FIN4Xplorer consists of two parts:
- Smart contracts that are deployed to the Ethereum blockchain. The entire functionality is in these smart contracts. Everything could also be done by interacting with them via a command line.
- A frontend or client in the form of a Web DApp that acts as an user interface for convenient interaction with said smart contracts. Web apps run directly in the browser, both on desktop computers and on smartphones. DApp stands for distributed app, meaning they connect to a blockchain.
Infrastructure, programming languages and frameworks used¶
We decided to use the Ethereum blockchain for now. It satisfies our requirements of an open-source and public blockchain that supports smart contracts. Furthermore it is used widely these days and therefore plenty support resources are available.
Rinkeby is one of a few Ethereum test networks and behaves similar to the main network. The difference is, that Ether, the „currency“ used to pay for transactions, is not worth „real“ money. On the main network Ether has to be earned via mining or bought on trading plattforms. On Rinkeby it can be requested from „faucets“ for free, see section Getting Ether.
During development we use Ganache from truffle locally to simulate an Ethereum blockchain.
The frontend is a React app that uses drizzle from truffle to connect to the smart contracts on the Ethereum blockchain. For now we don’t have native mobile apps. Mobile users have to use DApp browser apps and navigate to the same site as desktop users. The layout of the fronted works well on different screen sizes as relatively narrow boxes are arranged per page. Depending on the width of the browser window, they will either be rendered next to each other or below one another.
The only, yet significant, difference a visitor of a Web DApp experiences compared to a Web App, is the need for a „bridge to the blockchain“. Also called a digital wallet. Its first task is to establish the connection to the blockchain network - either via a full node that users run themselves or via a gateway service like Infura. Its second task is to pop up whenever the user seeks to write data to the blockchain and enable the convenient signing of such transactions with the users private key.
There are many organizations and projects out there offering digital wallets in different stages of maturity and compatibility. While the trend goes towards deeper and native integration into browser (or even operation systems), for now the market appears scattered.
The digital wallet we are using ourselves, and that seems to be the currently best supported one out there, is MetaMask: metamask.io. MetaMask is available both as extension for desktop browsers (Chrome, Firefox, Opera and Brave) and as early-stage mobile app (iOS and Android).
Once you have a digital wallet, either restore an existing account or follow the process to create a new account. In most digital wallets, creating a new account involves the randomized mathematical creation of a new and unique mnemonic (also called „seed phrase“). From this, one or more accounts, each with a public address and a matching private key, can be derived deterministically. Meaning you only have to remember/store (the digital wallet will probably remind you thoroughly to do so) the mnemonic to restore your account(s) anytime on any machine. Usually only the first account per mnemonic will be used.
After having created your new account, don’t forget to switch to the Rinkeby Test Network. By default you will be on the Main Ethereum Network.
After installing a digital wallet and creating an account, the last step before being ready to use FIN4Xplorer is to get some Rinkeby Ether (ETH). All transactions on the Ethereum (test) network cost Ether, the so called gas fee. The price depends on the current workload of the network as well as how many additions/changes to data on smart contracts your transaction causes. On test networks, Ether can be obtained for free from „faucets“. On the main network, Ether has either to be earned by being an active participant in the network (running a full node and doing mining), has to be traded or has to be bought on exchanges.
For obtaining Ether on the Rinkeby test network we suggest two options:
- Using the „authenticated faucet“ at faucet.rinkeby.io requires a social media post
- We build our own little faucet server that gives a small amount of ETH per click if the user has less then a threshold value: click Request Ether on the landing page of demo.finfour.net and wait a little until you get a confirmation message.