How to Build a Real-Time Notification System Using Server-Sent Events in Python

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A tutorial published on DEV Community explains how to replace inefficient HTTP polling with Server-Sent Events (SSE) for real-time browser notifications. SSE allows a server to push updates to clients over a single, persistent HTTP connection without the complexity of WebSockets. The guide uses Python with Flask to build two endpoints — one for clients to listen on and one to trigger new notifications. An in-memory list manages active connections in the demo, with Redis Pub/Sub recommended for production scalability. The tutorial highlights SSE as a lightweight, browser-native solution suited for one-way server-to-client use cases like alerts and order updates.

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Step-by-Step Guide: Build a React To-Do App Connected to Supabase

A beginner-friendly tutorial published on DEV Community walks developers through connecting a React application to Supabase, an open-source backend-as-a-service platform. The guide targets those with basic React knowledge and requires no prior Supabase experience to follow along. It covers setting up a Supabase project, creating a PostgreSQL todos table, and integrating the Supabase JavaScript client into a Vite-based React app. The tutorial demonstrates full CRUD functionality — creating, reading, updating, and deleting tasks — using Supabase's auto-generated APIs. Security considerations such as Row Level Security and environment variables for API keys are also briefly addressed.

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ProgrammingDEV Community ·

intervals-icu Library Offers Typed TypeScript Client for Intervals.icu API

An open-source TypeScript package called intervals-icu provides a structured, typed client for interacting with the Intervals.icu training API. The library, now at version 2.2.1, organizes API operations by resource type—such as athletes, activities, wellness, and events—rather than exposing a single large interface. It supports both API key and OAuth authentication, handles transient failure retries automatically, and requires Node.js 18 or newer with ESM module support. Developers can install the package via npm, initialize a client with credentials stored as environment variables, and query athlete data with minimal boilerplate code. The repository is publicly available under the MIT license, and the tutorial focuses on establishing a maintainable client foundation rather than building a full training application.

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ProgrammingDEV Community ·

AI Can Accelerate Legacy Modernization but Cannot Replace Engineering Judgment

Legacy modernization involves far more than rewriting old code — it requires managing risk across critical business processes, hidden dependencies, and undocumented logic. AI tools can assist teams by explaining old code, generating documentation, mapping dependencies, and detecting duplicate logic, saving significant discovery time. However, AI lacks the broader context needed to determine which components should be rewritten first, which architecture is appropriate, or which risks are acceptable. Engineers must still validate AI-generated insights, since legacy systems often embed undocumented business rules, client-specific exceptions, and operational workarounds. The core message is that AI is a useful accelerator during modernization, but strategic and architectural decisions continue to require human engineering judgment.

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ProgrammingDEV Community ·

Why Software Should Never Replace a Missing Time with a Default Value

A software engineer writing for DEV Community argues that substituting a missing time field with a default value like midnight or noon silently converts unknown data into false facts. The problem is especially consequential in domains such as medical timelines, legal deadlines, and astrological calculations, where the hour of an event can materially change the outcome. The author illustrates the issue through a BaZi chart pipeline, where inserting a fallback birth time makes output appear complete while undermining its accuracy. To preserve the distinction between observed and inferred data, the article recommends using a discriminated union type that forces downstream code to explicitly acknowledge when a time value is unknown. The approach is presented as language-agnostic, applicable across TypeScript, Rust, databases, and data-serialization formats.

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