EExcel 丞燕快速查詢2

EExcel 丞燕快速查詢2
EExcel 丞燕快速查詢2 https://sandk.ffbizs.com/

修行

你從那裡來? 妄想從那裡來?

心自體不可得,作用可得

開顯自己的真如本性
修行從裡面(內在)生起,這個心誰都不能破壞

印光大師說:全世界的人念佛都沒有感應,全世界的人念佛都沒求生淨土,我照樣念佛,我照樣求生淨土

跟外境沒有關係

不生滅心

https://youtu.be/iudlojChsKs?list=PLA16E144975D1AFCD&t=1963



修正自己的行為

[轉]解決replacement transaction underpriced以太坊交易異常

https://www.twblogs.net/a/5bb2596a2b71770e645ddc3c

replacement transaction underpriced異常

問題概述

以太坊系列(ETH&ETC)在發送交易有三個對應的RPC接口,分別是ethsendTransaction、ethsendRawTransaction和personal_sendTransaction。這三個接口發送(或構造發送內容時)都需要一個參數nonce。官方文檔對此參數的解釋是:整數類型,允許使用相同隨機數覆蓋自己發送的處於pending狀態的交易。

僅從官網的解釋,我們無法獲取到更多的有效的信息。但在真實生成中我們會發現如果傳錯nonce字段值,通過RPC接口調用發送的交易很大可能將不會被確認。如果通過console命令來操作一般不會出現此問題,因爲節點已經幫我們處理了。

如果繼續追蹤問題,會發現nonce傳遞錯誤的交易可以通過eth_getTransaction查詢得到相關信息,但是它的blocknumber始終未null,也就說這邊交易始終未被確認。如果是在dev模式下,應該是很快就會被確認的。更進一步,通過txpool.content命令,會發現那筆交易一直處於queued隊列中,而未被消費。

在使用同一個地址連續發送交易時,每筆交易往往不可能立即到賬, 當前交易還未到賬的情況下,下一筆交易無論是通過eth.getTransactionCount()獲取nonce值來設置,還是由節點自動從區塊中查詢,都會獲得和前一筆交易同樣的nonce值,這時節點就會報錯Error: replacement transaction underpriced

爲了防止交易重播,ETH(ETC)節點要求每筆交易必須有一個nonce數值。每一個賬戶從同一個節點發起交易時,這個nonce值從0開始計數,發送一筆nonce對應加1。當前面的nonce處理完成之後纔會處理後面的nonce。注意這裏的前提條件是相同的地址在相同的節點發送交易。 以下是nonce使用的幾條規則:

● 當nonce太小(小於之前已經有交易使用的nonce值),交易會被直接拒絕。

● 當nonce太大,交易會一直處於隊列之中,這也就是導致我們上面描述的問題的原因;

● 當發送一個比較大的nonce值,然後補齊開始nonce到那個值之間的nonce,那麼交易依舊可以被執行。

● 當交易處於queue中時停止geth客戶端,那麼交易queue中的交易會被清除掉。

如果系統中的熱點賬戶或普通賬戶發起交易時出現error: replacement transaction underpriced異常,那麼就需要考慮nonce使用是否正確。

引起此異常原因主要是當一個賬戶發起一筆交易,假設使用nonce爲1,交易已經發送至節點中,但由於手續費不高或網絡擁堵或nonce值過高,此交易處於queued中遲遲未被打包。

同時此地址再發起一筆交易,如果通過eth_getTransactionCount獲取的nonce值與上一個nonce值相同,用同樣的nonce值再發出交易時,如果手續費高於原來的交易,那麼第一筆交易將會被覆蓋,如果手續費低於原來的交易就會發生上面的異常。

通常發生此異常意味着:
- 你的Ethereum客戶端中已經有一筆處於pending狀態的交易。
- 新的一筆交易擁有pending狀態交易相同的nonce值。

- 新的交易的gas price太小,無法覆蓋pending狀態的交易。

通常情況下,覆蓋掉一筆處於pending狀態的交易gas price需要高於原交易的110%。

經過上面的解釋追蹤,我們已經瞭解到了nonce的基本使用規則。那麼,在實際應該用中我們如何保障nonce值的可靠性呢?這裏有兩個思路,

第一個思路就是由業務系統維護nonce值的遞增。如果交易發送就出現問題,那麼該地址下一筆交易繼續使用這個nonce進行發送交易。


第二個思路就是使用現有的api查詢當前地址已經發送交易的nonce值,然後對其加1,再發送交易。對應的API接口爲:eth_getTransactionCount,此方法由兩個參數,第一個參數爲需要查詢nonce的地址,第二個參數爲block的狀態:latest、earliest和pending。一般情況使用pending就可以查詢獲得最新已使用的nonce。其他狀態大家可以自行驗證。


第三個思路就
如果該熱點賬戶的私鑰信息等都存放在Ethereum客戶端中,那麼在發送交易的時候不傳遞nonce值,Ethereum客戶端會幫你處理好此nonce值的排序。


當然,此方案有兩個弊端。第一個是安全性無法保障(未進行冷熱賬戶分離),第二,在熱點賬戶下如果想覆蓋掉一筆交易,需要先查詢一下該交易的信息,從中獲取nonce值。

第一個思路

自行管理nonce適用於冷熱賬戶模式,也就是適用sendRawTransaction發送已經簽名好的交易時,此時nonce值已經存在於交易中,並且已經被簽名。

這種模式下,需要在業務系統中維護nonce的自增序列,使用一個nonce之後,在業務系統中對nonce進行加一處理。

此種方案也有限制條件。第一,由於nonce統一進行維護,那麼這個地址必須是內部地址,而且發起交易必須通過統一維護的nonce作爲出口,否則在其他地方發起交易,原有維護的nonce將會出現混亂。第二,一旦已經發出的交易發生異常,異常交易的nonce未被使用,那麼異常交易的nonce需要重新被使用之後它後面的nonce纔會生效。

在構建一筆新的交易時,在交易數據結構中會產生一個nonce值, nonce是當前區塊鏈下,發送者(from地址)發出的交易(成功記錄進區塊的)總數, 再加上1。例如新構建一筆從A發往B的交易,A地址之前的交易次數爲10,那麼這筆交易中的nonce則會設置成11, 節點驗證通過後則會放入交易池(txPool),並向其他節點廣播,該筆交易等待礦工將其打包進新的區塊。

第二個思路

那麼,如果在先構建併發送了一筆從地址A發出的,nonce爲11的交易,在該交易未打包進區塊之前, 再次構建一筆從A發出的交易,並將它發送到節點,不管是先通過web3的eth.getTransactionCount(A)獲取到的過往的交易數量,還是由節點自行填寫nonce, 後面的這筆交易的nonce同樣是11, 此時就出現了問題:

後面的這筆交易手續費給得更高, 那麼節點會前面的那筆交易從交易池中剔除,轉而放入後面構建的這筆交易
如果後面的這筆交易給得不夠高, 就會被廢棄掉, 如果通過web3這樣的sdk來向節點發送交易時,會收到錯誤信息

實際場景中

,會有批量從一個地址發送交易的需求,首先這些操作可能也應該是並行的,我們不會等待一筆交易成功寫入區塊後再發起第二筆交易,那麼此時有什麼好的解決辦法呢?先來看看geth節點中交易池對交易的處理流程

如之前所說,

第三個思路

構建一筆交易時如果不手動設置nonce值,geth節點會默認計算發起地址此前最大nonce數(寫入區塊的才算數),然後將其加上1, 然後將這筆交易放入節點交易池中的pending隊列,等到節點將其打包進區塊。

第一個思路

構建交易時,nonce值是可以手動設置的,如果當前的nonce本應該設置成11, 但是我手動設置成了13, 在節點收到這筆交易時, 發現pending隊列中並沒有改地址下nonce爲11及12的交易, 就會將這筆nonce爲13的交易放入交易池的queued隊列中。只有當前面的nonce補齊(nonce爲11及12的交易被發現並放入pending隊列)之後,纔會將它放入pending隊列中等待打包。

我們把pending隊列中的交易視爲可執行的,因爲它們可能被礦工打包進最新的區塊。 而queue隊列因爲前面的nonce存在缺失,暫時無法被礦工打包,稱爲不可執行交易。

那麼

實際開發中
,批量從一個地址發送交易時,應該怎麼辦呢?


方案一:

那麼在批量從一個地址發送交易時, 可以持久化一個本地的nonce,構建交易時用本地的nonce去累加,逐一填充到後面的交易。(要注意本地的nonce可能會出現偏差,可能需要定期從區塊中重新獲取nonce,更新至本地)。這個方法也有一定的侷限性,適合內部地址(即只有這個服務會使用該地址發送交易)。

說到

這裏還有個坑

,許多人認爲通過eth.getTransactionCount(address, "pending"),第二個參數爲pending, 就能獲得包含本地交易池pending隊列的nonce值,但是實際情況並不是這樣, 這裏的pending只包含待放入打包區塊的交易, 假設已寫入交易區塊的數量爲20, 又發送了nonce爲21,22,23的交易, 通過上面方法取得nonce可能是21(前面的21,22,23均未放入待打包區塊), 也可能是22(前面的21放入待打包區塊了,但是22,23還未放入)。

新版本的Geth好像解決了這個問題,在超大量測試transaction中,沒發現上述情況,如這問題還在應該會是大量錯誤一直產生才對!

超大量測試transaction

方案二:

是每次構建交易時,從geth節點的pending隊列取到最後一筆可執行交易的nonce, 在此基礎上加1,再發送給節點。可以通過txpool.content或txpool.inspect來獲得交易池列表,裏面可以看到pending及queue的交易列表。

其他方式:

啓動節點時,是可以設置交易池中的每個地址的pending隊列的容量上限,queue隊列的上容量上限, 以及整個交易池的pending隊列和queue隊列的容量上限。所以高併發的批量交易中,需要增加節點的交易池容量。

當然,除了擴大交易池,控制發送頻率,更要設置合理的交易手續費,eth上交易寫入區塊的速度取決於手續費及eth網絡的擁堵狀況,發送每筆交易時,設置合理的礦工費用,避免大量的交易積壓在交易池。

How to test your self ethereum geth private poa truffle

Important!! web3.eth.sendTransaction({ data: bytecode

"certjson.bytecode" or "certjson.bytecode.object"

MUST Have "0x" at line First Character


Use Truffle


1. run https://www.trufflesuite.com/docs/truffle/quickstart

1-1. run command


mkdir testtruffle
cd testtruffle
npm i web3

truffle unbox metacoin
truffle test ./test/TestMetaCoin.sol
truffle test ./test/metacoin.js
truffle compile

2. modify truffle-config.js
Here use your private poa chain networkinfo. from address must be can used. genesis file can put this address.


module.exports = {
  // Uncommenting the defaults below 
  // provides for an easier quick-start with Ganache.
  // You can also follow this format for other networks;
  // see 
  // for more details on how to specify configuration options!
  //
  networks: {
    development: {
      host: "192.168.99.100",
      port: 8545,
      network_id: "*",
      from: "0x5921a4c1b13afbd4b61d63e9c7bd47741c47b176"
    },
  //  test: {
  //    host: "127.0.0.1",
  //    port: 7545,
  //    network_id: "*"
  //  }
  }
  
};

3. modify migrations/1_initial_migration.js

If account have password, remark some line to put password. Here example no password.

Import: importRawKey maybe run one time, get error msg "Error: Returned error: account already exists" then remark.


Import: if unlock failed, may be is geth new version need to add --allow-insecure-unlock



const Web3 = require('web3');
const TruffleConfig = require('../truffle-config.js');

const Migrations = artifacts.require("Migrations");

module.exports = function(deployer) {
  const config = TruffleConfig.networks.development;

  //if (process.env.ACCOUNT_PASSWORD) {
    const web3 = new Web3(new Web3.providers.HttpProvider('http://' + config.host + ':' + config.port));

    // maybe only run one time for geth
    // web3.eth.personal.importRawKey('d05bd152f3d71ff5f91830f3ccc1090fb670c7026ebf8c2136d4e5090d59398d', '')
    // web3.eth.personal.importRawKey('138cbbfb21686ddc3b5ffeb2cfc83491175af68319977acb81d0ae93392c626c', '')

    // if unlock failed, may be is geth new version need to add --allow-insecure-unlock 
    console.log('>> Unlocking account ' + config.from);
    // //web3.personal.unlockAccount(config.from, process.env.ACCOUNT_PASSWORD, 36000);
    web3.eth.personal.unlockAccount(config.from, '', 36000);
  //}

  console.log('>> Deploying migration');

  deployer.deploy(Migrations);
};


truffle migrate


4. run

truffle test

Why you need to do this, because you can run many test (open 3 or more command line run truffle test) on same time for test your private poa ethereum.

If see Error, next step.


