Ethereum is an open source platform for creating and deploying distributed applications.

Ethereum is backed up by a large number of computers (also known as nodes)—all interconnected and storing data in a distributed ledger. Distributed ledger here means that a copy of this ledger is available to each and every node on the network. It provides flexibility to its developers to deploy their solution to multiple types. Developers should choose an appropriate network based on their requirements and use cases. These different networks also help in deploying solutions and smart contracts on networks that do not actually cost any Ether or money. There are networks that are free of cost while there are ones that require its users to pay in terms of Ether or other currencies for its usage.

Implementation of Ethereum nodes and clients is available in multiple languages, including Go, C++, Python, JavaScript, Java, Ruby, and more. The functionality or usability of these clients are the same across languages, and developers should choose an implementation they are most comfortable with. This book uses the Go implementation known as Geth, which acts as an Ethereum client to connect to public and test networks. It is also used to create the mining and EVM (transaction nodes) for private networks. Geth is a command-line tool written in Go for creating a node and miners on a private chain. It can be installed on Windows, Linux, and Mac as well. Now, its time to install Geth.

The first...

After Geth is installed, it can be configured to run locally without connecting to any network on the internet. Every chain and network has a genesis block or the first block. This block does not have any parent and is the first block of the chain. A genesis.json file is required to create this first block. A sample genesis.json file is shown in the following code snippet:

{  
"config": {
"chainId": 15,
"homesteadBlock": 0,
"eip155Block": 0,
"eip158Block": 0
},
"nonce": "0x0000000000000042",
"mixhash": "0x0000000000000000000000000000000000000000000000000000000000000000",
"difficulty": "0x200",
"alloc": {},
"coinbase": "0x0000000000000000000000000000000000000000",
"timestamp": "0x00",
"parentHash&quot...

There are following two distinct phases in the overall modification and writing of transactions to a ledger using Ethereum:

• The first stage is about creating a transaction and putting the transaction in a transaction pool.
• The second phase that happens periodically is to get all transactions from a transaction pool and mine them. Mining here means writing those transactions to the Ethereum database or ledger.

From this description, it would be a time-consuming process if the same process is used for development and testing purposes. To ease the process of development and test of solutions and smart contracts on Ethereum, ganache-cli was created. It was earlier known as TestRPC. ganache-cli by itself contains both the Ethereum transaction processing and mining functionality. Moreover, there is no waiting period for mining of transactions. The transactions are...

Solidity is one of the languages that is used to author smart contracts. Smart contracts will be dealt with in detail in the following chapters. The code written using Solidity is compiled using a Solidity compiler, which outputs byte code and other artifacts needed for deployment of smart contracts. Earlier, Solidity was part of the Geth installation; however, it has moved out of Geth and should be deployed using its own installation.

The Solidity compiler also known as solc can be installed using npm:

npm install -g solc

The preceding command line generates the following output:

The web3 library is an open source JavaScript library that can be used to connect to Ethereum nodes from the same or a remote computer. It allows IPC as well as RPC to connect to Ethereum nodes. web3 is a client-side library and can be used alongside a web page and query and can submit transactions to Ethereum nodes. It can be installed using the node package manager as a node module like the Solidity compiler. At the time of writing, the latest version of web3 is broken and does not install appropriately because of the missing BigNumber.js file. However, previous stable versions can be used for connecting web applications to backend Ethereum nodes. Let's take a look at the following steps to install the web3 JavaScript library:

1. The command used to install web3 is as follows:

npm install web3@0.19

The preceding command generates the following...

Ethereum works with Ether cryptocurrency and a wallet is required to send and receive Ether. Mist is an implementation of the same. Mist is a wallet used to send and receive Ether. It helps in executing transactions on the Ethereum network. The network can be public or private. It allows users to create their accounts, send and receive Ether, and deploy and invoke contracts.

Mist can be downloaded from https://github.com/ethereum/mist/releases. Download an appropriate ZIP file (in this case it is Ethereum-Wallet-win64-0-9-2.zip since we are deploying on Windows 2016) and extract to a file location. Double-click on the Ethereum Wallet application from the extracted files as shown in the following screenshot:

This should start Mist. Mist is an intelligent wallet. If a private chain is running on a local machine then it can identify the same and connect to it. If there...