HolaMundo con ethereum
Lista de herramientas
- testRPC
- nvm
- web3
- geth
- solc
- web3
Instalación
Linux
Los siguientes pasos muestras como instalar las herramientas necesarias en Ubuntu 17.04
curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.2/install.sh | bash nvm ls-remote nvm install <la ultima LTS> npm install -g ethereumjs-testrpc npm install solc npm install web3
Mac
Para instalar nvm es necesario tener brew
brew install nvm nvm ls-remote nvm install <la ultima LTS> npm install -g ethereumjs-testrpc npm install solc npm install web3
Desarrollo
Con el editor preferido, escribir el contrato, para esto se va a utilizar el lenguage solidity, sin embargo existen otras opciones como serpent.
Para compilar el contrato vamos a utilizar el comando solc --bin --optimize <archivo.sol>
Escribit el siguiente contrato en un archivo llamado Voting.sol
pragma solidity ^0.4.11;
// We have to specify what version of compiler this code will compile with
contract Voting {
/* mapping field below is equivalent to an associative array or hash.
The key of the mapping is candidate name stored as type bytes32 and value is
an unsigned integer to store the vote count
*/
mapping (bytes32 => uint8) public votesReceived;
/* Solidity doesn't let you pass in an array of strings in the constructor (yet).
We will use an array of bytes32 instead to store the list of candidates
*/
bytes32[] public candidateList;
/* This is the constructor which will be called once when you
deploy the contract to the blockchain. When we deploy the contract,
we will pass an array of candidates who will be contesting in the election
*/
function Voting(bytes32[] candidateNames) {
candidateList = candidateNames;
}
// This function returns the total votes a candidate has received so far
function totalVotesFor(bytes32 candidate) returns (uint8) {
if (validCandidate(candidate) == false) throw;
return votesReceived[candidate];
}
// This function increments the vote count for the specified candidate. This
// is equivalent to casting a vote
function voteForCandidate(bytes32 candidate) {
if (validCandidate(candidate) == false) throw;
votesReceived[candidate] += 1;
}
function validCandidate(bytes32 candidate) returns (bool) {
for(uint i = 0; i < candidateList.length; i++) {
if (candidateList[i] == candidate) {
return true;
}
}
return false;
}
}
Pasos para desplegar el contrato
Ejecutar node
Mientras se ejecutan los comandos, se puede ver su salida y analizarla.
Web3 = require('web3') web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
Listar las cuentas existentes en la red
web3.eth.accounts
Compilar el código
code = fs.readFileSync('Voting.sol').toString() solc = require('solc') compiledCode = solc.compile(code)
abiDefinition = JSON.parse(compiledCode.contracts[':Voting'].interface) VotingContract = web3.eth.contract(abiDefinition) byteCode = compiledCode.contracts[':Voting'].bytecode deployedContract = VotingContract.new(['Rama','Nick','Jose'],{data: byteCode, from: web3.eth.accounts[0], gas: 4700000}) deployedContract.address contractInstance = VotingContract.at(deployedContract.address)
> contractInstance.totalVotesFor.call('Rama') { [String: '0'] s: 1, e: 0, c: [ 0 ] } > contractInstance.voteForCandidate('Rama', {from: web3.eth.accounts[0]}) '0xdedc7ae544c3dde74ab5a0b07422c5a51b5240603d31074f5b75c0ebc786bf53' > contractInstance.voteForCandidate('Rama', {from: web3.eth.accounts[0]}) '0x02c054d238038d68b65d55770fabfca592a5cf6590229ab91bbe7cd72da46de9' > contractInstance.voteForCandidate('Rama', {from: web3.eth.accounts[0]}) '0x3da069a09577514f2baaa11bc3015a16edf26aad28dffbcd126bde2e71f2b76f' > contractInstance.totalVotesFor.call('Rama').toLocaleString() '3'
Opcodes de la EVM
0s: Stop and Arithmetic Operations
0x00 STOP Halts execution 0x01 ADD Addition operation 0x02 MUL Multiplication operation 0x03 SUB Subtraction operation 0x04 DIV Integer division operation 0x05 SDIV Signed integer 0x06 MOD Modulo 0x07 SMOD Signed modulo 0x08 ADDMOD Modulo 0x09 MULMOD Modulo 0x0a EXP Exponential operation 0x0b SIGNEXTEND Extend length of two's complement signed integer