5. modify test/metacoin.js check code like this:


const MetaCoin = artifacts.require("MetaCoin");

Check accounts who have coin then change balance 0 or 1 & account one or two.

contract('MetaCoin', (accounts) => {
  it('should put 10000 MetaCoin in the first account', async () => {
    const metaCoinInstance = await MetaCoin.deployed();
    console.log('\n accounts: %o\n', accounts);
    
    const balance0 = await metaCoinInstance.getBalance.call(accounts[0]);
    const balance1 = await metaCoinInstance.getBalance.call(accounts[1]);
    console.log('balance0: %s', balance0.valueOf());
    console.log('balance1: %s\n', balance1.valueOf());

    assert.equal(balance1.valueOf(), 10000, "10000 wasn't in the first account");
  });
  it('should call a function that depends on a linked library', async () => {
    const metaCoinInstance = await MetaCoin.deployed();
    const metaCoinBalance = (await metaCoinInstance.getBalance.call(accounts[0])).toNumber();
    const metaCoinEthBalance = (await metaCoinInstance.getBalanceInEth.call(accounts[0])).toNumber();

    assert.equal(metaCoinEthBalance, 2 * metaCoinBalance, 'Library function returned unexpected function, linkage may be broken');
  });
  it('should send coin correctly', async () => {
    const metaCoinInstance = await MetaCoin.deployed();

    // Setup 2 accounts.
    const accountOne = accounts[1];
    const accountTwo = accounts[0];

    // Get initial balances of first and second account.
    const accountOneStartingBalance = (await metaCoinInstance.getBalance.call(accountOne)).toNumber();
    const accountTwoStartingBalance = (await metaCoinInstance.getBalance.call(accountTwo)).toNumber();

    // Make transaction from first account to second.
    const amount = 10;
    await metaCoinInstance.sendCoin(accountTwo, amount, { from: accountOne });

    // Get balances of first and second account after the transactions.
    const accountOneEndingBalance = (await metaCoinInstance.getBalance.call(accountOne)).toNumber();
    const accountTwoEndingBalance = (await metaCoinInstance.getBalance.call(accountTwo)).toNumber();


    assert.equal(accountOneEndingBalance, accountOneStartingBalance - amount, "Amount wasn't correctly taken from the sender");
    assert.equal(accountTwoEndingBalance, accountTwoStartingBalance + amount, "Amount wasn't correctly sent to the receiver");
  });
});


===========

web3 private key unlock & create contract


createcontract.js methond 1

var fs  = require('fs');

var Web3 = require("web3");
var provider = new Web3.providers.HttpProvider("http://192.168.99.100:18545");
var web3 = new Web3(provider);

console.log("before web set account: %o", web3.eth.defaultAccount);
const privateKey = 'd05bd152f3d71ff5f91830f3ccc1090fb670c7026ebf8c2136d4e5090d59398d';
const account = web3.eth.accounts.privateKeyToAccount('0x' + privateKey);
web3.eth.accounts.wallet.add(account);
console.log("private key import to account: %o", account)
web3.eth.defaultAccount = account.address;

try {
    web3.eth.personal.unlockAccount(account.address, "").then(console.log('Account unlocked!'));
} catch (err) {
    console.error('web3 unlockAccount Error: %o', err);
}

var certjson;
var certjsonpath = './Cert.json';

try {
    certjson = JSON.parse(fs.readFileSync(certjsonpath));
} catch (err) {
    console.error('readFileSync Error: %o', err);
}

const certContract = new web3.eth.Contract(certjson.abi);
certContract.options.data = certjson.bytecode;
certContract.options.from = '0x5921a4C1B13afbD4b61d63e9c7BD47741C47B176'
certContract.options.gas = '4700000'

console.log("web3 version: %o", web3.version)
web3.eth.getAccounts().then(o=>{console.log("Accounts: %o", o)})

certContract.deploy().send()
.on('error', (error) => {
    console.log("error: %o", error)
})
.on('transactionHash', (transactionHash) => {
    console.log("transactionHash: %o", transactionHash)
})
.on('receipt', (receipt) => {
    // receipt will contain deployed contract address
    console.log("receipt: %o", receipt)
    console.log("receipt.contractAddress: %o", receipt.contractAddress) 
})
.on('confirmation', (confirmationNumber, receipt) => {
    console.log("confirmationNumber: %o", confirmationNumber)
    console.log("confirmation receipt: %o", receipt)
})
.then(function(newContractInstance){
    if (typeof newContractInstance.options.address !== 'undefined') {
        console.log('Contract mined! address: ' + newContractInstance.options.address);
    }else{
        console.log("newContractInstance.address is undefined!")
    }
});

createcontract.js methond 2

var fs  = require('fs');

var Web3 = require("web3");
var provider = new Web3.providers.HttpProvider("http://192.168.99.100:18545");
var web3 = new Web3(provider);

console.log("before web set account: %o", web3.eth.defaultAccount);
const privateKey = 'd05bd152f3d71ff5f91830f3ccc1090fb670c7026ebf8c2136d4e5090d59398d';
const account = web3.eth.accounts.privateKeyToAccount('0x' + privateKey);
web3.eth.accounts.wallet.add(account);
console.log("private key import to account: %o", account)
web3.eth.defaultAccount = account.address;

try {
    web3.eth.personal.unlockAccount(account.address, "").then(console.log('Account unlocked!'));
} catch (err) {
    console.error('web3 unlockAccount Error: %o', err);
}

var certjson;
var certjsonpath = './Cert.json';

try {
    certjson = JSON.parse(fs.readFileSync(certjsonpath));
} catch (err) {
    console.error('readFileSync Error: %o', err);
}

const certContract = new web3.eth.Contract(certjson.abi);
certContract.options.data = certjson.bytecode;
certContract.options.from = '0x5921a4C1B13afbD4b61d63e9c7BD47741C47B176'
certContract.options.gas = '4700000'

console.log("web3 version: %o", web3.version)
web3.eth.getAccounts().then(o=>{console.log("Accounts: %o", o)})

// 怖署合約
var TxHash;

console.log("######## promise all ##############");

const getNonce = () => {
    return new Promise((resolve, reject) => {
        web3.eth.getTransactionCount(web3.eth.defaultAccount, (error, result) => {
            if(error) reject(error);
            resolve(web3.utils.toHex(result));
        })
    })
}

const getGasPrice = () => {
    return new Promise((resolve, reject) => {
        web3.eth.getGasPrice((error, result) => {
            if(error) reject(error);
            resolve(web3.utils.toHex(result));
        })
    })
}

// const sendRawTransaction = (rawTx) => {
//     const privateKey = "d05bd152f3d71ff5f91830f3ccc1090fb670c7026ebf8c2136d4e5090d59398d";
//     const tx = new Tx(rawTx);
//     const privateKeyBuffer = Buffer.from(privateKey, 'hex');
//     tx.sign(privateKeyBuffer);
//     const serializedTx = tx.serialize();
//     web3.eth.sendRawTransaction('0x' + serializedTx.toString('hex'), function(err, hash) {
//         console.log('Error:', err);
//         console.log('Hash:', hash);
//     });
// }
  
Promise.all([getNonce(), getGasPrice()]).then(values => {
    // const rawTx = {
    //     to: '0x203D17B4a1725E001426b7Ab3193E6657b0dBcc6',
    //     gasLimit: web3.toHex(1000000),
    //     value: web3.toHex(web3.toWei('0.1', 'ether')),
    //     nonce: values[0],
    //     gasPrice: values[1]
    // };
    // console.log(rawTx);
    // return(rawTx);

       console.log("nonce: %s", web3.utils.hexToNumber(values[0]));
       console.log("GasPrice: %s", web3.utils.hexToNumber(values[1]));

       web3.eth.estimateGas({from: "0x5921a4C1B13afbD4b61d63e9c7BD47741C47B176",data: contractjson.bytecode.object}).then(o=>{console.log("estimateGas: %o", o);})

    web3.eth.sendTransaction({
        from: "0x5921a4C1B13afbD4b61d63e9c7BD47741C47B176", // web3.eth.coinbase,  // web3.eth.getAccounts() 第一筆
        data: certjson.bytecode,
        nonce: values[0],
        gasPrice: values[1],
        gas: 4700000
    }).then(o=>{
        console.log("txhash object: %o", o); 
        TxHash = o.transactionHash;
        console.log("TxHash: %o", TxHash)
    
        web3.eth.getTransactionReceipt(TxHash).then(o=>{
            console.log("check contractAddress object: %s", o.contractAddress); 
        });    
    })
    .catch(e => console.log("sendTransaction error: %o", e));
})
.then(console.log("create transaction ok!"))
.catch(e => console.log("promise all error: %o", e))


node createcontract.js


===========
every 10sec create contract

First: fixed contract



pragma solidity >=0.4.25 <0.7.0;


contract MetaCoin {
 mapping (address => uint) balances;

 event Transfer(address indexed _from, address indexed _to, uint256 _value);

 constructor() public {
  balances[msg.sender] = 10000;
 }

 function sendCoin(address receiver, uint amount) public returns(bool sufficient) {
  if (balances[msg.sender] < amount) return false;
  balances[msg.sender] -= amount;
  balances[receiver] += amount;
  emit Transfer(msg.sender, receiver, amount);
  return true;
 }

 function getBalance(address addr) public view returns(uint) {
  return balances[addr];
 }
}

Promise.all method & web3.eth.sendTransaction


var fs  = require('fs');

var Web3 = require("web3");
var provider = new Web3.providers.HttpProvider("http://192.168.99.100:18545");
var web3 = new Web3(provider);

console.log("before web set account: %o", web3.eth.defaultAccount);
const privateKey = '138cbbfb21686ddc3b5ffeb2cfc83491175af68319977acb81d0ae93392c626c';
const account = web3.eth.accounts.privateKeyToAccount('0x' + privateKey);
web3.eth.accounts.wallet.add(account);
console.log("private key import to account: %o", account.address)
web3.eth.defaultAccount = account.address;

try {
    web3.eth.personal.unlockAccount(account.address, "").then(console.log('Account unlocked!'));
} catch (err) {
    console.error('web3 unlockAccount Error: %o', err);
}

var contractjson;
var contractjsonpath = './MetaCoin.json';

try {
    contractjson = JSON.parse(fs.readFileSync(contractjsonpath));
} catch (err) {
    console.error('readFileSync Error: %o', err);
}

const getNonce = () => {
    return new Promise((resolve, reject) => {
        web3.eth.getTransactionCount(web3.eth.defaultAccount, (error, result) => {
            if(error) reject(error);
            resolve(web3.utils.toHex(result));
        })
    })
}

const getGasPrice = () => {
    return new Promise((resolve, reject) => {
        web3.eth.getGasPrice((error, result) => {
            if(error) reject(error);
            resolve(web3.utils.toHex(result));
        })
    })
}

Promise.all([getNonce(), getGasPrice()]).then(values => {
    console.log("values: Nonce %s  GasPrice %s", web3.utils.hexToNumber(values[0]), web3.utils.hexToNumber(values[1]));
}).then(console.log("create transaction ok!"))
.catch(e => console.log("promise all error: %o", e))

setInterval( () => {

Promise.all([getNonce(), getGasPrice()]).then(values => {
    console.log("nonce: %s", web3.utils.hexToNumber(values[0]));
    console.log("GasPrice: %s", web3.utils.hexToNumber(values[1]));
   
   web3.eth.estimateGas({from: "e79d33e93bd888b35e055f1a12d876354729037b",data: contractjson.bytecode.object}).then(o=>{console.log("estimateGas: %o", o);})

    web3.eth.sendTransaction({
        from: "e79d33e93bd888b35e055f1a12d876354729037b", // web3.eth.coinbase,  // web3.eth.getAccounts() 第一筆
        data: contractjson.bytecode.object,
        nonce: values[0],
        gasPrice: 20000000000, //20,000,000,000
        gas: 181949 //181,949
    }).then(o=>{
        console.log("txhash object: %o", o); 
        TxHash = o.transactionHash;
        console.log("TxHash: %o", TxHash)
    
        web3.eth.getTransactionReceipt(TxHash).then(o=>{
            console.log("check contractAddress object: %s", o.contractAddress); 
        });    
    })
    .catch(e => console.log("sendTransaction error: %o", e.message));
})
.then(console.log("create transaction ok!"))
.catch(e => console.log("promise all error: %o", e.message))

}, Math.random() * 10000);


every 5sec create contract & web3 contract method


var fs  = require('fs');

var Web3 = require("web3");
var provider = new Web3.providers.HttpProvider("http://192.168.99.100:18545");
var web3 = new Web3(provider);

console.log("before web set account: %o", web3.eth.defaultAccount);
const privateKey = '138cbbfb21686ddc3b5ffeb2cfc83491175af68319977acb81d0ae93392c626c';
const account = web3.eth.accounts.privateKeyToAccount('0x' + privateKey);
web3.eth.accounts.wallet.add(account);
console.log("private key import to account: %o", account.address)
web3.eth.defaultAccount = account.address;

try {
    web3.eth.personal.unlockAccount(account.address, "").then(console.log('Account unlocked!'));
} catch (err) {
    console.error('web3 unlockAccount Error: %o', err);
}

var contractjson;
var contractjsonpath = './MetaCoin.json';

try {
    contractjson = JSON.parse(fs.readFileSync(contractjsonpath));
} catch (err) {
    console.error('readFileSync Error: %o', err);
}

setInterval( () => {

contractAddr = "0x46Fac13Ca8398545479bF2DA18133Aa87377b559";
contractfrom = "0xe79d33e93bd888b35e055f1a12d876354729037b";
coinOwnerAddr = "0xe79d33e93bd888b35e055f1a12d876354729037b"
sendCointoAddr = "0x5921a4C1B13afbD4b61d63e9c7BD47741C47B176";

var metacoinContract = new web3.eth.Contract(contractjson.abi, contractAddr);

metaCoinContract.methods.getBalance(coinOwnerAddr).call({
    from: contractfrom,
    gasPrice: 20000000000, //20,000,000,000
    gas: 181949
})
.then(o=>{console.log(coinOwnerAddr+" getBalance: %o", o)});

metaCoinContract.methods.sendCoin(sendCointoAddr, 10).send({
    from: contractfrom,
    gasPrice: 20000000000, //20,000,000,000
    gas: 181949
})
.then(o=>{console.log("sendCoin: %o", o)});

metaCoinContract.methods.getBalance(sendCointoAddr).call({
    from: contractfrom,
    gasPrice: 20000000000, //20,000,000,000
    gas: 181949
})
.then(o=>{console.log(sendCointoAddr+" getBalance: %o", o)});

}, Math.random() * 5000);

// .on('transactionHash', function(transactionHash){
//     console.log("transactionHash: %o", transactionHash)
// })
// .on('receipt', function(receipt){
//     console.log("receipt: %o", receipt)
//     console.log("receipt.contractAddress: %o", receipt.contractAddress) 
// })
// .on('confirmation', function(confirmationNumber, receipt){
//     console.log("confirmationNumber: %o", confirmationNumber)
//     console.log("confirmation receipt: %o", receipt)
// })
// .on('error', function(error){console.log("error: %o", error.message)});


=====
https://medium.com/finnovate-io/how-do-i-sign-transactions-with-web3-f90a853904a2
https://ethereum.stackexchange.com/questions/60611/defining-the-transaction-object-for-offline-transaction-signing-using-web3-js-f
https://github.com/ethereum/web3.js/issues/1430

https://programtheblockchain.com/posts/

Architecture Behind Sila Ethereum Transactions

https://silamoney.com/2019/07/08/using-aws-lambda-sqs-with-web3/
https://silamoney.com/2019/07/08/using-aws-lambda-sqs-with-web3-2/



Major components

  1. DynamoDB to store the nonce associated with ethereum addresses authorized to send ethereum smart contract transactions
  2. Lambda functions triggered by SQS events for SilaToken issuance, redemption, and transfer messages
  3. Ethereum RPC EC2 servers running Parity Ethereum client
  4. AWS Secrets Manager to store private keys being used to sign the transactions
  5. Orchestrator as a bridge between REST API, ACH, and ethereum transactions. Orchestrator is a piece of code that handles the transaction state and reroutes them to right queue.
  6. SQS as an interface between different services like REST API, ACH, Ethereum issuance, redemption, and transfers.


