (decentralized) (distributed) Paul Baran, “On Distributed Communications Networks”, 1964 (C) (A) I – (3) – 2017-05-24 – p.36/37
37. II Hyperledger I – (3) – 2017-05-24 – p.37/37