10s: Comparison & Bitwise Logic Operations
0x10 LT Lesser-than comparison 0x11 GT Greater-than comparison 0x12 SLT Signed less-than comparison 0x13 SGT Signed greater-than comparison 0x14 EQ Equality comparison 0x15 ISZERO Simple not operator 0x16 AND Bitwise AND operation 0x17 OR Bitwise OR operation 0x18 XOR Bitwise XOR operation 0x19 NOT Bitwise NOT operation 0x1a BYTE Retrieve single byte from word
20s: SHA3
0x20 SHA3 Compute Keccak-256 hash
30s: Environmental Information
0x30 ADDRESS Get address of currently executing account 0x31 BALANCE Get balance of the given account 0x32 ORIGIN Get execution origination address 0x33 CALLER Get caller address. This is the address of the account that is directly responsible for this execution 0x34 CALLVALUE Get deposited value by the instruction/transaction responsible for this execution 0x35 CALLDATALOAD Get input data of current environment 0x36 CALLDATASIZE Get size of input data in current environment 0x37 CALLDATACOPY Copy input data in current environment to memory This pertains to the input data passed with the message call instruction or transaction 0x38 CODESIZE Get size of code running in current environment 0x39 CODECOPY Copy code running in current environment to memory 0x3a GASPRICE Get price of gas in current environment 0x3b EXTCODESIZE Get size of an account's code 0x3c EXTCODECOPY Copy an account's code to memory
40s: Block Information
0x40 BLOCKHASH Get the hash of one of the 256 most recent complete blocks 0x41 COINBASE Get the block's beneficiary address 0x42 TIMESTAMP Get the block's timestamp 0x43 NUMBER Get the block's number 0x44 DIFFICULTY Get the block's difficulty 0x45 GASLIMIT Get the block's gas limit
50s Stack, Memory, Storage and Flow Operations
0x50 POP Remove item from stack 0x51 MLOAD Load word from memory 0x52 MSTORE Save word to memory 0x53 MSTORE8 Save byte to memory 0x54 SLOAD Load word from storage 0x55 SSTORE Save word to storage 0x56 JUMP Alter the program counter 0x57 JUMPI Conditionally alter the program counter 0x58 PC Get the value of the program counter prior to the increment 0x59 MSIZE Get the size of active memory in bytes 0x5a GAS Get the amount of available gas, including the corresponding reduction 0x5b JUMPDEST Mark a valid destination for jumps
60s & 70s: Push Operations
0x60 PUSH1 Place 1 byte item on stack 0x61 PUSH2 Place 2-byte item on stack … 0x7f PUSH32 Place 32-byte (full word) item on stack
80s: Duplication Operations
0x80 DUP1 Duplicate 1st stack item 0x81 DUP2 Duplicate 2nd stack item … 0x8f DUP16 Duplicate 16th stack item
90s: Exchange Operations
0x90 SWAP1 Exchange 1st and 2nd stack items 0x91 SWAP2 Exchange 1st and 3rd stack items … … 0x9f SWAP16 Exchange 1st and 17th stack items
a0s: Logging Operations
0xa0 LOG0 Append log record with no topics 0xa1 LOG1 Append log record with one topic … … 0xa4 LOG4 Append log record with four topics
f0s: System operations
0xf0 CREATE Create a new account with associated code 0xf1 CALL Message-call into an account 0xf2 CALLCODE Message-call into this account with alternative account's code 0xf3 RETURN Halt execution returning output data 0xf4 DELEGATECALL Message-call into this account with an alternative account's code, but persisting the current values for `sender` and `value`
Halt Execution, Mark for deletion
0xff SELFDESTRUCT Halt execution and register account for later deletion
Referencias
- https://github.com/creationix/nvm
- https://github.com/ethereumjs/testrpc
- https://en.wikipedia.org/wiki/Remote_procedure_call
- http://ethdocs.org/en/latest/network/test-networks.html
- https://medium.com/@doart3/ethereum-dapps-without-truffle-compile-deploy-use-it-e6daeefcf919
- https://medium.com/@mvmurthy/full-stack-hello-world-voting-ethereum-dapp-tutorial-part-1-40d2d0d807c2
- https://github.com/ethereum/yellowpaper
Notas
testrpc -n5