Transaction Lifecycle

Messages for SilaToken issuance, redemption, and transfer comes in through Sila APIs. Dependent on the action (issue, redeem, and transfer), the message is sent to the relevant queue by Orchestrator, which in turn triggers the send transaction Lambda function.
That sends the transaction, signed by Sila’s authorized address, to Ethereum node and increases the nonce in the database by one, for subsequent transactions. The message is deleted from the ethereum transaction queue and sent to the ethereum pending queue with the transaction hash and nonce, then sent with the block number appended in the message history. Replace and check for transaction send failure if there is a bad RPC connection.

play around with sila api

Constructing a Transaction:

constructing transaction

Sending a transaction:

AWS Lambda SQS Fintech

Nonce management

After experimenting with several ways to manage the authorized address nonce we settled on storing it in a database, as it is faster to retrieve and update there than making a Web3 call to the RPC server and waiting for the transaction to be mined. It has its pitfalls, however. For example, subsequent transactions can get stuck until previous transactions have been mined, but that’s why we have three Lambda functions that are watching just the pending transactions — and we’ll discuss how to handle pending ethereum smart contract transactions in the next section.
Nonce management is not as straightforward, as we have three Lambda functions that can send transactions. In our case we have conditions in place that are dependent on message history.

Deciding gas price & gas limit

Gas limit is set based on the amount of computation involved in the smart contract function call. However we can play around with the gas price to make sure transactions are being mined in the desired time. We use a modified version of eth_gas_station engine to decide the gas price, based on the network mining requirements.

Handling Transactions in Pending Queue

Let’s dive deeper into the three Lambda functions that are watching the pending queue . . .

1. Check pending transactions for success or a fail

Previously we discussed how we appended the tx_hash, nonce and sent_at_blockNumber in the message history, we use tx_hash and web3 module to get the transaction status. The transaction status can be 0,1, or null depending on if the transaction has been mined successfully. Status 0 and 1 both result in a nonce increment for the authorized address, as the transaction was mined in some block. If the status is 0, which means the transaction failed, we retry the transaction by sending it back to the transaction queue. Each transaction is restricted to a maximum of 3 retries, after which it is dumped into Orchestrator. If the status is 1 which means that the transaction was successful, a message with success update is sent to Orchestrator.

2. Replacing stuck transactions

If the transaction hash gets a null and transaction has been pending in the node memory pool for a long time, consider how we appended the sent_at_block number and nonce in the message history. We get the current block number, using Web3, and compare the difference; if the difference is more than 80 blocks (and the difference can be set to higher or lower), which means the transaction has been pending for 80 blocks, we replace the transaction with a higher gas price, keeping the nonce value the same as in the message.

3. Handling transaction send failures

If you play with Ethereum long enough you will have certain cases where you are unable to find the sent transaction in the node memory pool. This means the transaction never hit the Ethereum RPC server, but we have another Lambda function that will redirect the transaction message to the queue.

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About Sila
Sila provides Banking and Payments Infrastructure-as-a-Service for teams building the next generation of financial products and services. Our banking API replaces the need for integrating with legacy financial institutions saving you months of development time and thousands in legal and regulatory expenses.

haproxy failover backup server

https://www.haproxy.com/blog/failover-and-worst-case-management-with-haproxy/


Normal backup servers: In this case, s3 will be used first, until it fails, then s4 will be used.



frontent ft_app
 bind 10.0.0.1:80
 default_backend bk_app_main
backend bk_app_main
 server s1 10.0.0.101:80 check
 server s2 10.0.0.102:80 check
 server s3 10.0.0.103:80 check backup
 server s4 10.0.0.104:80 check backup


Multiple backup servers: In this case, both s3 and s4 will be used if they are available.

option allbackups



frontent ft_app
 bind 10.0.0.1:80
 default_backend bk_app_main
backend bk_app_main
 option allbackups
 server s1 10.0.0.101:80 check
 server s2 10.0.0.102:80 check
 server s3 10.0.0.103:80 check backup
 server s4 10.0.0.104:80 check backup

nginx failover without load balancing

https://serverfault.com/questions/480241/nginx-failover-without-load-balancing


pstream backend {
    server 1.2.3.4:80 fail_timeout=5s max_fails=3;
    server 4.5.6.7:80 backup;
}

server {
    listen 80;
    server_name whatevs.com;

    location / {
        proxy_pass http://backend;
    }
}


https://www.cnblogs.com/biglittleant/p/8979887.html

backup 预留的备份服务器,当其他所有的非backup服务器出现故障或者忙的时候,才会请求backup机器,因为这台集群的压力最小。

max_fails 允许请求失败的次数,默认是1,当超过最大次数时,返回proxy_next_upstream模块定义的错误。0表示禁止失败尝试,企业场景:2-3.京东1次,蓝汛10次,根据业务需求去配置。

fail_timeout,在经历了max_fails次失败后,暂停服务的时间。京东是3s,蓝汛是3s,根据业务需求配置。常规业务2-3秒合理。

例:如果max_fails是5,他就检测5次,如果五次都是502.那么,他就会根据fail_timeout 的值,等待10秒,再去检测。


https://blog.51cto.com/wangwei007/1103727

ethereum Nonce collisions

https://hackernoon.com/ethereum-blockchain-in-a-real-project-with-500k-users-f85ee4821b12

Nonce collisions
Nonce collisions were another mysterious thing we’ve encountered when trying to scale the number of Geth nodes in order to cover the case when one node crashes. It turns out that


We used a simple load balancer before the three Geth nodes, which was sending each transaction to one of the three nodes. The problem was that each time we submitted many transactions at once, some of those transactions were mysteriously disappearing. It took a day or two until we finally figured out that this was a problem with nonce collisions.

When you are submitting raw transactions to the network you are fine, because you keep track of nonce numbers yourself. In this case you just need a node to publish raw transactions to the network. But in the case you are using an account unlocking mechanism built into the node and do not specify the nonce when publishing transactions (with web3 or so), the node tries to pick the appropriate nonce value itself and then signs a transaction.

Because of the network delays, in the case two nodes receive the same transaction publishing request, they can generate the same nonce value. At the moment of receiving the transaction publishing request they don’t know that they both received a transaction with the same nonce. Thus, when propagating these transactions through the network, one of them will eventually be dropped because its “transaction nonce is too low”.

To fix nonce collisions introduced by adding a load balancer to a system, we needed to create a different kind of load balancer. For example, a load balancer which always uses one particular node and switches to another node only if the first one is down.

ethereum Proper Transaction Signing nonce

https://ethereum.stackexchange.com/questions/12823/proper-transaction-signing


const Web3 = require('web3');
const Tx = require('ethereumjs-tx');
const config = require('./config');

const web3 = new Web3(new Web3.providers.HttpProvider(config.provider)); //link provided by Infura.io
web3.eth.defaultAccount = "0xc929c890f1398d5c1ecdf4f9ecec016906ac9f7f";

const getNonce = () => {
  return new Promise((resolve, reject) => {
    web3.eth.getTransactionCount(web3.eth.defaultAccount, (error, result) => {
      if(error) reject(error);
      resolve(web3.toHex(result));
    })
  })
}
const getGasPrice = () => {
  return new Promise((resolve, reject) => {
    web3.eth.getGasPrice((error, result) => {
      if(error) reject(error);
      resolve(web3.toHex(result.toNumber()));
    })
  })
}

const sendRawTransaction = (rawTx) => {
  const privateKey = "190b820c2627f26fd1b973b72dcba78ff677ca4395c64a4a2d0f4ef8de36883c";
  const tx = new Tx(rawTx);
  const privateKeyBuffer = Buffer.from(privateKey, 'hex');
  tx.sign(privateKeyBuffer);
  const serializedTx = tx.serialize();
  web3.eth.sendRawTransaction('0x' + serializedTx.toString('hex'), function(err, hash) {
      console.log('Error:', err);
      console.log('Hash:', hash);
  });
}

Promise.all([getNonce(), getGasPrice()])
  .then(values => {
    const rawTx = {
      to: '0x203D17B4a1725E001426b7Ab3193E6657b0dBcc6',
      gasLimit: web3.toHex(1000000),
      value: web3.toHex(web3.toWei('0.1', 'ether')),
      nonce: values[0],
      gasPrice: values[1]
    };
    console.log(rawTx);
    return(rawTx);
  })
  .then(sendRawTransaction)
  .catch(e => console.log(e))

ring buffer

https://zhen.org/blog/ring-buffer-variable-length-low-latency-disruptor-style/

https://github.com/smartystreets-prototypes/go-disruptor

ethereum transaction template

https://ethereum.stackexchange.com/questions/50042/why-does-sendsignedtransaction-return-a-tx-hash-but-does-not-post-to-the-rinkeby


window.web3 = new Web3(new Web3.providers.HttpProvider(endpoint));

sendEther() {
    const fromAccount = **acct1**;
    const toAccount   = **acct2**;

    const rawTransaction    = this.makeRawTransaction(fromAccount, toAccount);
    const signedTransaction = this.makeSignedTransaction(rawTransaction);
    const serializedTransaction = `0x${signedTransaction.serialize().toString('hex')}`;

    window.web3.eth.sendSignedTransaction(serializedTransaction, (error, result) => {
        if(!error) {
          console.log(`Transaction hash is: ${result}`);
          this.setState({
            etherscanUrl: `https://rinkeby.etherscan.io/tx/${result}`,
            error: null
          });

        } else {
          this.setState({ error: error.message })
          console.error(error);
        }
    });
  }

  makeSignedTransaction(rawTransaction) {
    const privateKey   = '**************';
    const privateKeyX  = new Buffer(privateKey, 'hex');
    const transaction  = new EthTx(rawTransaction);
    transaction.sign(privateKeyX);

    return transaction;
  }

  makeRawTransaction(fromAccount, toAccount) {
    const { exchangeRate } = this.props;
    const amount = (1 / exchangeRate) * 5;

    return ({
      nonce: window.web3.utils.toHex(window.web3.eth.getTransactionCount(fromAccount)),
      to: toAccount,
      gasPrice: window.web3.utils.toHex(100000000000),
      gasLimit: window.web3.utils.toHex(100000),
      value: window.web3.utils.toHex(window.web3.utils.toWei(`${amount}`, 'ether')),
      data: ''
    });
  }

[轉]Windows、WSL 与 Linux 的性能对比

https://www.cnbeta.com/articles/tech/922349.htm

尽管执行了各种各样的测试,但是如果对在七个不同操作系统上成功运行的所有测试取几何平均值,可以得出这样的结论:

Windows 10 Build 19008 的总体性能要比 Build 18362 版本好,而 WSL 的性能并没有太大变化

WSL2 比 WSL 的性能确实稍好一些,这是因为在 I/O 或网络活动繁重的工作负载的情况下前者性能要好得多

在这种特殊的 Core i9 7960X 场景下,运行 Ubuntu Linux 的速度总体上比最快的 Windows 配置快 27%

有兴趣的朋友可查看这份更详细的 OpenBenchmarking.org 结果文件,以深入研究这些 Windows / WSL / Linux 基准测试内容。

geth attach



geth --exec "eth.blockNumber" attach --datadir ./
geth --exec "eth.syncing" attach --datadir ./
geth --exec "admin.peers" attach --datadir ./
geth --exec "clique.getSnapshot()" attach --datadir ./

watch -n 2 'geth --exec "clique.getSnapshot()" attach --datadir ./'

geth-prometheus

https://github.com/karalabe/geth-prometheus


https://blog.ethereum.org/2019/07/10/geth-v1-9-0/

You can quickly reproduce the above charts via my clone of Maxim Krasilnikov’s project by running docker-compose up in the repo root and accessing http://localhost:3000 with the admin/admin credentials. Alternatively, you can view my testing snapshot on Raintank, or import this dashboard into your own Grafana instance

源碼掃瞄

Checkmarx
Fortify

ethereum geth check transaction

geth console


## get balance

eth.getTransaction("")
eth.getTransactionReceipt("")

EX: transaction id 0x8dfaa1b5d2e660ee2d3aa9fd0eeb33cc726d50122790e882a914ffd7d02e3a83
eth.getTransaction("0x8dfaa1b5d2e660ee2d3aa9fd0eeb33cc726d50122790e882a914ffd7d02e3a83")
eth.getTransactionReceipt("0x8dfaa1b5d2e660ee2d3aa9fd0eeb33cc726d50122790e882a914ffd7d02e3a83")


## get transaction count

eth.getTransactionCount()
eth.getTransactionCount(, "pending")

EX: transaction id 0x8dfaa1b5d2e660ee2d3aa9fd0eeb33cc726d50122790e882a914ffd7d02e3a83
eth.getTransactionCount("0x8dfaa1b5d2e660ee2d3aa9fd0eeb33cc726d50122790e882a914ffd7d02e3a83")
eth.getTransactionCount("0x8dfaa1b5d2e660ee2d3aa9fd0eeb33cc726d50122790e882a914ffd7d02e3a83", "pending")


## check pending queued

txpool.status

EX:
{
pending: 0,
queued: 5
}

融資

目前好像國泰比較優
年利率2% 手續費2千
一年到期續約不用手續費
這些都是基本條件不需要談

對啊,不過國泰大概是給年薪的3倍額度

年薪50萬,就150萬

聯邦18個月後,要還一次本金嗎?
聯邦不用還本金
國泰也不用


所以500萬,屆滿300萬,18個月後,直接續新約齁?

