Representational State Transfer, often referred to as REST, is an architectural style used to design web services. It uses a stateless communication model between clients and servers, relies on standard HTTP methods, and focuses on simple but powerful conventions...
gRPC is a high-performance open-source framework that was developed at Google for remote procedure calls. It uses the Protocol Buffers (protobuf) serialization format by default and runs over HTTP/2 to support features like full-duplex streaming and efficient compression. Many microservices architec...
Data transmission in API design describes how information moves between a client and a server. It includes the request format, response format, protocol, headers, authentication details, compression behavior, caching rules, and error-handling signals. Good transmission design helps APIs remain fast...
GraphQL is a query language for APIs that allows clients to request exactly the data they need in a single request. It provides a type system to describe data and offers a more efficient, flexible, and powerful alternative to traditional REST-based architectures. These notes explore the fundamentals...
Network communications in a backend context involve the flow of data between clients and server-side systems. A client might be a browser, a mobile app, another backend service, an API gateway, or a scheduled job. The server might be a REST API, GraphQL API, gRPC service, WebSocket server, database...
A forward proxy sits between clients and the wider internet. Instead of connecting directly to an external service, the client sends the request to the proxy, and the proxy makes the outbound connection on the client’s behalf. This pattern is commonly used for egress control, caching, auditing, and ...
Apache Tomcat, often referred to as Tomcat, is an open-source web server and servlet container that implements the Java Servlet, JavaServer Pages (JSP), and WebSocket specifications. Maintained by the Apache Software Foundation, Tomcat serves as a robust and lightweight platform for hosting Java-bas...
Indexing is one of the most effective ways to optimize database queries. By maintaining auxiliary data structures that map certain key values to their physical or logical locations, indexes allow a database to rapidly locate rows that match a search condition. This reduces the number of full-table s...
Isolation levels in relational-database systems govern how simultaneously running transactions perceive one another’s changes. They sit on a spectrum that trades consistency guarantees—how “correct” every read is—against concurrency—how many transactions can safely overlap. Choosing the right level ...
Database transactions are a cornerstone of reliable data management. They let an application bundle multiple low-level reads and writes into a single, all-or-nothing unit so the database moves cleanly from one consistent state to another—even when dozens of users race to change the same rows or hard...
API communication protocols describe how different software components exchange data and invoke functionality across networks. They define the transport mechanisms, data formats, interaction styles, and often how developers should structure their requests and responses. These protocols are often cho...
Some git commands are powerful but risky because they can rewrite history, move branch tips, or discard work. Used carelessly, they break open reviews, hide teammates’ changes, and make it hard to trace what actually shipped. Treat history edits as exceptional: prefer additive fixes for shared code...
Tags mark exact commits. They’re perfect for releases, rollbacks, changelogs, and CI/CD triggers. Unlike branches, tags don’t move—ever—so you can always point to the exact build you shipped...
Git is a powerful tool, but its complexity often puzzles newcomers. Let’s break down some typical areas where users get tripped up in simpler terms...
HEAD is Git’s pointer to the snapshot you’re currently working on—the bookmark of your checkout. Most of the time, HEAD points to the tip of a branch (like master or main). When you commit, HEAD (and that branch) advance to the new commit...
Git branches are lightweight names that point to commits. Think of them as parallel timelines: you can try ideas on a branch without touching main, then merge back when you’re happy...
When managing software projects, organizations often need to choose between two distinct codebase structuring strategies: monorepos and multirepos. This decision isn’t just about where code lives—it affects collaboration, tooling, versioning, and even deployment practices. When you’re starting out o...
In Git, you might accumulate multiple small commits over the course of developing a new feature, fixing small bugs, or refactoring code. While these incremental commits are crucial during active development, they can clutter the project history in the long term. This clutter becomes especially evide...
Netlify allows you to easily deploy and manage static websites. A Python-based static site generator like Pelican, MkDocs, or Frozen-Flask produces HTML files that Netlify serves through its global CDN...
Digital Ocean provides cloud-based virtual machines called Droplets that let you deploy and manage CentOS servers. The overall flow looks like this...
Message queues enable asynchronous, decoupled communication in distributed systems by allowing publishers to send messages to a queue that consumers process independently, typically in first-in, first-out order. This approach reduces direct dependencies between services, enhances reliability and sca...
Operational Transform is a foundational technique in distributed systems that enables real-time collaborative editing of shared documents. Originally proposed by Ellis and Gibbs in 1989, OT allows multiple users to concurrently modify the same document while preserving consistency across all partici...
Linearizability is a consistency model that makes a distributed system appear as if there is only a single copy of the data, and every operation takes effect atomically at some point between its invocation and its response. Even when data is replicated across multiple nodes, a linearizable system gu...
Concurrent writes happen when two or more clients write to the same key in a database at the same time, each unaware of the other's write. In replicated systems, these writes may arrive at different replicas in different orders, causing the replicas to diverge and hold conflicting values. Without a ...
The Gossip Protocol is a peer-to-peer communication technique in distributed systems where nodes share information by randomly selecting partners and exchanging state, much like how rumors spread through a social network. It is especially useful in large clusters where nodes frequently join or leave...
Caching is a technique used to speed up data retrieval by placing frequently accessed or computationally heavy information closer to the application or the end user. Below is an expanded set of notes on caching, presented with ASCII diagrams and bullet points that emphasize key considerations. Each ...
A Content Delivery Network (CDN) is a geographically distributed system of servers that deliver web assets such as images, videos, stylesheets, and scripts to users based on their proximity to the nearest server. By placing cached copies of content at strategic locations around the world, CDNs drast...
Locking is about managing concurrent access to shared data. Engineers often make it sound harder than it is, but the core idea is simple: choose between optimistic or pessimistic approaches depending on how costly retries are...
git archive is your clean-room packager. It snapshots exactly what Git tracks at a commit—no .git folder, no stray build junk, no temp files. This means you can hand someone a tidy source bundle or ship code to a server without dragging history along...
Running your own Git server is about owning your source of truth. Your repos live where you decide, under rules you set, at a pace you control. That means you decide who can read and write, how code moves to production, and how the system grows as your team and projects grow. It’s pure Git under the...
Statistics, at its core, is the science of collecting, analyzing, and interpreting data. It serves as a foundational pillar for fields such as data science, economics, and social sciences. An important component of statistics is understanding various distributions or, as some textbooks refer to them...
A vector is a mathematical entity characterized by both magnitude and direction. Vectors are essential in various fields such as linear algebra, calculus, physics, computer science, data analysis, and machine learning. In the context of NumPy, vectors are represented as one-dimensional arrays, enabl...
NumPy provides a set of functions for searching, filtering, and sorting arrays. These operations are helpful for efficiently managing and preprocessing large datasets, enabling you to extract meaningful information, organize data, and prepare it for further analysis or machine learning tasks. This g...
In data manipulation and analysis, adjusting the shape or dimensionality of arrays and matrices is a common task. Reshaping allows you to reorganize data without altering its underlying values, making it suitable for various applications such as data preprocessing, machine learning model input prepa...
In NumPy, arrays are data structures that store elements in a grid-like fashion. Understanding how to access and modify these elements is helpful for efficient data manipulation and analysis. NumPy arrays are 0-indexed, meaning the first element is accessed with index 0, the second with index 1, and...