標籤彙整: 以太幣

虛擬貓咪原始碼&智慧合約入門筆記

最近想多了解智慧合約的實際應用狀況,希望能跟區塊鏈上的智慧合約做簡單互動。

於是找了目前最成功的應用之一「虛擬貓咪」來研究。

分享一下目前的研究心得。

在開始之前,可以先閱讀以下兩個連結,對於閱讀本文會非常有幫助:

https://medium.com/loom-network/how-to-code-your-own-cryptokitties-style-game-on-ethereum-7c8ac86a4eb3

https://medium.com/loom-network/your-crypto-kitty-isnt-forever-why-dapps-aren-t-as-decentralized-as-you-think-871d6acfea

智慧合約不是完全公開透明的

以虛擬貓咪為例,智慧合約本身看似可以在此取得:

https://etherscan.io/address/0x06012c8cf97bead5deae237070f9587f8e7a266d#code

但貓咪基因科學的合約是額外佈署的,不但可以由作者動態修改,而且還只有 opcode 可讀。

同樣的道理,您也可以利用這種「設定外部合約」並且不公佈那份外部合約的 Solidity 原始碼,來達成這種保密效果,還讓合約保持可以更新、升級的空間。

智慧合約不是完全去中心化的

除此之外,虛擬貓咪智慧合約定義了 CEO、CFO、COO 三個管理員角色。這三個角色各自有額外權力,甚至可以凍結整個合約的運行。

不僅如此,區塊鏈上的資料看似永恆,但其實除了原始團隊,沒人可以解讀基因編碼。因此一大部份 value 還是來自傳統 web server。所以虛擬貓咪根本沒辦法脫離作者團隊獨立存活。

如何用 web3.js 讀取 address balance?以我與虛擬貓咪為例

要讀取每個地址的以太幣餘額,最簡單的方式就是直接透過 etherscan.io

比如說,我的個人餘額可以在此查看:https://etherscan.io/address/0xcb0418eae76e14c214d79b8305ca34669075cba6

而虛擬貓咪這份合約地址的餘額,可以在此查看:https://etherscan.io/address/0x06012c8cf97bead5deae237070f9587f8e7a266d

以工程師的立場,會希望用程式去跟區塊鏈互動。以在網頁內使用 web3.js 為例,安裝了 MetaMask 來連線到區塊鏈之後,可以用以下程式碼讀取地址餘額:

  var web3Provider = web3.currentProvider;

  var web3 = new Web3(web3Provider);

  var tonyAddress = '0xcb0418eae76e14c214d79b8305ca34669075cba6';

  var cryptoKittiesContractAddress = '0x06012c8cf97bead5deae237070f9587f8e7a266d';

  web3.eth.getBalance(tonyAddress, function(error, result){
    console.log('tony balance: ' + result);
  });

  web3.eth.getBalance(cryptoKittiesContractAddress, function(error, result){
    console.log('crypto kitties balance: ' + result);
  });

如何用 web3.js 讀取智慧合約的 public variable?以虛擬貓咪為例

試著讀取智慧合約中三個公開變數的值。最簡單的方式一樣是透過 etherscan.io

可以在這裡看到三個管理員(CEO、COO、CFO)的地址: https://etherscan.io/address/0x06012c8cf97bead5deae237070f9587f8e7a266d#readContract

用 web3.js 來讀取的話,可以先去 etherscan.io 取得合約的 ABI:

https://etherscan.io/address/0x06012c8cf97bead5deae237070f9587f8e7a266d#code

接著像這樣從區塊鏈上讀出值:

  var web3Provider = web3.currentProvider;

  var web3 = new Web3(web3Provider);

  var cryptoKittiesContractAddress = '0x06012c8cf97bead5deae237070f9587f8e7a266d';