銀行、證券金融,國泰、聯邦、元大證金,就沒這種規定

查驗 驗收

.需求書內 合約 改成 契約

勞務請購 準備文件
1. 購案核定清單
2. 自我檢核表
3. 報價單
4. 需求書
5. 承攬商 (有派人力到 中心/公司 工作情況)
最後 預估金額分析表 (簽核過財會後,請購人員會給予後填寫)

案子的負責「採購人員」是: AAA
先請試填請購單後,截取畫面併相關文件給採購人員確認是否正確後,再正式填寫請購單
會科問題 BBB 會計人員

金額比例 300 200 (依期數 如這裡500 分二期)
需求書上 兩次:10/30、6/31
付款注意:年底可能會關帳,要提前,建議一個月為主

特別注意:查驗和驗收不同,案子通常第一期為查驗,第二期為驗收,兩者皆為組長(負責主管),如沒空,可找代理人,查驗/驗收需求項目、文件順序需按照需求書

第一期查驗:
.我方需要確認資料、系統和文件是否正確,系統檔案可存放光碟(建議全放)
.查驗文件依需求書需求項目為主,再說明查驗或驗收順序已備齊
.廠商準備現場DEMO及列印文件,務必提前一到二星期準備
.另廠商需寄送EMail告知開發完畢,可進行查驗或驗收,印該EMail代表收到開發完畢文件
.查驗文件上的完成覆約日期為收到EMail為主,查驗測試時間則為實際排定查驗測試日期

第二期驗收:
.需先再跑查驗流程(非第一期查驗),再驗收
.需自行把系統自行跑過一次,代表有實際確認過
.其他同第一期
.查驗過後,將相關資料給予採購人員,會協助安排組長驗收時間,自行安排會議室
.驗收記錄給予廠商,進行發票開立作業
.收到廠商發票後交給採購人員

[轉]Flutter 状态管理指南之 Provider

https://zhuanlan.zhihu.com/p/70280813

[轉]Flutter 全局状态管理之 Provider 初探

https://juejin.im/post/5d8f324ee51d45781e0f5dca

一、什么是全局状态管理

当我们在使用 Flutter 进行应用开发时,可能需要不同的页面共享应用或者说变量的状态,当这个状态发生改变时,所有依赖这个状态的 ui 都会随之发生改变。在同一个页面中还好说,直接通过 setState 就可以达到目的,要是不同的页面呢,或者当应用变得非常复杂,页面非常多的时候,这个时候全局状态管理就显得非常重要了。
在 Flutter 中,状态管理可以有如下几种方式:
1、setState
flutter 中最简单使 ui 根据状态发生改变的方式。
2、 InheritedWidget & InheritedModel
InheritedWidget 和 InheritedModel 是 flutter 原生提供的状态管理解决方案。 当InheritedWidget发生变化时,它的子树中所有依赖了它的数据的Widget都会进行rebuild,这使得开发者省去了维护数据同步逻辑的麻烦。
3、Provider & Scoped Model
Provider 与 Scoped Model 都属于第三方库,两者使用起来差不多,其中 Provider 是 Google I/O 2019 大会上官方推荐的状态管理方式。
4、Redux
在 Redux 状态管理中,所有的状态都储存在Store里,Flutter 中的 Widget 会根据这个 Store 去渲染视图,而状态的改变也是通过 Reduex 里面的 action 来进行的。
5、BLoC / Rx
BLoC的全称是 业务逻辑组件(Business Logic Component)。就是用reactive programming方式构建应用,一个由流构成的完全异步的世界。 BLoc 可以看作是 Flutter 中的异步事件总线,当然在除了 BLoc 外,Flutter 中有专门的响应式编程库,就是RxDart,RxDart是基于ReactiveX标准API的Dart版本实现,由Dart标准库中Stream扩展而成。

作者:Flutter编程开发
链接:https://juejin.im/post/5d8f324ee51d45781e0f5dca
来源:掘金
著作权归作者所有。商业转载请联系作者获得授权,非商业转载请注明出处。

[轉]如何選擇ERP

https://www.ptt.cc/bbs/MIS/M.1575624725.A.74A.html

: 各位前輩大家好
: 小弟目前被賦予任務如下:
: 評估各家ERP優缺並負責導入相關事宜
: 我司產業為製造業(女鞋代工),產品皆外銷
: 主要需要解決的問題為以下:
: 1.BOM數位化問題
: 2.訂單轉換採購單,備料單重工問題
: 預算目前沒有上限;
: 從未導入過任何ERP系統,截至目前為止皆為人工手KEY各種報表;
: 目前已接觸過鼎新,尚揚,鴻來軟件
: 請問各位前輩還有推薦的ERP廠商嗎?

原提問人已經「面談」過不少軟體商的業務人員,為何還來這裡徵求各界意見?

其實,聽取軟體商簡報後,仍陷入「一頭霧水」狀態的MIS主管,我曾經就是其中一員,彼岸更多!

這個提問觸發我寫下一篇文章《如何選擇ERP》。先預熱一下...

恰巧我曾經任職一家只幫愛迪達代工,18000人的廣東鞋廠,厚顏擔任只出一張嘴「管理」28名部屬的MIS部門最高主管(經理)。

該廠當時:廣東有相距近百公里之遙的2個工廠、臺中辦公室、積極動工中的印度工廠。

除了HR當然有的考勤、薪資業務之外,有員工(收費、補助)餐廳、保險、住宿...等資訊需求。

入職當時,該廠正積極汰換ERP軟體,鄙人立即展開「ERP選型」工作。

接手之前,已經有下列軟體商爭取那門生意:

- SAP的「鞋服solution」
- 金蝶
- 深圳的中X(老闆已改行,偶有聯絡。)
- 高雄的先濬

我的調查方式:製作問卷,列舉技術問題,邀請軟體商答題。

按我的記憶列舉一、二:

1. 軟體能否「同時」處理「品名」和「尺碼」?所謂「處理」,包括:跑MRP、追蹤和紀錄各「品名」和「尺碼」的成本與數量。

2. 軟體能否處理各材料的保稅(出口退稅)功能?

3. 軟體能否線上切換語系?(希望印度廠也能使用)

4. 資訊人員能否設計一份報表,中國廠職員使用簡體字打印、臺中廠職員使用正體字打印、印度職員使用英文打印?

5. 資訊人員每設計一份報表之後,是否必須分別在中國廠的800部電腦安裝、去印度廠安裝、去臺中辦公室安裝?(「安裝」包括遠程分發、自動下載並安裝package)

6. 軟體系統使用何種程式語言設計?(事涉MIS人員接手維護軟體的學習曲線、求才難易度、薪資水準)

7. 軟體使用何種資料庫管理系統?(影響老闆的錢包)

8. 會計月結,是否必須來回嘗試幾次過帳、反過帳、結帳、反結帳,可能失敗、出現「負庫存量」、「負金額」?

9. 軟體能否「隨時」顯示「品名」和「尺碼」的真實(不是「標準」)成本與數量,無須等到下月初的月結?

...

當時,

- 用過Tiptop,確定0分,所以懶得聯絡鼎新業務員。
- 知道SAP是垃圾,故直接忽略SAP,連問卷也不發給那些X子。
- 金蝶不繳交問卷,從此失聯。
- 中X答非所問、回答不完整,但是仍拜訪、打電話,積極爭取訂單。
- 先濬拒絕答題。

我當時最敬佩的軟體商是金蝶,因為他們躲起來,證明是唯一有羞恥心的業務員,他們不願意欺騙、說謊。

老闆無視我的反對,所以先濬拿到訂單。我離職後,老闆支付三分之一合約金(330萬元臺幣)後,先濬從此失聯。

我給原提問人能心安理得、睡好覺的建議:

1、參考我前述問卷內容以及下面的參考資料,製作一份問卷,發給全部軟體商,邀請他們答題。

2、邀請那些全部回答「yes」的廠商向你當面示範那些「yes」的軟體功能。

3、淘汰這些軟體商:回答不清楚、回答「no」、不敢示範那些「yes」的軟體功能。

4、從那些全部回答「yes」而且確實示範軟體功能真實不虛的軟體商之中,選擇報價最低的一家,直接推薦給老闆。

5、如果不幸證明全部檯面上的軟體商都是騙子的話,只好去我的SaaS官網免費註冊、試用,基於你的專業和敬業,回答你自己的問卷,並且相信自己的眼睛,而非耳朵。
手冊:https://terarows.gitlab.io/app2/

---參考資料---

http://www.itpub.net/thread-1892471-1-1.html

- 勞工:三班制:07:00 ~ 15:00、15:00 ~ 23:00、23:00 ~ 07:00。夜班提供夜點費。
- 遲到半小時內,扣薪N元。遲到M小時以上,視同請假半日。早退,(忘了詳情!)。未請假,曠職,扣薪X元。
- 有全勤獎。
- 小過:扣N元;大過,扣M元。小功:獎N元;大功,獎M元。
- 文員:高級主管不打卡,其餘須打卡。可填單報出差。
- 薪資:按層級表。也許有年終獎金。
- 年假/年資對照表。
- 外國勞工提供住宿。
- 中國廠有用餐制度、住房、保險。
- 台灣廠有勞保、健保、綜合所得扣繳憑單。
- 當然,打卡鐘24小時侍候。

多公司。在線切換,無須登出再登錄。

多國語言。在線切換,無須登出再登錄。

已翻譯正體中文、簡體中文、英文。按各種語言輸入料項目、供應商名、地址、人名..。

多時區。倫敦用戶輸入、顯示「2014-12-01 00:00:00 +0」,北京用戶輸入、顯示「2014-12-01
08:00:00 +8」。

支持料品批號、鞋子的尺碼、成衣的尺碼。

會計科目只有一段。
一些ERP要求:每一個料號指定一個多段會計科目編碼。例如:1111-00A-123。其中,「1111」代表『原料』、「00A」代表『00A部門』、「123」代表『123料號』。
PostERP只使用會計科目只有一段:「1111」,代表『原料』。

無縫整合會計:凡是與金額相關的交易,都轉拋會計分錄。會計人員的記帳工作趨近零。

會計分錄只有一個屏幕,無須多個屏幕來回翻找、比對、輸入。這個屏幕容納成本、供應商、客戶、應收帳款、應付帳款、銀行存摺帳號...等信息。

無須過帳、反過帳。結帳重點工作,只運行一個指令,處理:虛帳戶結轉實帳戶、本期實帳戶餘額復制成下期期初餘額。

支持先進先出、後進先出、移動加權平均成本。永續盤存制。

隨時反應每一個倉位中的每一個項目、每一個批號的最新成本,無須等到月結。

MRP同時考慮項目與批號(或尺碼):
1、需求數量(數量,時間)
2、倉庫現存可用量(數量)
3、BOM標準用量(數量)
4、BOM父項損耗率、子項損耗率(數量)
5、生產工藝(數量、時間)(目前從缺)
6、計劃單數量(數量,時間)
7、請購單數量(數量,時間)
8、採購單數量(數量,時間)
9、外包單數量(數量,時間)
10、生產單數量(數量,時間)
11、生產投料單數量(數量,時間)
12、生產記錄(數量、時間)
13、最小包裝量/不可分割數量(數量)
14、最低採購數量(數量)
15、最低生產批量/最低外包批量(數量)
16、時柵(時間)(目前從缺)
17、時格(時間)(目前從缺)
18、提前期(時間)

