Ethereum Client

This project is a fork of https://www.npmjs.com/package/easy-ethereum-client

It likely works together with the Ethereum Service.

Modules

This project contents different modules.

Action Module

This module allows to create actions and their associated transactions.

New action

let actionClient = await new Action("action-buy-car", userId, [{collectionName: "cars", collectionObjectId: "5c9b60a39d3e152f1891b921"}]);

New Transaction

    var result = actionClient.transaction(
                    "setString",
                    [web3.utils.fromAscii("name"), "stringName"],
                    contractStorage.simple.address,
                    userAddress,
                    userPrivateKey,
                    transactionValue
            );

Contract Module

This module allows to create and store into the mongo database the contracts you need on your project and for each one their own abi.

let saveContract = await ContractModule.saveContractAbi(contractStorage.simple.address, JSON.stringify(contractStorage.simple.abi), "SimpleContract");

Once you stored your contracts in the database, you can retrieve the contract information with their name, when you create a transaction.

 actionClient.transaction(
        "setSimpleInt",
        [15],
        contractName,
        userAddress.toLowerCase(),
        userPrivateKey,
        transactionValue
 );

Event Module

This module allows to capture or emit new events with the EventEmitter. Also, this model captures 3 predefined events:

• on('hash'): When we get the hash for a transaction that we send to the blockchain.

• on('error'): When the transaction fails. Also, this event emits another one, that can be treated externally with the action name:

  transactionEvents.emit(actionObject.name + ".on-error", actionObject);

• on('validated'): When the transaction achieve the number of confirmations you set in the configuration file. Also, this event emits "actionName.on-completed" event if necessary. This only happens when all the transactions for a specific action have been finished successfully:

  transactionEvents.emit(actionObject.name + ".on-completed", actionObject);

Error Module

This Module allows to create a new Error, with a custom message and code.

    const {ErrorWeb3} = require('../Modules/ErrorModule');

Use:

    if(!trx){
            throw new ErrorWeb3("Transaction doesn't exist in the blockchain", ErrorWeb3.TRANSACTION_NOT_EXIST);
     }

Ethereum Client Usage

Example of usage of the Ethereum Client:

const {EthereumClient, Action, ContractModule} = require('ethereum-client-js');

const contractAddress = "0x";
const contractAbi = {};
const config = {
  project: "my-project",
  database: 'mongodb://localhost:27017/mydb',
  network: {
    name: "localhost",
    host: "http://127.0.0.1:8545",
  },

  rabbitQM: {
    connection: {
      name: 'default',
      host: 'localhost',
      user: 'guest',
      pass: 'guest'
    }
  },
  // Number of actions to process at the same time
  actionThreads: 10,
};

const EthereumClientPromise = async () => {
  EthereumClient.config(config.rabbitQM, config.network, config.project, config.database, config.actionThreads);
  console.log('Ethereum Client Configured');
  
  // Start Ethereum Client
  await EthereumClient.start();
  console.log('Ethereum Client Running');

  // Save contract abi
  try {
    await ContractModule.saveContractAbi(contractAddress, JSON.stringify(contractAbi), "my-contract");
    console.log('Smart Contract Read');
  } catch (e) {
    console.error('Error reading Smart Contract');
    process.exit();
  }
};

async function onCompleted(actionParam) {
  console.log("Completed");
  const event = await actionParam.getEvent("MyEvent");
  console.log(event);
}

async function onError(actionParam) {
  console.log("Error " + actionParam.name);
}

EthereumClientPromise().then(async () => {
    EthereumClient.on('my-action.on-completed', onCompleted);
    EthereumClient.on('my-action.on-error', onError);
    
    // Contract Call
    const senderAddress = "0x";
    const senderPk = "";
    const callParameters = [];
    const result = await EthereumClient.call("my-function", callParameters, contractAddress, senderAddress);
    console.log(result);
  
    // Send transaction
    const action = new Action("my-action");
    const transactionParameters = [];
    const transaction = action.transaction(
            "my-action",
            transactionParameters,
            contractAddress, senderAddress, senderPk, ""
    );
    await action.send();
})