  var AbiOfContract = [{"constant":true,"inputs":[{"name":"_interfaceID","type":"bytes4"}],"name":"supportsInterface","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"cfoAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_tokenId","type":"uint256"},{"name":"_preferredTransport","type":"string"}],"name":"tokenMetadata","outputs":[{"name":"infoUrl","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"promoCreatedCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_tokenId","type":"uint256"}],"name":"approve","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"ceoAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"GEN0_STARTING_PRICE","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_address","type":"address"}],"name":"setSiringAuctionAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"pregnantKitties","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_kittyId","type":"uint256"}],"name":"isPregnant","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"GEN0_AUCTION_DURATION","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"siringAuction","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_tokenId","type":"uint256"}],"name":"transferFrom","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_address","type":"address"}],"name":"setGeneScienceAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_newCEO","type":"address"}],"name":"setCEO","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_newCOO","type":"address"}],"name":"setCOO","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_kittyId","type":"uint256"},{"name":"_startingPrice","type":"uint256"},{"name":"_endingPrice","type":"uint256"},{"name":"_duration","type":"uint256"}],"name":"createSaleAuction","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"unpause","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"sireAllowedToAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_matronId","type":"uint256"},{"name":"_sireId","type":"uint256"}],"name":"canBreedWith","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"kittyIndexToApproved","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_kittyId","type":"uint256"},{"name":"_startingPrice","type":"uint256"},{"name":"_endingPrice","type":"uint256"},{"name":"_duration","type":"uint256"}],"name":"createSiringAuction","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"val","type":"uint256"}],"name":"setAutoBirthFee","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_addr","type":"address"},{"name":"_sireId","type":"uint256"}],"name":"approveSiring","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_newCFO","type":"address"}],"name":"setCFO","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_genes","type":"uint256"},{"name":"_owner","type":"address"}],"name":"createPromoKitty","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"secs","type":"uint256"}],"name":"setSecondsPerBlock","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"paused","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"withdrawBalance","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_tokenId","type":"uint256"}],"name":"ownerOf","outputs":[{"name":"owner","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"GEN0_CREATION_LIMIT","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"newContractAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_address","type":"address"}],"name":"setSaleAuctionAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"count","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_v2Address","type":"address"}],"name":"setNewAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"secondsPerBlock","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"pause","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"tokensOfOwner","outputs":[{"name":"ownerTokens","type":"uint256[]"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_matronId","type":"uint256"}],"name":"giveBirth","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"withdrawAuctionBalances","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"cooldowns","outputs":[{"name":"","type":"uint32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"kittyIndexToOwner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_tokenId","type":"uint256"}],"name":"transfer","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"cooAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"autoBirthFee","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"erc721Metadata","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_genes","type":"uint256"}],"name":"createGen0Auction","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_kittyId","type":"uint256"}],"name":"isReadyToBreed","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"PROMO_CREATION_LIMIT","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_contractAddress","type":"address"}],"name":"setMetadataAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"saleAuction","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_id","type":"uint256"}],"name":"getKitty","outputs":[{"name":"isGestating","type":"bool"},{"name":"isReady","type":"bool"},{"name":"cooldownIndex","type":"uint256"},{"name":"nextActionAt","type":"uint256"},{"name":"siringWithId","type":"uint256"},{"name":"birthTime","type":"uint256"},{"name":"matronId","type":"uint256"},{"name":"sireId","type":"uint256"},{"name":"generation","type":"uint256"},{"name":"genes","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_sireId","type":"uint256"},{"name":"_matronId","type":"uint256"}],"name":"bidOnSiringAuction","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"constant":true,"inputs":[],"name":"gen0CreatedCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"geneScience","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_matronId","type":"uint256"},{"name":"_sireId","type":"uint256"}],"name":"breedWithAuto","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":false,"name":"owner","type":"address"},{"indexed":false,"name":"matronId","type":"uint256"},{"indexed":false,"name":"sireId","type":"uint256"},{"indexed":false,"name":"cooldownEndBlock","type":"uint256"}],"name":"Pregnant","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"from","type":"address"},{"indexed":false,"name":"to","type":"address"},{"indexed":false,"name":"tokenId","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"owner","type":"address"},{"indexed":false,"name":"approved","type":"address"},{"indexed":false,"name":"tokenId","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"owner","type":"address"},{"indexed":false,"name":"kittyId","type":"uint256"},{"indexed":false,"name":"matronId","type":"uint256"},{"indexed":false,"name":"sireId","type":"uint256"},{"indexed":false,"name":"genes","type":"uint256"}],"name":"Birth","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"newContract","type":"address"}],"name":"ContractUpgrade","type":"event"}];

  var contractAbi = web3.eth.contract(AbiOfContract);

  var myContract = contractAbi.at(cryptoKittiesContractAddress);

  myContract.ceoAddress(function(error, result){
    console.log('ceo address: ' + result);
  });

  myContract.cooAddress(function(error, result){
    console.log('coo address: ' + result);
  });

  myContract.cfoAddress(function(error, result){
    console.log('cfo address: ' + result);
  });

