A moving story about a city siege and the difficulties of communication in modern distributed systems — A historical digression Once known as Byzantium at the time of classical antiquity, Constantinople has been subjected to many sieges (so many that their list has its own page on Wikipedia!). The generals surrounding the city had the problem of deciding to whether attack or not. To reach a consensus about whether to…

In this short article, we investigate three different approaches to how SSI concepts map on the blockchain infrastructure. — This is the first of a series of articles about SSI, Self-Sovereign Identity In this short article, we shortly compare three different approaches to implement a system of Self-Sovereign Identity (SSI) based on public-ledger/blockchain. We intend to classify the approaches by considering how much of the information is stored on…

A mysterious algorithm from Atari 2600 to Commodore 64 — Thanks to a random Twitter list I have found an interesting paper and I have become aware of the existence of a field of research called Archeogaming which uses the approaches and the methodology coming from archeology, historiography, and software engineering to dissect and analyze the design and the implementation…

Here we will shortly discuss how the msg.sender mechanism works. As usual we will experiment with small chunks of Solidity that you will be able to run in your browser At the core of the blockchain is the mechanism of adding blocks of transactions to the chain of blocks: this…

Reality is complex: please note that in the previous sentence complex has a very specific meaning; let’s just investigate a little more about it. Complexity Complexity theory has been inspired by some famous problems that come to the attention of the scientific community in the final decades of ‘800. One famous…

A look at the SafeMath library from OpenZeppelin — In Solidity, there are plenty of different alternatives to things you take for granted in other languages. Strings and math are two examples. “Arithmetic operations in Solidity wrap on overflow. This can easily result in bugs, because programmers usually assume that an overflow raises an error, which is the standard…

Getting started with Solidity — Strings of characters represent the very heart of every programming language because, you know, computers often interact with humans. For this reason, handling strings is one of the first functionalities developed in any language. Furthermore, the first test traditionally prints the string “Hello, world!” Solidity is not an exception. It…

How ‘selfdestruct’ works in Solidity and how it affects the life of the freshly self-destructed smart contract — For the purpose of this article, I have read some good sources, starting with “Why Do Smart Contracts Self-Destruct? Investigating the Selfdestruct Function on Ethereum,” a recent publication that really digs into self-destruct mechanisms. The selfdestruct command stands out in the general immutability of the blockchain: selfdestruct renders inoperable a…

In this short tutorial I will try to summarize few simple steps to configure Logstash to emit data to Azure Event Hubs Before starting just few words to describe the two components we will work on: Logstash — it’s a data processing pipeline that ingests, as rapidly as it can…