多層「一對多」單據。例如:在同一個屏幕的一張出貨單號含多種藥名,每個藥名含多個批號,每個批號含多個出貨日期,每個出貨日期含多個交貨目的地;自多個儲位撿貨。

各種語言在線求助:屏幕說明、字段說明、報表用途與參數說明、程序用途與參數說明。

備正體中文、簡體中文、英文文檔,供使用人以瀏覽器閱讀。

MIS人員在瘦客戶上面開發、修改、強化ERP,終端使用人在瘦客戶操作ERP。

瘦客戶內建報表引擎,無須外掛Crystal Report等:MIS人員設計報表樣板,終端使用人運行報表。100%整合在瘦客戶的menu中。

MIS人員設計的一份WYSIWYG報表樣板,台灣文員預覽或打印正體中文報表、中國廠員工人打印正體中文報表、印度user print英文report。可設計cross tab報表、含bar code報表、子報表(sub-report)。

伺服器軟件與瘦客戶之間的傳輸資料經過(1)加密(2)壓縮。不需要VPN、Citrix、Windows Remote Desktop。

提供類似Unix crontab的排程機制。

巨細靡遺記錄user的輸入、修改、刪除記錄。

每一筆記錄都允許附掛32767個文檔,例如:工程圖.png、標準作業程序說明.doc。

屏幕中的每一個table都允許匯出成文檔,供LibreOffice的Calc、M$ Excel等軟件匯入。



《不易聽到SAP專案失敗的原因》:
https://bit.ly/2DPkDZZ
https://bit.ly/2OOanYv

ethereum 交易 驗證

https://www.blocktempo.com/blockchain-technical-overview-structure-of-blockchain-ethereum/

3. 以私鑰簽署交易。
4. 廣播「加上簽名的交易封包」至鄰近的以太坊節點們。


https://ithelp.ithome.com.tw/m/articles/10215095

總而言之在區塊鏈接納這筆交易前,先試著用地址反推回原本的公鑰,再用公鑰解密當初這筆交易紀錄的簽章看看,如果公鑰解的開就可以代表是公鑰持有人本人所簽核的,這便是剛剛提到的"數位簽章"。
注意:這段比較像是一般加解密的方式,好像不是ethereum


https://ethereum.stackexchange.com/questions/13778/get-public-key-of-any-ethereum-account

ethereum 簽完的東西 可以 找出 public key
有public key 就可以知道是誰發出這個交易


https://zhuanlan.zhihu.com/p/30481292

签名完成了,我们如何验证某些签名后的数据是哪个账户签名的呢?在web3.js 发布1.0版本以前,验证签名只能通过智能合约的ecrecover函数来实现。新版的web3.js提供了web3.eth.accounts.recover函数用于验证签名。这里我们仍然使用传统的智能合约ecrecover方式。

ecrecover接收数据的哈希值以及r/s/v等参数作为输入,返回实施该签名的账户地址。因此我们只需要通过合约拿到实施签名的地址,和我们真正的地址进行对比,如果地址一致,就说明验证通过了。


這也是ethereum private key和address比較重要的原因了


https://learnblockchain.cn/books/geth/part3/sign-and-valid.html

linux .bashrc


# General Aliases
    alias apk='apk --progress'
    alias ll="ls -ltan"

    alias hosts='cat /etc/hosts'
    alias ..="cd .."
    alias ...="cd ../.."
    alias ....="cd ../../.."
    alias untar="tar xzvkf"
    alias mv="mv -nv"
    alias cp="cp -i"
    alias ip4="ip -4 addr"
    alias ip6="ip -6 addr"

    COL_YEL="\[\e[1;33m\]"
    COL_GRA="\[\e[0;37m\]"
    COL_WHI="\[\e[1;37m\]"
    COL_GRE="\[\e[1;32m\]"
    COL_RED="\[\e[1;31m\]"

    # Bash Prompt
    if test "$UID" -eq 0 ; then
        _COL_USER=$COL_RED
        _p=" #"
    else
        _COL_USER=$COL_GRE 
        _p=">"
    fi
    COLORIZED_PROMPT="${_COL_USER}\u${COL_WHI}@${COL_YEL}\h${COL_WHI}:\w${_p} \[\e[m\]"
    case $TERM in
        *term | rxvt | screen )
            PS1="${COLORIZED_PROMPT}\[\e]0;\u@\h:\w\007\]" ;;
        linux )
            PS1="${COLORIZED_PROMPT}" ;;
        * ) 
            PS1="\u@\h:\w${_p} " ;;
    esac

存股

https://www.youtube.com/watch?v=uqlUFvkyEUg

1. 折舊長 不能折舊短 代表長期經營
2. 能控制供應 多或少,像蘋果 有強大的控制供應能力,需求多不見得
3. 產品周期長

hyperledger leader peer endorsing peer committing peer

leader peer 是peer之間動態選舉選出的

endorsing peer 預設為每個peer都是,安裝chaincode後,實例化設定policy可以有變化

committing peer 預設為每個peer都是

https://medium.com/@kctheservant/transactions-in-hyperledger-fabric-50e068dda8a9
https://stackoverflow.com/questions/52893818/difference-between-endorsing-peer-and-committing-peer-in-hyperledger-fabric/52894994

kubernetes K3s Failed!

Failed reason: Node port range can't fixed!


K3s


##### install #####
curl -sfL https://get.k3s.io | sh -


##### login https://192.168.99.119:6443/ get username/password #####
more /etc/rancher/k3s/k3s.yaml


##### change node-port range #####
k3s server --kube-apiserver-arg --service-node-port-range=1-65535


##### install dashboard #####
k3s kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v1.10.1/src/deploy/recommended/kubernetes-dashboard.yaml --insecure-skip-tls-verify

k3s kubectl create secret generic kubernetes-dashboard-certs --from-file=certs -n kube-system

k3s kubectl apply -f dashboard-ClusterRoleBinding.yaml
k3s kubectl apply -f dashboard-adminuser.yaml
k3s kubectl -n kube-system describe secret $(kubectl -n kube-system get secret | grep admin-user | awk '{print $1}')

Find admin-user-token

https://192.168.99.119:30393/


##### kill all #####
k3s-killall.sh
k3s-uninstall.sh

##### start k3s service #####
service k3s status ## check k3s is stop
service k3s start

Replace uglifyjs-webpack-plugin with terser-webpack-plugin

https://github.com/vuejs/vue-cli/issues/2245

https://github.com/webpack-contrib/terser-webpack-plugin

https://stackoverflow.com/questions/57360588/how-to-use-terser-with-webpack

https://juejin.im/post/5cbc40ea6fb9a068b65e2aa6


npm install npm install terser-webpack-plugin

vue.config.js


const TerserPlugin = require('terser-webpack-plugin');

module.exports = {
    chainWebpack: process.env.NODE_ENV === 'production'
    ? config => {
        config.module.rules.delete('eslint');
        config.optimization.minimizer([
            new TerserPlugin({
                terserOptions: {
                    parse: {
                      ecma: 8
                    },
                    compress: {
                      ecma       : 5,
                      warnings   : false,
                      comparisons: false,
                      inline     : 2
                    },
                    mangle: {
                      reserved: ["BigInteger","ECPair","Point"],
                      safari10: true
                    },
                    output: {
                      ecma      : 5,
                      comments  : false,
                      ascii_only: true
                    }
                },
                cache: true,
                parallel: true,
                sourceMap: false, // false 可以減少一半的js大小,sourceMap為除錯使用
            })
        ]);
    }
    : config => {
        config.module.rules.delete('eslint');
    },
    devServer: {
        host: '0.0.0.0',
        port: '80',
        //public: '0.0.0.0:80',  //無效
        disableHostCheck: true,
    }
}

[轉]Kubernetes 调整 nodePort 端口范围

https://qhh.me/2019/08/pod 文件定义在 /etc/kubernetes/manifests/kube-apiserver.yaml15/Kubernetes-%E8%B0%83%E6%95%B4-nodePort-%E7%AB%AF%E5%8F%A3%E8%8C%83%E5%9B%B4/

在 command 下添加 --service-node-port-range=1-65535 参数,修改后会自动生效,无需其他操作:



apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    component: kube-apiserver
    tier: control-plane
  name: kube-apiserver
  namespace: kube-system
spec:
  containers:
  - command:
    - kube-apiserver
    - --service-node-port-range=1-65535
    - --advertise-address=192.168.26.10
    - --allow-privileged=true
    - --authorization-mode=Node,RBAC
    - --client-ca-file=/etc/kubernetes/pki/ca.crt
    - --enable-admission-plugins=NodeRestriction
    - --enable-bootstrap-token-auth=true
    - --etcd-cafile=/etc/kubernetes/pki/etcd/ca.crt
    - --etcd-certfile=/etc/kubernetes/pki/apiserver-etcd-client.crt
    - --etcd-keyfile=/etc/kubernetes/pki/apiserver-etcd-client.key
    - --etcd-servers=https://127.0.0.1:2379
    - --insecure-port=0
    - --kubelet-client-certificate=/etc/kubernetes/pki/apiserver-kubelet-client.crt
    - --kubelet-client-key=/etc/kubernetes/pki/apiserver-kubelet-client.key
    - --kubelet-preferred-address-types=InternalIP,ExternalIP,Hostname
    - --proxy-client-cert-file=/etc/kubernetes/pki/front-proxy-client.crt
    - --proxy-client-key-file=/etc/kubernetes/pki/front-proxy-client.key
    - --requestheader-allowed-names=front-proxy-client
    - --requestheader-client-ca-file=/etc/kubernetes/pki/front-proxy-ca.crt
    - --requestheader-extra-headers-prefix=X-Remote-Extra-
    - --requestheader-group-headers=X-Remote-Group
    - --requestheader-username-headers=X-Remote-User
    - --secure-port=6443
    - --service-account-key-file=/etc/kubernetes/pki/sa.pub
    - --service-cluster-ip-range=10.96.0.0/12
    - --tls-cert-file=/etc/kubernetes/pki/apiserver.crt
    - --tls-private-key-file=/etc/kubernetes/pki/apiserver.key
    image: registry.aliyuncs.com/google_containers/kube-apiserver:v1.15.2
    imagePullPolicy: IfNotPresent
    livenessProbe:
      failureThreshold: 8
      httpGet:
        host: 192.168.26.10
        path: /healthz
        port: 6443
        scheme: HTTPS
      initialDelaySeconds: 15
      timeoutSeconds: 15
    name: kube-apiserver
    resources:
      requests:
        cpu: 250m
    volumeMounts:
    - mountPath: /etc/ssl/certs
      name: ca-certs
      readOnly: true
    - mountPath: /etc/pki
      name: etc-pki
      readOnly: true
    - mountPath: /etc/kubernetes/pki
      name: k8s-certs
      readOnly: true
  hostNetwork: true
  priorityClassName: system-cluster-critical
  volumes:
  - hostPath:
      path: /etc/ssl/certs
      type: DirectoryOrCreate
    name: ca-certs
  - hostPath:
      path: /etc/pki
      type: DirectoryOrCreate
    name: etc-pki
  - hostPath:
      path: /etc/kubernetes/pki
      type: DirectoryOrCreate
    name: k8s-certs
status: {}

k8s kubernetes Lesson 8 Error

Error: User "system:serviceaccount:kube-system:default" cannot get resource "namespaces"


https://github.com/fnproject/fn-helm/issues/21#issuecomment-545317241


kubectl create serviceaccount --namespace kube-system tiller
kubectl create clusterrolebinding tiller-cluster-rule --clusterrole=cluster-admin --serviceaccount=kube-system:tiller
kubectl patch deploy --namespace kube-system tiller-deploy -p '{"spec":{"template":{"spec":{"serviceAccount":"tiller"}}}}'
helm init --upgrade --service-account tiller

docker registry Other Way


On root home

openssl req -nodes -newkey rsa:4096 -keyout certs/docker-registry.key -out certs/docker-registry.csr -subj "/C=/ST=/L=/O=/OU=/CN=docker-registry"
openssl x509 -req -sha256 -days 365 -in certs/docker-registry.csr -signkey certs/docker-registry.key -out certs/docker-registry.crt


docker run -dp 5000:5000 --name registry -v "$(pwd)"/certs:/certs \
-e REGISTRY_HTTP_TLS_CERTIFICATE=/certs/docker-registry.crt \
-e REGISTRY_HTTP_TLS_KEY=/certs/docker-registry.key \
registry


nano /etc/hosts 
> 192.168.99.118 docker-registry

cd /etc/docker
mkdir certs.d
cd certs.d
mkdir docker-registry:5000
cd docker-registry:5000
cp ~/certs/docker-registry.crt ca.crt

===== check registry is working
docker image pull busybox
docker image tag busybox docker-registry:5000/mybusybox
docker image push docker-registry:5000/mybusybox
docker run --rm docker-registry:5000/mybusybox echo "Hello from busybox"

//
docker rmi busybox docker-registry:5000/mybusybox
docker run --rm docker-registry:5000/mybusybox echo "Hello from busybox"

===== remove registry
docker container stop registry && docker container rm -v registry



https://jkzhao.github.io/2017/09/01/Registry%E7%A7%81%E6%9C%89%E4%BB%93%E5%BA%93%E6%90%AD%E5%BB%BA%E5%8F%8A%E8%AE%A4%E8%AF%81/

列出私有仓库中的所有镜像

curl -k -X GET https://docker-registry:5000/v2/_catalog  >> {"repositories":["mybusybox"]}

curl --cacert certs/docker-registry.crt https://docker-registry:5000/v2/_catalog

curl -k https://docker-registry:5000/v2/_catalog

Hyperledger Hurley is the development environment toolset

https://github.com/worldsibu/hurley#readme

[轉]covalent hyperledger code sample

https://docs.covalentx.com/article/73-code-samples

[轉]Hyperledger Composer is deprecated

https://hackernoon.com/hyperledger-composer-is-deprecated-kuzqu31cb

ethereum seth

https://github.com/dapphub/dapptools/tree/master/src/seth

Hyperledger KC Tam

https://medium.com/@kctheservant

http://www.ledgertech.biz/kcarticles.html


===========
https://hyperledger-fabric.readthedocs.io/en/release-1.4/tutorials.html

參考 [轉] Hyperledger Fabric 1.2系列 -- 将组织添加进通道: 手动执行

https://www.jianshu.com/p/09c67924da90

[轉]Hyperledger Fabric BYFN之配置進階篇

https://www.itread01.com/content/1550412200.html

1. byfn.sh up down會清理所有容器映象,生成的配置檔案和證書,現實場景應該可以停止或恢復區塊鏈網路,該如何處理?


byfn.sh down會呼叫networkdDown去銷燬整個網路和已生成的配置。byfn.sh restart則不會清理。

...........