如何用 web3.js 呼叫智慧合約的 public function?以虛擬貓咪為例

呼叫公開函式的話,最簡單的方法是透過 etherscan.io。

以虛擬貓咪的 getKitty 函式為例,如果要找出 ID 為 1 的那隻創世貓咪的資料,只要在欄位內輸入送出即可:

https://etherscan.io/address/0x06012c8cf97bead5deae237070f9587f8e7a266d#readContract

用 web3.js 來讀取的話,則可以像這樣來呼叫函式(以分別抓出1、2、3 三隻貓咪為例):

  var web3Provider = web3.currentProvider;

  var web3 = new Web3(web3Provider);

  var cryptoKittiesContractAddress = '0x06012c8cf97bead5deae237070f9587f8e7a266d';

  var AbiOfContract = [{"constant":true,"inputs":[{"name":"_interfaceID","type":"bytes4"}],"name":"supportsInterface","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"cfoAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_tokenId","type":"uint256"},{"name":"_preferredTransport","type":"string"}],"name":"tokenMetadata","outputs":[{"name":"infoUrl","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"promoCreatedCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_tokenId","type":"uint256"}],"name":"approve","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"ceoAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"GEN0_STARTING_PRICE","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_address","type":"address"}],"name":"setSiringAuctionAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"pregnantKitties","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_kittyId","type":"uint256"}],"name":"isPregnant","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"GEN0_AUCTION_DURATION","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"siringAuction","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_tokenId","type":"uint256"}],"name":"transferFrom","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_address","type":"address"}],"name":"setGeneScienceAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_newCEO","type":"address"}],"name":"setCEO","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_newCOO","type":"address"}],"name":"setCOO","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_kittyId","type":"uint256"},{"name":"_startingPrice","type":"uint256"},{"name":"_endingPrice","type":"uint256"},{"name":"_duration","type":"uint256"}],"name":"createSaleAuction","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"unpause","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"sireAllowedToAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_matronId","type":"uint256"},{"name":"_sireId","type":"uint256"}],"name":"canBreedWith","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"kittyIndexToApproved","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_kittyId","type":"uint256"},{"name":"_startingPrice","type":"uint256"},{"name":"_endingPrice","type":"uint256"},{"name":"_duration","type":"uint256"}],"name":"createSiringAuction","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"val","type":"uint256"}],"name":"setAutoBirthFee","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_addr","type":"address"},{"name":"_sireId","type":"uint256"}],"name":"approveSiring","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_newCFO","type":"address"}],"name":"setCFO","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_genes","type":"uint256"},{"name":"_owner","type":"address"}],"name":"createPromoKitty","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"secs","type":"uint256"}],"name":"setSecondsPerBlock","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"paused","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"withdrawBalance","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_tokenId","type":"uint256"}],"name":"ownerOf","outputs":[{"name":"owner","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"GEN0_CREATION_LIMIT","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"newContractAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_address","type":"address"}],"name":"setSaleAuctionAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"count","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_v2Address","type":"address"}],"name":"setNewAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"secondsPerBlock","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[],"name":"pause","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"tokensOfOwner","outputs":[{"name":"ownerTokens","type":"uint256[]"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_matronId","type":"uint256"}],"name":"giveBirth","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[],"name":"withdrawAuctionBalances","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"cooldowns","outputs":[{"name":"","type":"uint32"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"kittyIndexToOwner","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_tokenId","type":"uint256"}],"name":"transfer","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"cooAddress","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"autoBirthFee","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"erc721Metadata","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_genes","type":"uint256"}],"name":"createGen0Auction","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"_kittyId","type":"uint256"}],"name":"isReadyToBreed","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"PROMO_CREATION_LIMIT","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_contractAddress","type":"address"}],"name":"setMetadataAddress","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"saleAuction","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_id","type":"uint256"}],"name":"getKitty","outputs":[{"name":"isGestating","type":"bool"},{"name":"isReady","type":"bool"},{"name":"cooldownIndex","type":"uint256"},{"name":"nextActionAt","type":"uint256"},{"name":"siringWithId","type":"uint256"},{"name":"birthTime","type":"uint256"},{"name":"matronId","type":"uint256"},{"name":"sireId","type":"uint256"},{"name":"generation","type":"uint256"},{"name":"genes","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_sireId","type":"uint256"},{"name":"_matronId","type":"uint256"}],"name":"bidOnSiringAuction","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"constant":true,"inputs":[],"name":"gen0CreatedCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"geneScience","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_matronId","type":"uint256"},{"name":"_sireId","type":"uint256"}],"name":"breedWithAuto","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"payable":true,"stateMutability":"payable","type":"fallback"},{"anonymous":false,"inputs":[{"indexed":false,"name":"owner","type":"address"},{"indexed":false,"name":"matronId","type":"uint256"},{"indexed":false,"name":"sireId","type":"uint256"},{"indexed":false,"name":"cooldownEndBlock","type":"uint256"}],"name":"Pregnant","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"from","type":"address"},{"indexed":false,"name":"to","type":"address"},{"indexed":false,"name":"tokenId","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"owner","type":"address"},{"indexed":false,"name":"approved","type":"address"},{"indexed":false,"name":"tokenId","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"owner","type":"address"},{"indexed":false,"name":"kittyId","type":"uint256"},{"indexed":false,"name":"matronId","type":"uint256"},{"indexed":false,"name":"sireId","type":"uint256"},{"indexed":false,"name":"genes","type":"uint256"}],"name":"Birth","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"newContract","type":"address"}],"name":"ContractUpgrade","type":"event"}];

