Demo

hadoop@hadoop-Inspiron-5547:~$ pwd

/home/hadoop

hadoop@hadoop-Inspiron-5547:~$ mkdir helloworld

hadoop@hadoop-Inspiron-5547:~$ cd helloworld/

hadoop@hadoop-Inspiron-5547:~/helloworld$ pwd

/home/hadoop/helloworld

hadoop@hadoop-Inspiron-5547:~/helloworld$ truffle unbox webpack

Downloading...

Unpacking...

Setting up...

Unbox successful. Sweet!

Commands:

Compile: truffle compile

Migrate: truffle migrate

Test contracts: truffle test

Run linter: npm run lint

Run dev server: npm run dev

Build for production: npm run build

hadoop@hadoop-Inspiron-5547:~/helloworld$ code .

This opens visual code editor.

add HelloWorld.sol under contracts.

pragma solidity ^0.4.17;

contract HelloWorld {

function sayHello\(\) returns \(string\){

    return \(" Hello  World"\);

}

}

then update 2_deploy_contracts.js to add hello world sol file.

var ConvertLib = artifacts.require("./ConvertLib.sol");

var MetaCoin = artifacts.require("./MetaCoin.sol");

var HelloWorld = artifacts.require("./HelloWorld.sol");

module.exports = function(deployer) {

deployer.deploy(ConvertLib);

deployer.link(ConvertLib, MetaCoin);

deployer.deploy(MetaCoin);

deployer.deploy(HelloWorld);

};

hadoop@hadoop-Inspiron-5547:~/helloworld$ truffle compile

Compiling ./contracts/ConvertLib.sol...

Compiling ./contracts/HelloWorld.sol...

Compiling ./contracts/MetaCoin.sol...

Compiling ./contracts/Migrations.sol...

/home/hadoop/helloworld/contracts/HelloWorld.sol:4:5: Warning: No visibility specified. Defaulting to "public".

function sayHello\(\) returns \(string\){

^

Spanning multiple lines.

,/home/hadoop/helloworld/contracts/HelloWorld.sol:4:5: Warning: Function state mutability can be restricted to pure

function sayHello\(\) returns \(string\){

^

Spanning multiple lines.

Writing artifacts to ./build/contracts

The above step will create build directory with the helloworld contrac.t ( equivalent json file ) in it.

open another tab and testrpc command ... this opens ethereum testrpc session..

update truffle.js to include the following lines.

// Allows us to use ES6 in our migrations and tests.

require('babel-register')

module.exports = {

networks: {

development: {

  host: 'localhost',

  port: 8545,

  network\_id: '\*', // Match any network id

  gas: 4600000

}

}

}

hadoop@hadoop-Inspiron-5547:~/helloworld$ truffle migrate

Using network 'development'.

Running migration: 1_initial_migration.js

Deploying Migrations...

... 0x8b8eb0f6bb9d5873eed54a073e2e4b1065b8afe8efe10d07dcfb111e55f81140

Migrations: 0xd9d83c686f37df233df3e7e5350b71449e5f7cc0

Saving successful migration to network...

... 0xf14161b0d54e6f91713620a2d779211b30a2632cb2b6c1e8b80c71a45ab39cc2

Saving artifacts...

Running migration: 2_deploy_contracts.js

Deploying ConvertLib...

... 0xfcc74b199d59a3d232d1ecc175db91e576dabdc785e776e4f5b8f5c64179d5ac

ConvertLib: 0x7389e4373db3e761295f43ea2b8bb9193ce0ed5b

Linking ConvertLib to MetaCoin

Deploying MetaCoin...

... 0x80a9591826a7be5b8ff94bbbcab9b06d2894954d52b0fff7ccd5188076cdcdd3

MetaCoin: 0x3c67d7bac9ea8b6174e476ecd237d4f027559823

Deploying HelloWorld...

... 0xc612875a1b900735eafee3016f4ab65742f8784576110781801de688d82e9575

HelloWorld: 0xdb343f0ba44ecd6501fce23764fb705a91a776ae

Saving successful migration to network...

... 0xc2dc16834323335fde708b56162e5ccf35c4d696cbcf1228af1d2d3002d0a530

Saving artifacts...

In testrpc console ( which was opened before) you will see something like

( transaction might be contract creation or state updates)

Transaction: 0x8b8eb0f6bb9d5873eed54a073e2e4b1065b8afe8efe10d07dcfb111e55f81140

Contract created: 0xd9d83c686f37df233df3e7e5350b71449e5f7cc0

Gas usage: 269607

Block Number: 1

Block Time: Wed Nov 22 2017 09:28:56 GMT+0530 (IST)

eth_newBlockFilter

eth_getFilterChanges

eth_getTransactionReceipt

eth_getCode

eth_uninstallFilter

eth_sendTransaction

Transaction: 0xf14161b0d54e6f91713620a2d779211b30a2632cb2b6c1e8b80c71a45ab39cc2

Gas usage: 41981

Block Number: 2

Block Time: Wed Nov 22 2017 09:28:56 GMT+0530 (IST)

eth_getTransactionReceipt

eth_accounts

net_version

net_version

eth_sendTransaction

Transaction: 0xfcc74b199d59a3d232d1ecc175db91e576dabdc785e776e4f5b8f5c64179d5ac

Contract created: 0x7389e4373db3e761295f43ea2b8bb9193ce0ed5b

Gas usage: 99726

Block Number: 3

Block Time: Wed Nov 22 2017 09:28:56 GMT+0530 (IST)

eth_newBlockFilter

eth_getFilterChanges

eth_getTransactionReceipt

eth_getCode

eth_uninstallFilter

eth_sendTransaction

Transaction: 0x80a9591826a7be5b8ff94bbbcab9b06d2894954d52b0fff7ccd5188076cdcdd3

Contract created: 0x3c67d7bac9ea8b6174e476ecd237d4f027559823

Gas usage: 332608

Block Number: 4

Block Time: Wed Nov 22 2017 09:28:56 GMT+0530 (IST)

eth_newBlockFilter

eth_getFilterChanges

eth_getTransactionReceipt

eth_getCode

eth_uninstallFilter

net_version

net_version

eth_sendTransaction

Transaction: 0xc612875a1b900735eafee3016f4ab65742f8784576110781801de688d82e9575

Contract created: 0xdb343f0ba44ecd6501fce23764fb705a91a776ae

Gas usage: 142596

Block Number: 5

Block Time: Wed Nov 22 2017 09:28:56 GMT+0530 (IST)

eth_newBlockFilter

eth_getFilterChanges

eth_getTransactionReceipt

eth_getCode

eth_uninstallFilter

eth_sendTransaction

Transaction: 0xc2dc16834323335fde708b56162e5ccf35c4d696cbcf1228af1d2d3002d0a530

Gas usage: 26981

Block Number: 6

Block Time: Wed Nov 22 2017 09:28:56 GMT+0530 (IST)

eth_getTransactionReceipt

hadoopf@hadoop-Inspiron-5547:~/helloworld$ truffle console ( if this is opened anotherwindow , make sure this is invoked from the corresponding truffle project )

truffle(development)> HelloWorld

it will the information about HelloWorld contract including ABI

create the instance of HelloWorld contract to invoke the methods

truffle(development)> HelloWorld.deployed().then(function(instance) {hello = instance; })ell

as helllo is instance to asyn calls , we should invoke a method called call() to retrieve the contents

truffle(development)> hello.sayHello.call()

' Hello World'

truffle(development)> .exit