注意

docker-compose down會停止和刪除容器,網路,映象和對映的卷。

只是停止服務的話的會最好使用docker-compose stop。

docker-compose up則是建立和啟動容器服務, 這裡用於啟動。

我們也可以參考例子fabric-samples/fabcar, 它會重用fabric-samples/basic-network中的start.sh, stop.sh允許停止和重啟。


2. byfn.sh還是fabcar兩個例子即使重啟區塊鏈網路,通道需要創新建立,節點需要重新加入通道,鏈碼也要全要重新安裝,如果節點多維護起來就麻煩且費時,重啟的時候能讓通道,節點,鏈碼,State DB自動恢復?



這自然是有的,但是必須開啟orderer, peer等的持久化配置。

...........


  orderer.example.com:
  ...
 - /mnt/hyperledger/orderer:/var/hyperledger/production/orderer


  peer0.org1.example.com:
  ...
  - /mnt/hyperledger/org1/peer0:/var/hyperledger/production


  couchdb:
  ...
  - /mnt/hyperledger/couchdb:/opt/couchdb/data




4. Peer節點我們配置了兩個埠,配置用來做什麼?



ports:

      - 7051:7051

      - 7053:7053

7051是Peer啟動的gRPC, 一般是客戶端應用接入。

7053是事件埠(Peer Event)

..........

Fabric 1.1之後peer event做了完全不同的設計,訊息的監聽不在peer節點了,而是基於channel,這樣設計提供了對Peer資料更細粒度的採訪控制和提供了接收訊息的可靠性。(官方文件是這麼扯,我也有點疑惑) 主要提供兩種服務,Deliver(通知提交到記賬本的整個區塊內容) 和DeliverFiltered(過濾一些區塊減少訊息通知返回的區塊大小)

Docker 本身DNS是不穩定的

再分享早上碰到docker穩定度問題,docker內到外網是靠本機的iptables做Nat出去,早上就發現運行很久的docker container,突然不送資料到ELK,一查發現DNS掛了,這之前也碰到幾次了,基本上不是中心DNS掛了,而且Docker本身架構的DNS掛了,基本上只要重啟docker service後就正常,無需對主機重啟,而重啟docker service是一件很嚴重的事情,因為上面所有的服務都會一併被下線,之後還要在把運行的服務全部重新上線…


也許我的理解是錯誤,但只能以目前的情況來判斷,也許是iptables nat轉換的問題,但本機沒有重開機,理論上就沒有這個問題才是。

[轉]What's New in Ethereum Serenity (2.0)

http://kimiwublog.blogspot.com/2018/12/whats-new-in-ethereum-serenity-20.html

需注意,時間是2018/12/06 內容肯不會是最正確的

[DIY] HyperLedger

1. Use docker-machine crate docker vm.

And install docker-compose.

2. https://github.com/hyperledger/fabric-samples



# Fetch bootstrap.sh from fabric repository using
curl -sS https://raw.githubusercontent.com/hyperledger/fabric/master/scripts/bootstrap.sh -o ./scripts/bootstrap.sh

# Change file mode to executable
chmod +x ./scripts/bootstrap.sh

# Download binaries and docker images
#./scripts/bootstrap.sh [version] [ca version] [thirdparty_version]

./scripts/bootstrap.sh

Here use all default value.


3. https://hyperledger-fabric.readthedocs.io/en/latest/build_network.html


# Start Run

cd fabric-samples/first-network  
./byfn.sh generate
./byfn.sh up

4. Hope you see

===================== Query successful on peer1.org2 on channel 'mychannel' =====================

========= All GOOD, BYFN execution completed ===========

5. check docker ps Need like this




PS:


1. See Error

2019-11-06 02:22:34.819 UTC [main] InitCmd -> ERRO 001 Cannot run peer because cannot init crypto, folder "/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/org1.example.com/users/Admin@org1.example.com/msp" does not exist
!!!!!!!!!!!!!!! Channel creation failed !!!!!!!!!!!!!!!!
========= ERROR !!! FAILED to execute End-2-End Scenario ===========

How to Fix


cd fabric-samples/first-network  
./byfn.sh down
./byfn.sh generate  #This maybe don't need
./byfn.sh up


6. How to querying chaincode again

https://learnblockchain.cn/2019/07/03/chaincode-run/


docker exec -it cli bash

root@73e65944cade:/opt/gopath/src/github.com/hyperledger/fabric/peer>


root@73e65944cade:/opt/gopath/src/github.com/hyperledger/fabric/peer>  peer chaincode query -C mychannel -n mycc -c '{"Args":["query","a"]}'

# peer chaincode query This command come from e2etest that you first time See This message:
========= All GOOD, BYFN execution completed =========== 
Then just find screen up, can see "peer chaincode query ooxxooxxooxx". Please copy it then use in here.


[轉]SSLH 是一款采用 C 语言编写的开源端口复用软件,目前支持 HTTP、SSL、SSH、OpenVPN、Tinc、XMPP 等多种协议识别

https://mp.weixin.qq.com/s/sHitMzs8KXXO6joX8QqO_A?fbclid=IwAR1UGD7gemvKRY-IkOCEHGDru6YLDkI2vXojKpLTc-AZ4gN2Zz849YwJKZ8


SSLH 是一款采用 C 语言编写的开源端口复用软件,目前支持 HTTP、SSL、SSH、OpenVPN、Tinc、XMPP 等多种协议识别。它主要运行于 *nix 环境,源代码托管在 GitHub 上。


项目地址:https://github.com/yrutschle/sslh

更简单地说,SSLH 允许我们在 Linux 系统上的同一端口上运行多个程序/服务。因此,您可以用同一端口来同时使用两种服务。如果你遇到大多数端口被防火墙阻止的情况,SSLH 就可以帮你派上大用场。下面我们就来看一个 SSL 和 SSH 同时复用同一端口的实例。

[轉][Flutter]还在大量使用TextEditingController?试试这种解决方案

当用户输入大量信息时,通常会采用TextField列表来解决,这时如果需要对每个TextField进行控制或监听就需要大量的TextEditingController。
这里提供另一种思路,解决大量使用TextEditingController和信息整理困难的问题。
定义一个Map:
Map _userInfo;
这个Map作用于所有需要收集用户信息的地方。
使用TextField时这样操作:


////邮箱
 TextField(
    controller: TextEditingController(text: _userInfo['account']),
    onChanged: (value) {
        _userInfo['account'] = value;
    },
),
////昵称
 TextField(
    controller: TextEditingController(text: _userInfo['nickname']),
    onChanged: (value) {
        _userInfo['nickname'] = value;
    },
),
////密码
 TextField(
    controller: TextEditingController(text: _userInfo['password']),
    onChanged: (value) {
        _userInfo['password'] = value;
    },
),


这里全程未单独定义TextEditingController,只使用TextField默认的方法进行控制,且可以获得以下好处:
1.节省大量代码,简化业务逻辑。
2.用户输入完成时即得到一个包含所有信息的Map。
3.输入的内容不会丢失,只要这个Map不被销毁,下次进入(或返回)这个页面时所有内容都在,不用要求用户再次输入,提升用户体验。
第一次发文章,如有问题,欢迎指正。


作者:xSILENCEx
链接:https://juejin.im/post/5d649bfce51d453b1d648314
来源:掘金
著作权归作者所有。商业转载请联系作者获得授权,非商业转载请注明出处。

dart null list

減少null判斷情況

https://stackoverflow.com/questions/51036758/flutter-the-method-map-was-called-on-null
https://juejin.im/post/5c6d38b1f265da2dcc7feb69
https://cloud.tencent.com/developer/article/1370380

?? => if null

https://blog.csdn.net/ffa_ijj/article/details/85051156


return qres?.map((value) {
  LinkedHashMap result = json.decode(value["jsonitem"]);
  return result;
})?.first ?? new LinkedHashMap();

這個判斷方式有個問題,當查詢回來為[],不是null情況下,在.first會出錯,因為 "No element"會出錯,但.toList()會正確,故改回


if (qres == null || qres.isEmpty) return new Member(); // 待確定是否出錯

var resmap = qres.first;
return new Member.fromJson(json.decode(resmap["jsonitem"]));

git 不同專案使用不同帳號

git global 已設定,但其他專案需要設定其他的帳號

到專案目錄下的.git內,修改config檔案,補上

[user]
name = ooxx
email = ooxx@gmail.com

即可蓋過global

dart json serialisation dson

https://github.com/drails-dart/dart-serialise
https://github.com/parnham/dart-serialise

https://github.com/dart-league/dson

json to dart flutter

https://javiercbk.github.io/json_to_dart/

https://ashamp.github.io/jsonToDartModel/

[轉]datatable datatables nodejs

https://newcodingera.com/datatables-server-side-processing-using-nodejs-mysql/

https://1drv.ms/u/s!At2KEcnT9DVaiw88MAEXeML0bRf3

Important! SqlInjection



======================
datatables mongodb
https://github.com/deepikagunda/datatables

[轉]secp256k1簽章的message,長度都必須是256 bits,也就是32 bytes

https://medium.com/@antonassocareer/web3-secp256k1-%E7%B0%BD%E7%AB%A0%E8%88%87solidity%E9%A9%97%E7%AB%A0-26ded518cfdc

那麼如果我們想要單純用私鑰簽章一段資料,不要有Ethereum定義的那些prefix的話,就必須要直接調用 secp256k1 這一包library了。不過在用之前要知道,所有要丟給secp256k1簽章的message,長度都必須是256 bits,也就是32 bytes。剛剛我們說web3的簽名函式丟什麼都可以,是因為它會幫我加上prefix之後再做sha3 Hash (keccak),最後一定會變成一個32 bytes的東西。如果我們自己純靠私要簽章訊息的話,也勢必要先通過這個函式來整理input長度

sha3 Hash (keccak)

bip39 mnemonic bip32 seed ed25519 elliptic



const bip39 = require('bip39')
const bip32 = require('bip32');
const EC = require('elliptic').ec;

json =`test json file`
mnemonic = "簡 熙 夢 幾 聲 可 高 汪 煙 版 統 仇"
path = "m/2018'/5'/1'/0/1"

const sJWSinit = async () => {
  console.log('-----sJWS Initial Start----- \n');

  dkey = await DeriveKey(mnemonic, path)
  console.log("\nGet dkey: %o \n", dkey)
  
  console.log('\n-----elliptic ed25519 Start----- \n');

  var EdDSA = require('elliptic').eddsa
  var ec = new EdDSA('ed25519');
  var eckeypair = ec.keyFromSecret(dkey.privateKey)
  
  var privateKeyHex = new Buffer.from(eckeypair.getSecret()).toString('hex')
  var publickeyHex = new Buffer.from(eckeypair.getPublic()).toString('hex')
  console.log("private key hex: %o", privateKeyHex)
  console.log("public key hex: %o\n", publickeyHex)

  var signature = eckeypair.sign(json).toHex();
  console.log("signature: %o\n", signature)

  var ec2 = new EdDSA('ed25519');
  var ec2keypair2 = ec2.keyFromPublic(publickeyHex, 'hex');
  console.log("EdDSA json verify: %o", ec2keypair2.verify(json, signature));
}

(async () => {
  console.log("--- aysnc sJWS init---")
  await sJWSinit();
})();

async function DeriveKey(mnemonic, derivePath) {
  if (bip39.validateMnemonic(mnemonic)) { console.log("mnemonic is fake!") }

  return bip39.mnemonicToSeed(mnemonic).then((vseed)=>{
    var root = bip32.fromSeed(vseed)
    var PathNode = root.derivePath(derivePath)
        
    console.log("# PATH 是 m/2018'/5'/1'/0/1/0  因為底下為derive(0),所以 path + '/0' \n")
    console.log("privateKey (Hex): %o", PathNode.derive(0).privateKey.toString('hex'))
    console.log("publicKey (Hex): %o", PathNode.derive(0).publicKey.toString('hex')) // 024ac10a81e3a0f86cb4dad68c6a26031d805a057f36048f80a5b91b1c2cb0588c 符合

    return {
      prv_buf: PathNode.derive(0).privateKey,
      pub_buf: PathNode.derive(0).publicKey,
      wif: PathNode.derive(0).toWIF(),
      publicKey: PathNode.derive(0).publicKey.toString('hex'),
      privateKey: PathNode.derive(0).privateKey.toString('hex'),
      path: derivePath
    }
  }).catch((e) => {
    console.error('handle error here: ', e.message)
  })
     