  var contractAbi = web3.eth.contract(AbiOfContract);
  var myContract = contractAbi.at(cryptoKittiesContractAddress);

  myContract.getKitty(1, function(error, result){
    console.log('kitty info: ' + result);
  });

  myContract.getKitty(2, function(error, result){
    console.log('kitty info: ' + result);
  });

  myContract.getKitty(3, function(error, result){
    console.log('kitty info: ' + result);
  });

心得感想

像這樣的智慧合約,究竟有多少應用場景?

一個 dapp 該去中心化到什麼程度?智慧合約的未來到底有多少潛力?實在沒人有把握。

還是老話一句,建議有心參與的朋友,保持懷疑精神,花時間了解更多,建立自己的觀點跟看法,不要輕信任何人的說法。

(完)

Ethereum 智慧合約佈署初體驗:數據與成本分享

正式佈署一份智慧合約是什麼感覺?

它的佈署速度、佈署成本又是多少呢?

我親自跑了一次流程。分享一下實際的數據與心得。

發行個人專屬加密貨幣:阿川幣

我直接拿官網的範例程式碼來修改參數,發行阿川幣:

https://ethereum.org/token

官網提供兩份範本,一份只有基本功能,一份具備進階功能。

以太錢包預估了基本合約的佈署成本是 0.000715604 ether(約合新台幣 22 元):

erc20

而進階合約的佈署成本是 0.001010363 ether(約合新台幣 31 元):

advanced

我選擇佈署基本合約就好。輸入參數之後,會發現成本微幅提昇到 0.000777146 ether(約合新台幣 24 元):

with-parameters

按下 DEPLOY 按鈕,會確認密碼,並顯示預估成本 0.000777146 ether 是因為預估耗用 777,146 gas,並且多準備 0.0001 ether 作為緩衝:

gas-usage

送出後,以太錢包會顯示 etherscan.io 網站上的交易連結:

https://etherscan.io/tx/0xcedd9b10deb6ca64b44a547244045383d4563f916849c005308453d939f69c51

大約 6 分鐘後,網頁上的交易狀態顯示為 success:

6-min-success

不過以太錢包內還沒有同步顯示完成。再過 4 分鐘,也就是大約 10 分鐘後,以太錢包上才顯示 created:

