Coding Smart Contracts – Tutorial Part II

How to use a smart contract from a java application

Photo of Natallia Martchouk, co-founder of trimplement
Natallia Martchouk, co-founder of trimplement, explains how to develop Ethereum smart contracts.

In Part I of my tutorial I’ve explained how to develop and deploy a simple smart contract. Today we will see how this deployed contract can be used in java applications. 

We are going to use Parity as Ethereum client and Web3j java library for interaction with Parity. I’m assuming that you already have installed Web3j, solc and Parity following “Prepare” instructions in Part I.

5. Get Parity Synced

First of all your Parity needs to get synchronized with the Ethereum testnet Rinkeby, meaning it needs to download the current database status to your local machine. Start your local parity with 

$parity --chain rinkeby --rpcapi "eth,net,web3,personal"

See also this documentation of Parity about getting synced.

In the meantime, we can prepare everything that we need to call our smart contract from a java application.

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Coding Smart Contracts – Tutorial Part I

How to Write, Deploy and Test a Smart Contract

Natallia Martchouk, co-founder of trimplement, the fintech enabler
Natallia Martchouk, co-founder of trimplement, explains how to develop Ethereum smart contracts.

In this article, I will give you a smart contract tutorial. It will tell you how to quickly write, test and deploy Ethereum smart contracts. My motivation is to help people to make the first steps. There are several good tutorials which helped me to get started. But I missed kind of a “cookbook recipe” for the entire journey, starting with the installation of tools and frameworks and ending with deployment to Ethereum and usage out of an application.

And so, I decided to write down all the steps involved and hope that you will find it helpful!

I’m working on a Mac, but I’ll provide links to the documentation of all tools and frameworks so that you’ll be able to find fitting instructions for your personal environment.

Today we will: 

  • Setup an environment that  allows you to write production-ready smart contracts
  • Write a simple smart contract
  • Test security and style guide issues with solhint
  • Write unit tests with a Truffle framework
  • Deploy the contract on the Rinkeby testnet using MetaMask and Remix
  • Execute calls on the deployed smart contract
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CoreExchange Feature Checklist

As a vendor of licensable fintech software products, we are often asked about our competitors and our USPs. Our customers want to know, what makes our products comparable and where we make a difference and have a special edge. In this article, I would like to elaborate on the feature set of our white label cryptocurrency trading platform CoreExchange and compare it to a couple of other well-known and popular exchanges.

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The Mona Lisa by Leonardo DaVinci, photographed and a Tourist photographing it with his smartphone, symbolizing digital transformation of art (i.e. with blockchain).

6 Art Projects Powered by Blockchain

At a first glance blockchain and art are polar opposites. But how do they say:  Opposites attract. Blockchain technology can help to solve many issues of the modern art market, for example:

  • It can help to securely and transparently track provenance, copyright and ownership information
  • It can provide frameworks for tokenization of real-world art objects, simplifying access to the art market and allowing “ordinary mortals” to become art investors and get partial ownership on expensive assets (see e.g. Maecenas project description below)
  • Blockchain and cryptography can be the art environment itself, meaning they can be used to create and store digital art objects (like Crypto-Kitties described below)
  • And of course, it can help artists to collect fundings for their art projects using the mechanisms of the so-called ICO (initial coin offering)

Let’s have a look at the most popular and interesting blockchain and art projects where creativity meets technology.

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