}

bitcoinjs-lib HDNode.fromSeedBuffer error bip39 bip32 Address bitcoin ethereum

bitcoinSecp256r1.HDNode.fromSeedBuffer 無法使用,目前正確應該是用 bitcoinSecp256r1.bip32.fromSeed

jsrsasign 有異常


const bip39 = require('bip39')
const bip32 = require('bip32');
const bitcoinSecp256r1 = require('bitcoinjs-lib')
const ethUtil = require('ethereumjs-util')
const EC = require('elliptic').ec;

// bitcoinSecp256r1.HDNode.fromSeedBuffer 無法使用,目前正確應該是用 bitcoinSecp256r1.bip32.fromSeed

mnemonic = "簡 熙 夢 幾 聲 可 高 汪 煙 版 統 仇"
path = "m/2018'/5'/1'/0/1"
type = "secp256r1"

// 驗證網頁 https://iancoleman.io/bip39/#chinese_traditional

if (bip39.validateMnemonic(mnemonic)) { console.log("mnemonic is fake!") }
const seed = bip39.mnemonicToSeed(mnemonic).then((vseed)=>{
  var root = bip32.fromSeed(vseed)
  var PathNode = root.derivePath(path)

  console.log("---------------------------------------------")
  console.log("# PATH 是 m/2018'/5'/1'/0/1/ \n")
  console.log("Bitcoin Address: %o 符合 \n", getAddress(PathNode)) // 1GcgQJN7XgqkZkQcD4dzaZ7bjCFvQ6wxF2 符合 m/2018'/5'/1'/0/1
  console.log("root toWIF: %o", root.toWIF())
  console.log("PathNode toWIF: %o 符合", PathNode.toWIF()) // Kzq7FAYiWjDAcwU44FvcyCsCpJyLCD19n13FyQgLY6oBNajYcAYz 符合 m/2018'/5'/1'/0/1
  console.log("--------------------------------------------- \n")

  // 底下為derive(0),所以正確是 m/2018'/5'/1'/0/1/0 為 path + '/0'
  console.log("---------------------------------------------")
  console.log("# PATH 是 m/2018'/5'/1'/0/1/0  因為底下為derive(0),所以 path + '/0' \n")
  console.log("privateKey (WIF): %o 符合", PathNode.derive(0).toWIF()) // L5ccMER4KyRn6pY6amvrFAHacpEsKrH1eTjDNeWwgXMnqjSCUU6N 符合
  console.log("privateKey (Buffer): %o", PathNode.derive(0).privateKey)
  console.log("privateKey (String): %o", PathNode.derive(0).privateKey.toString())
  console.log("privateKey (Hex): %o", PathNode.derive(0).privateKey.toString('hex'))
  console.log("privatekeyHex: %o \n", PathNode.derive(0).privkeyHex)
  console.log("publicKey (Hex): %o 符合", PathNode.derive(0).publicKey.toString('hex')) //024ac10a81e3a0f86cb4dad68c6a26031d805a057f36048f80a5b91b1c2cb0588c 符合
  console.log("Bitcoin Address: %o 符合", getAddress(PathNode.derive(0))) //1Gp8AuHiYyBixrvLkKtC4VDhxpvK8PmYEr 符合
  console.log("--------------------------------------------- \n")


  console.log('\n-----elliptic Initial Start----- \n');
  
  var ec = new EC('p256');
  let keyPair = ec.keyFromPrivate("83CFCC6EF1864C3303A5F8DEF2540167CB2DFA5DD22BB8D197B396972525FD56")
  let pubKey = keyPair.getPublic();
  console.log("pubKey: %o", pubKey)

  // https://github.com/kjur/jsrsasign/issues/394
  // sha512('aaa') => d6f644b19812e97b5d871658d6d3400ecd4787faeb9b8990c1e7608288664be77257104a58d033bcf1a0e0945ff06468ebe53e2dff36e248424c7273117dac09
  let msgHash = 'd6f644b19812e97b5d871658d6d3400ecd4787faeb9b8990c1e7608288664be7'

  let signatureBase64 = 'MEUCIBEcfv2o3UwqwV72CVuYi7HbjcoiuSQOULY5d+DuGt3UAiEAtoNrdNWvjfdz/vR6nPiD+RveKN5znBtYaIrRDp2K7Ks='
  let signatureHex = Buffer.from(signatureBase64, 'base64').toString('hex');
  let validSig = ec.verify(msgHash, signatureHex, pubKey);
  console.log("Signature valid? %o \n", validSig);

  // use json
  var ec = new EC('secp256k1');
  keyPair = ec.keyFromPrivate(dkey.publicKey)
  pubKey = keyPair.getPublic();
  console.log("pubKey: %o", pubKey)

  var signature = keyPair.sign(json);
  var derSign = signature.toDER();
  //console.log("signature: %o", signature)
  console.log("json verify: %o", keyPair.verify(json, derSign));


  console.log('\n-----elliptic ed25519 Start----- \n');

  var EdDSA = require('elliptic').eddsa
  var ec2 = new EdDSA('ed25519');
  var ec2keypair = ec2.keyFromSecret(dkey.privateKey)
  //console.log("key: %o", key)
  var signature = ec2keypair.sign(json).toHex();
  console.log("signature: %o", signature)

  var privateKeyHex = new Buffer(ec2keypair.getSecret()).toString('hex')
  var publickeyHex = new Buffer(ec2keypair.getPublic()).toString('hex')
  console.log("private key hex: %o", privateKeyHex)
  console.log("public key hex: %o", publickeyHex)

  var ec2keypair2 = ec2.keyFromPublic(publickeyHex, 'hex');
  console.log("EdDSA json verify: %o", ec2keypair2.verify(json, signature));


  bip39.mnemonicToSeed(mnemonic).then((vseed)=>{
    var root = bitcoinSecp256r1.bip32.fromSeed(vseed)
    var PathNode = root.derivePath(path)
    console.log("bitcoinSecp256r1 privateKey (Hex): %o", PathNode.derive(0).privateKey.toString('hex'))
    console.log("bitcoinSecp256r1 publicKey (Hex): %o", PathNode.derive(0).publicKey.toString('hex')) 
    
    const buf = Buffer.allocUnsafe(32);
    new Buffer.from(msgHash).copy(buf, 0, 0, 32)
    //msgbuf32 = new Buffer("01234567890123456789012345678901")
    console.log("msgHash buf 32: %o", buf.toString("hex"))
    var ecPair = bitcoinSecp256r1.ECPair.fromPrivateKey(PathNode.derive(0).privateKey)
    var signstring = ecPair.sign(buf)
    console.log("signstring: %o", signstring.toString("hex"))
    var verifyresult = ecPair.verify(buf, signstring)
    console.log("verify: %o", verifyresult)
  })
})

DeriveKey(mnemonic, path, type).then((v)=>{
  console.log("dkey: %o", v)
});

function getAddress (node, network) {
  return bitcoinSecp256r1.payments.p2pkh({ pubkey: node.publicKey, network }).address
}

function getEthereumAddress(privkeyHex) {
  const hexAddress = ethUtil.privateToAddress(Buffer.from(privkeyHex, 'hex')).toString('hex')
  const checksumAddress = ethUtil.toChecksumAddress(hexAddress)
  return checksumAddress
}

function DeriveKey(mnemonic, derivePath, type) {
  switch (type) {
    case "secp256r1":
      if (bip39.validateMnemonic(mnemonic)) { console.log("mnemonic is fake!") }

      return bip39.mnemonicToSeed(mnemonic).then((vseed)=>{
        var root = bip32.fromSeed(vseed)
        var PathNode = root.derivePath(derivePath)
          
        console.log("# PATH 是 m/2018'/5'/1'/0/1/0  因為底下為derive(0),所以 path + '/0' \n")
        console.log("privateKey (Hex): %o", PathNode.derive(0).privateKey.toString('hex'))
        console.log("publicKey (Hex): %o 符合", PathNode.derive(0).publicKey.toString('hex')) // 024ac10a81e3a0f86cb4dad68c6a26031d805a057f36048f80a5b91b1c2cb0588c 符合

        const buf = Buffer.allocUnsafe(32);
        PathNode.derive(0).privateKey.copy(buf, 0, 0, 32)
        console.log("Ethereum Address: %o 符合", getEthereumAddress(buf.toString('hex')) ) // 0xe020343a09086F53a203c9A0Ea76010049399575 符合
          
        return {
          pub_buf: PathNode.derive(0).publicKey,
          wif: PathNode.derive(0).toWIF(),
          publicKey: PathNode.derive(0).publicKey.toString('hex'),
          privateKey: PathNode.derive(0).privateKey.toString('hex'),
          ethAddress: getEthereumAddress(buf.toString('hex')),
          path: derivePath
        }
      }).catch((e) => {
        console.log('handle error here: ', e.message)
      })
        
      break;

    default:
      throw "type should be secp256k1 or secp256r1";
  }
}

smart contract storage struct 未初始化 直接使用問題

https://github.com/knownsec/Ethereum-Smart-Contracts-Security-CheckList/blob/master/%E4%BB%A5%E5%A4%AA%E5%9D%8A%E6%99%BA%E8%83%BD%E5%90%88%E7%BA%A6%E5%AE%A1%E8%AE%A1CheckList.md#11-%E6%9C%AA%E5%88%9D%E5%A7%8B%E5%8C%96%E7%9A%84%E5%82%A8%E5%AD%98%E6%8C%87%E9%92%88

https://www.chaindd.com/3102377.html

https://blog.b9lab.com/storage-pointers-in-solidity-7dcfaa536089

https://medium.com/loom-network/ethereum-solidity-memory-vs-storage-how-to-initialize-an-array-inside-a-struct-184baf6aa2eb

Use delete or new

web3 deploy smart contract 1.2.1

Use https://remix.ethereum.org Get Contract json and data.


In remix website, Compile finish. See Compliation Details.


1. ABI: click ABI buttion, get data. Use http://jsonviewer.stack.hu/ remove space

2. Compliation Details -> WEB3DEPLOY -> get data


3. cContract.options.from need put correct.


var Web3 = require("web3");
var provider = new Web3.providers.HttpProvider("http://ganache:8545");
var web3 = new Web3(provider);

//abi
var cContract = new web3.eth.Contract([{"constant":false,"inputs":[{"name":"x","type":"uint256"}],"name":"set","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"get","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}])

//bytecode
cContract.options.data = '0x608060405234801561001057600080fd5b5060bf8061001f6000396000f30060806040526004361060485763ffffffff7c010000000000000000000000000000000000000000000000000000000060003504166360fe47b18114604d5780636d4ce63c146064575b600080fd5b348015605857600080fd5b5060626004356088565b005b348015606f57600080fd5b506076608d565b60408051918252519081900360200190f35b600055565b600054905600a165627a7a72305820765480c908e5e28e3233e18bfa422944b42cad5fc08b77d7b22d3ddd7016a1380029'

cContract.options.from = '0xoooxxxoooxxxoooxxxoooxxxoooxxx'
cContract.options.gas = '4700000'

console.log("web3 version: %o", web3.version)
web3.eth.getAccounts().then(o=>{console.log(o)})

cContract.deploy().send()
.on('error', (error) => {
    console.log("error: %o", error)
})
.on('transactionHash', (transactionHash) => {
    console.log("transactionHash: %o", transactionHash)
})
.on('receipt', (receipt) => {
    // receipt will contain deployed contract address
    console.log("receipt: %o", receipt)
    console.log("receipt.contractAddress: %o", receipt.contractAddress) 
})
.on('confirmation', (confirmationNumber, receipt) => {
    console.log("confirmationNumber: %o", confirmationNumber)
    console.log("confirmation receipt: %o", receipt)
})
.then(function(newContractInstance){
    if (typeof newContractInstance.options.address !== 'undefined') {
        console.log('Contract mined! address: ' + newContractInstance.options.address);
    }else{
        console.log("newContractInstance.address is undefined!")
    }
});

HDWalletProvider web3 smart contract connection need to stop or pool

HDWalletProvider engine.stop()



p = HDWalletProvider(MNEMONIC_SYSTEM, "http://ganache:8545", 0);
p.engine.stop();


HDWalletProvider engine.stop() and pool



export function GetHdProvider(id: number, rpcurl: string) {
  //return new HDWalletProvider(MNEMONIC_SYSTEM, url, id);

  return id==0?Provider1Pool.acquire():Provider2Pool.acquire();
}

// Normal use
const hdProvider0 = await GetHdProvider(0, providerUrl).then(function(client) {return client}).catch(function(err) {throw new HttpException(err.toString(), HttpStatus.BAD_REQUEST);});

const hdProvider1 = await GetHdProvider(1, providerUrl).then(function(client) {return client}).catch(function(err) {throw new HttpException(err.toString(), HttpStatus.BAD_REQUEST);});

// Normal release
ReleaseHDProvider1(hdProvider1 );

// Pool code
const genericPool = require("generic-pool");

const opts = {
  max: 10, // maximum size of the pool
  min: 2, // minimum size of the pool
  idleTimeoutMillis: 30000,
  log: true
};

const factory0 = {  // maybe different parms
  create: function() {
    return new HDWalletProvider(MNEMONIC_SYSTEM, RPCURL, 0);
  },
  destroy: function(client) {
    client.engine.stop();
  }
};

const factory1 = {  // maybe different parms
  create: function() {
    return new HDWalletProvider(MNEMONIC_SYSTEM, RPCURL, 1);
  },
  destroy: function(client) {
    client.engine.stop();
  }
};

export function ReleaseHDProvider1(client){
  Provider1Pool.release(client);
  console.log("Provider1Pool status: pool.size %o pool.available %o pool.pending %o", Provider1Pool.size, Provider1Pool.available, Provider1Pool.pending)
}

export function ReleaseHDProvider2(client){
  Provider2Pool.release(client);
  console.log("Provider2Pool status: pool.size %o pool.available %o pool.pending %o", Provider2Pool.size, Provider2Pool.available, Provider2Pool.pending)
}

const Provider1Pool = genericPool.createPool(factory0, opts);
const Provider2Pool = genericPool.createPool(factory1, opts);

Project專案

‎Triton Ho‎ https://www.facebook.com/groups/616369245163622/permalink/1736421439825058/

今天不寫發大財的事,直接寫一下project planning的雜感好了。

——————————————————————————————————————————————————————

最兇險的專案不是那些deadline定得很趕的專案,而是那些沒有deadline的專案!