10-min-success

進入帳號底下查看,會看到 2,100 萬枚阿川幣正確顯示,代表合約佈署完成了。

我本來有 0.01 ether,現在剩 0.009222854 ether,所以的確是被扣款 0.000777146 ether,以太錢包的預估成本是準確的:

final-balance

並且可以查看合約的地址,合約的原始碼也在裡面:

https://etherscan.io/address/0x03f6a68baf85840a513a71f49f5f8fb1edcf27f6

心得感想

這次初體驗,以個人用戶來說,我認為佈署速度不算太慢(約 6 – 10 分鐘),手續費也還行(約合新台幣 24 元),都還 OK。

所以佈署這種範例程式碼等級的合約,不困難,也不昂貴。

可以以此為基礎,再進一步研發更複雜的智慧合約。

至於智慧合約的未來到底有多少潛力?其實沒人有把握。

還是建議有心參與的朋友,保持懷疑精神,建立自己的觀點跟看法,不要輕信任何人的說法。

(完)

以太幣購買與傳送初體驗:數據與心得分享

購買與轉帳加密貨幣,究竟是什麼感覺?

它的交易速度、交易成本又是多少呢?

我親自跑了一次流程。分享一下實際的數據與心得。

在 MaiCoin 註冊帳號

我選擇的加密貨幣是以太幣。

台灣能購買以太幣的管道不多,查詢之後決定使用 MaiCoin 的服務,因為可以在萊爾富繳費。

https://www.maicoin.com/

原本只想買個新台幣 300 元,但發現 MaiCoin 規定單次購買至少要滿 0.05 枚以太幣,當下約合新台幣 1,806 元。

所以我用這數字下單了,確認後取得了萊爾富的繳費代碼。

因為匯率波動太大,MaiCoin 提醒我要在 15 分鐘內繳費,否則可能以新匯率計價。

在萊爾富使用代碼繳費

我到萊爾富時已經超過 15 分鐘了,使用 Life-ET 代碼繳費,萊爾富收取手續費 20 元,總計支出 1,826 元,繳費完成。

在 MaiCoin 確認交易完成

回家打開 MaiCoin 網站,馬上確認了繳費完畢,並顯示我帳號擁有 0.04984127 枚以太幣。因為匯率變動,我受到了小小損失。

111

使用 Ethereum Wallet 建立帳號(address)

MaiCoin 上的以太幣是記在 MaiCoin 底下,為了建立一個正式的以太坊地址,我使用了官方的 Ethereum Wallet 建立帳號,並取得地址。

從 MaiCoin 傳送以太幣到我的 address

MaiCoin 規定傳送的以太幣數量至少為 0.01。

確認之後,明細會顯示處理中。

222

在 etherchain.org 確認交易內容

MaiCoin 約 11 分鐘後通知我,確認交易完成。

我電腦上的 Ethereum Wallet 需要下載完所有區塊鏈資料(目前約為 55.1 GB!),才能顯示我的帳戶餘額。

不想等這麼多資料下載完,所以我去 etherchain.org 上確認區塊鏈內容。

區塊編號  4992415 ,實際交易時間約為 9 分鐘。

https://www.etherchain.org/tx/0x37f3597ee17754494ba88e732f6ff32ed604b18fac9e786071089ea773d39501

交易內容 0.01 ETH ,約合美金 $12.31。

交易手續費 0.00084 ETH,約合美金 $1.03,這費用是由 MaiCoin 支付,沒有扣到我身上。

55 GB 資料下載完後,我也在錢包上看到了餘額 0.01 ETHER 沒有錯。

333

心得感想

這次初體驗,以個人用戶來說,我認為交易速度不算太慢,還 OK,手續費也還行。

但是作為投資則非常困難,除了手續費之外,在 MaiCoin 上的匯率跟國外交易所的匯率也有差別。

整體說起來,想到這段金融過程,幾乎沒有銀行或是政府機構介入,而是由全世界各地的電腦一起完成,確實感覺區塊鏈科技滿酷的。

但許多 ICO 相關詐騙、根本沒用的區塊鏈假應用、三不五時傳出的交易所危機等等,讓人不得不保持戒心。

建議有心參與的朋友,以學術精神,保持懷疑,勇於懷疑,建立自己的觀點跟看法,不要輕信任何人的說法。

(完)