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Simple Smart Contract

This tutorial shows step by step how to use Remix and Metamask, which are tools that were originally built for Ethereum, to create and deploy a simple smart contract on Velas EVM.

Get coins for testing - Airdrop instruction

Smart contract sample:

pragma solidity >=0.4.22 <0.7.0;


contract HelloWorld {
  function sayHello() external pure returns (string memory) {
   return 'Hello World';
 }
}

Compile contract​

  1. Go to Remix
  2. In the home page choose environment "Solidity" ans create new file "Hello_World.sol"
  3. Insert contract code and compile

Connect Metamask to public bridge-rpc​

To connect your metamask account to Velas public bridge-rpc:

  1. Open Metamask and go to networks
  2. Custom RPC
Network Name:
Velas Testnet

New RPC URL:
https://explorer.testnet.velas.com/rpc

ChainID (optional):
111

Connect Metamask to local node​

To get info about running your node check "Bridge to EVM" section. By default bridge runs on port 8545.

To connect your metamask account to local bridge:

  1. Open Metamask and go to networks

  2. Custom RPC

    Network Name:
    Velas Testnet

    New RPC URL:
    https://localhost:8545

    ChainID (optional):
    111

By default, node runs on 8545 port. Can be changed if node uses different port for bridge.

Deploy​

  1. Open Remix
  2. On the left side panel choose "Deploy and run transactions" section
  3. Choose environment "Injected Web3" to connect metamask account
  4. Choose "Hello_World.sol" contract in dropdown menu
  5. Press deploy button
  6. Confirm on Metamask popup window

Test​

Remix will add your contract instance on the same page for deploying. To test your code simply call "sayHello" method by pressing button in you new contract menu.