別以為「沒有deadline」是真的沒有deadline耶。

你想一下,跟你大大聲說「錢不是問題的人」,最終有120%是「反正我又沒錢,錢當然不是問題啊~」。

公司不是做慈善的,也不是給工程師來試新玩具的。所有的專案,最終還是要談C/P值。

(再次一句:工程就是來談C/P的,不談C/P請去當藝術家)

所謂「沒有deadline」,這很可能代表……

A) 你的主管現在忙別的專案管理,暫時沒空管這專案。

(然後等他有空回來看這專案時,就會問為何拖這麼久還結不了案了)

B) 你沒法拒絕其他人的需求改動。(背景聲:反正沒deadline,改一下需求去做得更好吧)

C) 你沒法有效限制專案的複雜性,大量的over-engineering。(背景聲:反正沒deadline,寫得好一點/多留一點空間,這樣子未來才容易維護嘛)

A+B+C的後果是……老闆過了三個月,突然有空來看看大家做什麼時,發現這專案已經過了二個月還沒有做完。

然後要求:都做了三個月了,現在再給你二星期時間來結案耶!

結果是:

要麼結不了案,投入大量心力的專案成為上不了市場的垃圾。

要麼是勉強能結案,但是有大量的over-engineering和一堆因為需求改了又改下不好的程式加構。

——————————————————————————————————————————————————————

雖然一堆入市未深的工程師整天會罵專案deadline為何定得那麼硬,一天都不能改……

但是嘛,先不談專案,我們談一下去旅行好了。

去旅行嘛,第一件事當然是跟公司申請休假,然後把信用卡丟給另一半叫她幫忙規劃(註:這是高度危險動作,好孩子絕對別學)。

http://xn--axxxx-fg1h292av9ap80aa49or2n76lzmxyz1bcr7i.com/,sxxxxxxxxx.com,txxxxxxxxxx.com上天天比價比優惠看旅行遊記的生活~

然後如果沒定下死線?應該我進棺材那一天還是在計劃行程中~

(謎之聲:某人站在你身後,她看起來很火……)

計劃行程的死線能不能改?當然不行,公司休假可是改不動啊!!!

回到公司專案,為何公司死線定得那麼硬,很多時候都是跟業務宣傳/合約罰款有關的。

你想像一下,一個手游專案要上市,當然不是先等程式完成後才慢慢宣傳衝人氣的。

一個遊戲要上市,當然是先定好上市日期,然後預先數月就要慢慢地製造話題,找人來做宣傳,一步一步炒熱氣氛。

然後人氣炒到最高點,玩家的期待度到達最大時,遊戲同步開賣大賺特賺那一波。

如果突然發現有bug,遊戲要延期一個月?

sorry囉,遊戲消費是不理性的,過了那一波熱潮,本來會付錢的玩家們早就付給另一個遊戲了。

讓話題多炒熱一個月去等bug先修好?

你以為是炒青菜,你想炒多久就多久嗎?

先不談熱度能否額外維持一個月還不消散。但是,高人流的宣傳管道,網上KOL,不是你想付錢就能立即買到的!

如果你沒法如期把遊戲上市,那麼你這個遊戲很可能就賠本賠很很大囉。

——————————————————————————————————————————————————————

專案deadline不能改,商業社會就是這樣子了。

追求要完美的,你應該去當藝術家不是當工程師的。

怎去在deadline前做完專案,固然跟你是否有留下足夠的buffering有關。

但是,這跟你的專案怎計劃也有很大關係的。

上古時期,有一堆人(CMMI)覺得,只要把文件寫得好,每一個專案把工序所用的時間都記錄下來。

然後你就能越來越變得成熟,能很精準地預估下一個專案所需時間了~

然後這些CMMI人大約會覺得:把台北的象山步道走100次,就能很精準地預估爬玉山攻項要多少時間了(笑~)

(香港版本:走城門水塘100次,就能預估蚺蛇尖攻項要多少時間了)

會行山的人都知道:

地圖/網上文章只能給你一個很基本的大概,一個路線最終要用多少時間/體力,你只能親自走一次才能答出來。

然後嘛……

很多表面上看起來相同的軟體專案,真正做下去時才發現是全新的未知領域……

——————————————————————————————————————————————————————

如果專案deadline不能改,那麼能改的就是:軟件的質素了。

以去旅行為例:

如果你有非常充份的時間,你買機票時大可以找不同銀行的信用卡優惠,看看飛行里數計劃,看看連同旅行一起訂的優惠……

如果沒時間,http://xn--skyxxxxxxx-rl5q.com/,輸入出發和回程時間,那一家最便宜就按下去算了。

一個能賣錢的軟體專案,正常應該可以再拆分為多個sub-task和milestone的。

重點:

首先開始做的,應該是最困難/你最沒法預估開發難度的工作。

A) 

專案越早階段要改動上市日期,你能成功改動宣傳計劃的可能性就越高。

B) 

越早發現專案進度不理想。之後比較容易的sub-task,你還是能以減少testcase coverage,刪掉不重要功能這些手段去追回進度。

如果你把困難而且必要的工作放在最後才做,那麼任何的預估錯誤就是專案延期囉~

(註1:一堆人覺得堅持一定要先寫testcase才能寫程式的……要麼他真的很幸福沒遇上過要衝死線的專案,要麼他活在童話世界……)

(註2:deadline前做不完的軟體功能嘛……如果不是關鍵性的,看看能不能當成bug再後補囉~)

——————————————————————————————————————————————————————

專案到底先做什麼:

我們以(重要/不重要),和(容易/困難)來給每一個sub-task排一下:

如果你明知deadline是完全不合理,你怎也沒可能把全部重要功能都做完,那麼就先做(重要+容易),在死線前能多做一個功能就多一個功能。

否則,先做(重要+困難)的。因為(重要+容易)的工作,常常是總有一點時間可以偷下來的。越近deadline,你越會珍惜你每一秒不做多餘的事。

重要工作全做完後,然後是(不重要+容易),在deadline前能做多少就多少。

(不重要+困難)工作嘛,讓他留在backlog算了。

——————————————————————————————————————————————————————

後記:

在只發了一篇文下,RDBMS課程普通票全賣光了

(謎之聲:你不是說五分鐘會搶光嗎?)

歡迎來買石虎愛心票耶XD

https://datasci.kktix.cc/events/rdbms20191005

另外,高流量雜感的淺談,定在10/10和10/11的早上9:30—12:00(二天內容相同)

請繼續耐心等候正式報名頁面……

HEX 0x string to []byte to string DecodeString

https://play.golang.org/p/i90_qsN2Sz-


package main

import (
 "fmt"
 "encoding/hex"
)

func main() {
 id := "0x1dd84569ad60faa1b6838526ba7156388cf7c8d376ed0ccda9bce0419c2c3519"
 fmt.Printf("Ori ID: %v \n\n", id)
 fmt.Printf("Ori ID[2:]: %v \n\n", id[2:])
 
 byteid := []byte(id)
 fmt.Printf("===== Byte id ===== Decimal \n")
 fmt.Printf("Byte ID: %v \n", byteid)
 fmt.Printf("Byte ID 0x%x \n\n", byteid)
 
 fmt.Printf("===== Decode(Byte id[2:]) ===== Decimal HEX \n")
 byteid = []byte(id[2:])
 fmt.Printf("Byte ID: %v \n", byteid)
 fmt.Printf("Byte ID 0x%x \n\n", byteid)
 n, _ := hex.Decode(byteid, byteid)
 fmt.Printf("Byte ID[2:]: %v \n", byteid)
 fmt.Printf("Byte ID[2:] 0x%x \n", byteid)
 fmt.Printf("Byte ID[2:] [:n]: %v \n", byteid[:n])
 fmt.Printf("Byte ID[2:] [:n] 0x%x \n\n", byteid[:n])

 fmt.Printf("===== id ===== Decimal \n")
 idbyte32 := covertStringTByte32(id)
 fmt.Printf("Byte32 ID: %v \n", idbyte32 )
 //fmt.Printf("String ID: %s \n", idbyte32 )
 fmt.Printf("HEX ID: 0x%x \n\n", idbyte32 )
 
 fmt.Printf("===== id[2:] ===== Decimal \n")
 idbyte32 = covertStringT2Byte32(id)
 fmt.Printf("Byte32 ID: %v \n", idbyte32 )
 //fmt.Printf("String ID: %s \n", idbyte32 )
 fmt.Printf("HEX ID: 0x%x \n\n", idbyte32 )
 
 fmt.Printf("===== DecodeString(id[2:]) ===== HEX \n")
 idbyte32 = covertStringDecodeStringByte32(id)
 fmt.Printf("Byte32 ID: %v \n", idbyte32 )
 //fmt.Printf("String ID: %s \n", idbyte32 )
 fmt.Printf("HEX ID: 0x%x \n", idbyte32 )
}

func covertStringTByte32(t string) [32]byte {
 var b32 [32]byte
 copy(b32[:], t)
 return b32
}

func covertStringT2Byte32(t string) [32]byte {
 var b32 [32]byte
 copy(b32[:], t[2:]) //remove 0x
 return b32
}

func covertStringDecodeStringByte32(t string) [32]byte {
 data, err := hex.DecodeString(t[2:])
 if err != nil {
  fmt.Printf("ERR \n")
 }
 
 fmt.Printf("DecodeString data: %v \n", data)
 fmt.Printf("DecodeString data length: %v \n\n", len(data))
 
 var b32 [32]byte
 copy(b32[:], data)
 return b32
}


Ori ID: 0x1dd84569ad60faa1b6838526ba7156388cf7c8d376ed0ccda9bce0419c2c3519 

Ori ID[2:]: 1dd84569ad60faa1b6838526ba7156388cf7c8d376ed0ccda9bce0419c2c3519 

===== Byte id ===== Decimal 
Byte ID: [48 120 49 100 100 56 52 53 54 57 97 100 54 48 102 97 97 49 98 54 56 51 56 53 50 54 98 97 55 49 53 54 51 56 56 99 102 55 99 56 100 51 55 54 101 100 48 99 99 100 97 57 98 99 101 48 52 49 57 99 50 99 51 53 49 57] 
Byte ID 0x307831646438343536396164363066616131623638333835323662613731353633383863663763386433373665643063636461396263653034313963326333353139 

===== Decode(Byte id[2:]) ===== Decimal HEX 
Byte ID: [49 100 100 56 52 53 54 57 97 100 54 48 102 97 97 49 98 54 56 51 56 53 50 54 98 97 55 49 53 54 51 56 56 99 102 55 99 56 100 51 55 54 101 100 48 99 99 100 97 57 98 99 101 48 52 49 57 99 50 99 51 53 49 57] 
Byte ID 0x31646438343536396164363066616131623638333835323662613731353633383863663763386433373665643063636461396263653034313963326333353139 

Byte ID[2:]: [29 216 69 105 173 96 250 161 182 131 133 38 186 113 86 56 140 247 200 211 118 237 12 205 169 188 224 65 156 44 53 25 56 99 102 55 99 56 100 51 55 54 101 100 48 99 99 100 97 57 98 99 101 48 52 49 57 99 50 99 51 53 49 57] 
Byte ID[2:] 0x1dd84569ad60faa1b6838526ba7156388cf7c8d376ed0ccda9bce0419c2c35193863663763386433373665643063636461396263653034313963326333353139 
Byte ID[2:] [:n]: [29 216 69 105 173 96 250 161 182 131 133 38 186 113 86 56 140 247 200 211 118 237 12 205 169 188 224 65 156 44 53 25] 
Byte ID[2:] [:n] 0x1dd84569ad60faa1b6838526ba7156388cf7c8d376ed0ccda9bce0419c2c3519 

===== id ===== Decimal 
Byte32 ID: [48 120 49 100 100 56 52 53 54 57 97 100 54 48 102 97 97 49 98 54 56 51 56 53 50 54 98 97 55 49 53 54] 
HEX ID: 0x3078316464383435363961643630666161316236383338353236626137313536 

===== id[2:] ===== Decimal 
Byte32 ID: [49 100 100 56 52 53 54 57 97 100 54 48 102 97 97 49 98 54 56 51 56 53 50 54 98 97 55 49 53 54 51 56] 
HEX ID: 0x3164643834353639616436306661613162363833383532366261373135363338 

===== DecodeString(id[2:]) ===== HEX 
DecodeString data: [29 216 69 105 173 96 250 161 182 131 133 38 186 113 86 56 140 247 200 211 118 237 12 205 169 188 224 65 156 44 53 25] 
DecodeString data length: 32 

Byte32 ID: [29 216 69 105 173 96 250 161 182 131 133 38 186 113 86 56 140 247 200 211 118 237 12 205 169 188 224 65 156 44 53 25] 
HEX ID: 0x1dd84569ad60faa1b6838526ba7156388cf7c8d376ed0ccda9bce0419c2c3519 

Program exited.


https://onlineutf8tools.com/convert-hexadecimal-to-utf8