There are many ways to get started with smart contract development. Exemplary you will learn how to get the login smart contract used in the Ethereum_user_connector module running in testrpc and how use browser solidity.
There are plenty of other Solidity integrations available.
Solidity
Is the programming language to write Smart Contracts. Solidity is a high-level language whose syntax is similar to that of Javascript. It reminds to TypeScript, because it is statically typed to target the Ethereum Virtual Machine.
http://solidity.readthedocs.io/en/latest/
Testing Blockchains
Ganache is a local Ethereum client including a block explorer. Easy way to start testing your Blockchain development with your own local test blockchain. https://github.com/trufflesuite/ganache Ganache is based on ganache-cli.
ganache-cli former "testrpc" is a Node.js based Ethereum client for testing and development. It uses ethereumjs to simulate full client behavior and make developing Ethereum applications much faster. https://github.com/trufflesuite/ganache-cli https://github.com/trufflesuite/ganache-cli#looking-for-testrpc
Truffle
Truffle is a popular open source development framework for Ethereum. It allows you to develop contracts, write tests and deploy them on different Ethereum networks.
http://truffleframework.com/ https://github.com/consensys/truffle
Browser solidity
Browser Solidity browser based development- and runtime environment for Solidity smart contracts.
http://ethereum.github.io/browser-solidity
Transaction signer
Ethereum is based on a public/private key system. In order to verify transactions you will need a Transaction signer. Currently this is tested with Metamask browser plug-in for Chromium based browsers. Metamask injects a web3js object into the browser which enables signing transactions on any Ethereum network.
The GNU licensed Mist browser developed by the Ethereum Foundation should work as well.
Drupal Ethereum Module intends to implement more TX signers in future releases.
Infura
Infura provides Ethereum as a service. In the background Metamask uses Infura infrastructure and we can use it to connect to Ethereum test- or main network.
Drupal community has been given a special access token for easy getting started. For use beyond testing, please register your own free access token at infura.io.
When using installing testrpc your Ethereum network node is reset every time you start.
You will need node.js and npm and git running.
###Install
Install Truffle and Testrpc and get the Register Drupal smart contract.
# Install testrpc
npm install -g ethereumjs-testrpc
# Install truffle
npm install -g truffle
# Clone Login Smart contract
git clone https://github.com/digitaldonkey/register_drupal_ethereum.git
###testrpc
The challenge is to connect a Ethereum Account with the local testrpc environment and make sure you have some Test-Ether available in the account.
####Option 1
If you start restrpc without any parameters it will create a number off accounts which own some test-Ether.
You may use truffle console to transfer Ether to the the account in Metamask:
# Start testrpc
testrpc
In an new terminal window:
You need to Connect Metamask to a private network localhost:8545, which in our case is provided by testrpc.
Send one Ether to the address 0xaEC98826319EF42aAB9530A23306d5a9b113E23D. The address you copy from your Metamask wallet.
# Start truffle console
truffle console
# Replace t
web3.eth.sendTransaction({from: web3.eth.accounts[0], to: "0xaEC98826319EF42aAB9530A23306d5a9b113E23D", value: web3.toWei(5, "ether")});
Now your Account in Metamask should have a balance of 5 Ether.
####Option 2
Start testrpc with a defined account using it's private key is a more easily repeatable.
First export the private key from Metamask wallet by clicking on the key.
Start testapc and add 10 Ether to the given account (10 Ether = 10000000000000000000 Wei)
testrpc --account="0x<YOUR PRIVATE KEY>,10000000000000000000"
Now your Account in Metamask should have a balance of 10 Ether.
###Deploy the contract
Truffle connects to localhost:8545 by default. If you have testrpc running it will connect there.
Alternatively you may run Geth or other Ethereum clients locally or whatever client locally to connect to Ethereum test- or main networks. The process of migration with truffle is the same.
# Change into the login smart contract directory
cd register_drupal_ethereum
# run migration scipt
truffle migrate
Running migration: 1_initial_migration.js
Replacing Migrations...
Migrations: 0x6dc525e5f10feac8aad2e2cb54bb1bc87d224c9e
Saving successful migration to network...
Saving artifacts...
Running migration: 2_deploy_contracts.js
Replacing RegisterDrupal...
RegisterDrupal: 0xaaaafb8dbb9f5c9d82f085e770f4ed65f3b3107c
Saving successful migration to network...
Saving artifacts...
Contract is migrate to the address mentioned in RegisterDrupal (in this example: 0xaaaafb8dbb9f5c9d82f085e770f4ed65f3b3107c)
You will need to ensure drupal is set to localhost:8545 in /admin/config/ethereum/network. And that the migrated address is set in /admin/config/ethereum/user-connector.
Note:
The ABI of a smart contract is defined by type and name of a contract function call. If you change it, you will need to change these values in drupal_user_connector settings too. The other way: if you modify the login contract only a little, for example let the user pay some Ether for sign-up, you can keep the rest of the user signup module as it is.
####Developing with Truffle
# Change into the login smart contract directory
cd register_drupal_ethereum
# run migration scipt
truffle migrate
# run truffle's test server
truffle serve
Running migration: 1_initial_migration.js
Replacing Migrations...
Migrations: 0x6dc525e5f10feac8aad2e2cb54bb1bc87d224c9e
Saving successful migration to network...
Saving artifacts...
Running migration: 2_deploy_contracts.js
Replacing RegisterDrupal...
RegisterDrupal: 0xaaaafb8dbb9f5c9d82f085e770f4ed65f3b3107c
Saving successful migration to network...
Saving artifacts...
##Under the surface Drupal Backend uses ethereum-php which implements implementing the JSON-RPC API.
Drupal Frontend depends on web3js implementing Ethereum JavaScript-API.
##Future reading
More detailed getting started readings are A 101 Noob Intro to Programming Smart Contracts or the Hitchhiker’s Guide to Smart Contracts.