Diploma and thoughts on dapps

As you may know, I've been intensively writing my diploma for the last couple of weeks. Of course, right before the deadline. Actually, the last week was a huge mess.

The point was to develop software that enables paid subscriptions for Telegram channels. Moreover, the solution had to be as decentralized as possible. To put it simply, there shouldn't be one point of failure, and users should be able to transfer tokens back and forth without the involvement of a third party. Another requirement was a usage of some stablecoin instead of highly volatile token.

With this in mind I've digged into blockchain technology. The final solution consists of four components:

1. Smart-contract (solidity/brownie/python/pytest) that acts as a database and stores all the logic. Source code is right here.

2. Telegram bot (python/python-telegram-bot/web3.py) that acts as an admin in provided channels adding/removing subscribers. It also helps to verify a user and added channels. Moreover, bot can retrieve an information from smart-contract.

3. Frontend (dart/flutter/flutter_web3) that integrates with Metamask and aims to interact with smart-contract. It has to be here, so users can sign transactions with their private keys and pay a small commission for every transaction that changes state.

4. Script (python, web3.py, cron) that triggers the payment process for debtors (runs daily).

Here are some of the insights and conclusions I came to during the research and development process:

- Transactions that aim to change the state of smart-contract are not free. These transactions require gas. Gas is like a fuel that allows Ethereum network to operate. Gas price measures in ETH. At the time I was testing the interaction with the smart-contract, each transaction cost me about 0.3$. Happily, I was testing it on Rinkeby testnet, where you can get some ETH for free.

- Many apps that claim that they are dapps are at best only half dapps. Fully decentralized solutions shouldn't depend on centralized servers or databases. My solution can't be fully decentralized as Telegram is a centralized software. On top of that, I can't give a bot token to everyone, so they can do whatever they want.

- If some dapp asks you to approve spending of a large number of tokens, claiming it'll improve user experience, don't go along with it. Even if contract is open sourced. If there is a hole in smart-contract, all approved tokens could disappear forever.

- It follows from the previous point that the contract must be covered by tests up and down.

- Solidity isn't really cool. I had to store an array of user addresses for a mapping that maps user address to user structure only to be able to iterate through users. I've also couldn't find any utility methods for arrays/strings/mappings. How to live without generics?!

- One authoritive HR said that large companies, during the recruitment process, look through developer's CV and make a note when they see cryptoprojects in the experience section. It may show that money is more important for a developer than solving complex problems.

#crypto #blockchain #dev #thoughts