Umberto Domenico Ciccia’s Blog

Preparing for technical interviews can be a daunting experience, heavily demanding both logical problem-solving and deep language proficiency. However, choosing the right programming language can give you a significant advantage, and Python is frequently the language of choice for algorithmic interviews. Its clean, readable syntax mirrors pseudocode, allowing you to spend less time writing boilerplate and more time actively solving the problem. Furthermore, it comes armed with an extensive standard library and powerful built-in data structures that let you deploy complex algorithms with just a few lines of code. ...

Introduction Databases are at the heart of virtually every software system — from web applications to financial platforms to machine learning pipelines. But how do they actually work? What happens when you run a SELECT query? How are rows stored on disk? How do multiple transactions run concurrently without corrupting data? This post is a comprehensive guide to database theory, covering the full lifecycle of database design and operation: from conceptual modeling to physical storage, from SQL queries to concurrency control. Whether you are studying for an exam, preparing for a systems design interview, or simply curious about what happens beneath the ORM layer, this guide has you covered. ...

Introduction Computer networks are the backbone of modern computing. Every time you browse a website, send an email, or stream a video, you rely on a complex stack of protocols, algorithms, and hardware working together. This post is a comprehensive guide to how computer networks work — from the physical transmission of bits to the application-layer protocols you use daily. We will walk through the layered network models (OSI and TCP/IP), dive into each layer’s responsibilities, explore routing and addressing, examine transport-layer reliability, and cover essential application-layer protocols. We will also touch on security, cloud computing, peer-to-peer systems, and distributed architectures like blockchain. ...

Basic Application Architecture Developer Perspective A typical application is composed of: Build & Deploy Layer — CI/CD pipeline Server Layer — handles incoming requests Storage Layer — persists application data (can be external) Logging Storage Server — logs all events Metric Storage Server — logs all metrics Alert Server — alerts when something goes down Stateless vs Stateful Services Stateless: the server holds no session data between requests. Any instance can serve any request. Enables effortless horizontal scaling. Stateful: the server holds session data (e.g. WebSocket connections, in-memory cart). Requires sticky sessions (session affinity at the load balancer) or externalizing state to Redis/a DB. Stateless Stateful Horizontal scaling Trivial — add instances freely Hard — requires sticky sessions or external state Fault tolerance High — any replica serves the request Low — losing a server loses its session data Examples REST APIs, static servers WebSocket servers, game servers, video call nodes User Perspective Users simply make requests to the server and receive responses. ...

Ruby is a dynamic, interpreted, object-oriented language designed by Yukihiro “Matz” Matsumoto in the mid-1990s. Its design philosophy prioritizes developer happiness and productivity — Matz famously said Ruby is “optimized for developer joy.” Under the hood, Ruby is a surprisingly sophisticated language with a rich object model, a multi-phase interpreter pipeline, and powerful metaprogramming capabilities that let you reshape the language itself at runtime. These notes cover Ruby from the ground up: the syntax fundamentals, how the interpreter turns your source code into executable instructions, how memory is managed, and the metaprogramming system that makes Ruby one of the most flexible languages in existence. ...