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The Everyday Backend Engineer: Step 10 — The Observer Pattern
Welcome back to The Everyday Backend Engineer: Practical Design Patterns . In our last post, we made our core algorithms interchangeable using the Strategy Pattern. Today, we close out our design patterns roadmap with arguably the most native pattern in the entire Node.js ecosystem: The Observer Pattern . Let’s look at how to master event-driven decoupling to trigger secondary workflows seamlessly without bloat. 🔴 The Problem: Direct Inline Side-Effects Imagine you are writing a video processing engine or a simple order fulfillment system. When a specific event happens—such as an order being finalized—multiple unrelated departments want a piece of the action: The Notification Service needs to send an SMS and Email receipt. The Logistics Service needs to generate a warehouse fulfillment ticket. The Analytics Service needs to update marketing tracking boards. If you don't decouple these events, your primary execution service ends up managing a giant web of secondary micro-services: // ❌ Bad Practice: The primary service is drowning in secondary dependencies const EmailService = require ( ' ../services/email ' ); const WarehouseService = require ( ' ../services/warehouse ' ); const AnalyticsTracker = require ( ' ../services/analytics ' ); class OrderProcessor { async finalizeOrder ( order ) { console . log ( " Saving primary order to the database... " ); // Core business logic ends here // The codebase smell: Procedural cascading dependencies await EmailService . sendReceipt ( order . userEmail ); await WarehouseService . createShipment ( order . id ); await AnalyticsTracker . trackSale ( order . totalAmount ); } } module . exports = OrderProcessor ; Why does this slow your system down? Your core OrderProcessor is now structurally dependent on three separate systems. If the AnalyticsTracker throws a network timeout error or if the warehouse API changes its interface, your core transaction fails or hangs. Furthermore, adding a fourth side-effect (like an auditing logger
科技前沿
States sue to block Paramount/WBD merger that was approved by Trump admin
AG: Deal will bring "higher prices, lower quality, and less content for film and TV."
创业投融资
12 states sue to block Paramount’s $110B Warner Bros. deal
The states allege that the deal would harm movie theaters, basic cable distributors, and audiences.
开发者
Lessons Learned from CISA’s Recent GitHub Leak
The Cybersecurity and Infrastructure Security Agency (CISA) has issued a postmortem on a data leak in which a contractor published dozens of internal CISA credentials -- including AWS Govcloud keys -- in a public GitHub repository for almost six months before being notified by KrebsOnSecurity. Experts say the gaps identified in the agency's initial response provide important lessons that all security teams should absorb.
AI 资讯
The graph nobody is watching
If you ask me what part of the system I protect the most, the answer is the database. I've been writing software alone for twenty-four years, and across every platform I've built, the rule has stayed the same: the web servers can take whatever you throw at them, the batches can be rebuilt, but the database has to stay idle on purpose. Not because I love idle databases, but because the day a database actually starts to struggle is a day with very few good options. This article is about what "keep the database idle on purpose" actually means in practice, and about one particular kind of graph that, in my experience, almost nobody is watching. The three layers and what each of them gets I think of a production system as having three tiers, and each tier gets a different rule. The web server tier can be horizontally scaled. If load grows, you add machines. If something is wrong, you take a machine out of the pool, and the others handle it. Failures here are visible immediately, and they're cheap to recover from. The batch server tier can be scaled up or out depending on the work. A batch that's too slow can be split. A batch that crashes can be retried. End users don't see batch servers, so a stuck batch is a problem for me and not for them. Some headroom up here is fine. The database tier is the one I treat completely differently. The database is not where you absorb load. The database is what you protect from load. The reason is simple: the other tiers can be rebuilt or re-scaled. The database is the irreplaceable record. If it slows down, everything slows down. If it falls over, you don't have many minutes before the rest of the stack notices. So my rule for the database is: keep it idle. Not idle in the sense of "doing nothing." Idle in the sense of "running well below its capacity, at all times, so that any extra load it picks up has somewhere to go." For more than a decade I ran a large appliance-grade database where I kept the load average below 1 at all times. N
开发者
Python Is So Slow. Can Julia Solve the Two-Language Problem?
By some benchmarks, Julia code can run 10X to 1,000X faster than Python—but there’s a reason it’s not a very popular programming language.
产品设计
Start Building for Agents, Not Just Humans
For decades, software was designed around one assumption: A human would be the one using it. That...
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Mi INSERT tardaba 25 minutos y no era culpa de los datos: construyendo un Data Warehouse de e-commerce con PostgreSQL
Cargar 112.647 filas en una tabla de hechos debería tardar segundos. A mí me tardaba más de 25 minutos, y acababa cancelando la query. Los datos estaban bien, el SQL estaba bien, las dimensiones se poblaban sin problema. El culpable era otro, y descubrirlo fue la parte más instructiva de todo el proyecto. Todo esto surgió construyendo un Data Warehouse en estrella sobre datos reales de e-commerce: no una tabla bonita para hacer un SELECT * , sino un modelo dimensional completo, reproducible desde cero, capaz de responder preguntas de negocio de verdad. El dataset Trabajé con el Brazilian E-Commerce Public Dataset by Olist : pedidos reales de un marketplace brasileño entre septiembre de 2016 y octubre de 2018. Son 9 CSV relacionados entre sí: 99.441 pedidos y 112.650 líneas de venta 103.886 pagos y 104.719 reseñas 32.951 productos, 3.095 vendedores 1.000.163 registros de geolocalización Y con trampas de datos reales que hay que ver antes de que te muerdan: Un pedido puede tener varios pagos y varias reseñas. Si los unes tal cual a la tabla de hechos, duplicas ventas . Es el error clásico y silencioso: los totales salen inflados y nadie se entera. customer_id no es un cliente. Olist crea uno por cada pedido; la persona real es customer_unique_id . Contar mal aquí te cambia el KPI: hay 99.441 cuentas frente a 96.096 personas. El CSV de productos trae una errata en la cabecera ( product_name_lenght , con "lenght"). Si tu esquema la escribe bien y cargas por interfaz gráfica (que empareja por nombre ), esas columnas se quedan vacías sin que nadie avise. El proceso Monté una arquitectura en capas: CSV → staging → modelo dimensional → vistas → análisis , todo en cuatro scripts ejecutables en orden y idempotentes (el esquema se recrea desde cero, se puede relanzar mil veces). El modelo es un star schema : una tabla de hechos fact_sales al grano de línea de producto dentro de un pedido , y cinco dimensiones (cliente, producto, vendedor, pago y fecha), con claves sustitutas,
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The First Microcontroller Was the TI TMS1000 (1974)
Ask most people to name the chip that started modern electronics and they will say the microprocessor. But there is a quieter hero inside almost everything you own that beeps, blinks, or connects to the internet: the microcontroller. And the first one you could actually buy shipped in 1974 as the Texas Instruments TMS1000. Microprocessor vs. microcontroller The distinction matters. A microprocessor, like Intel's famous 4004, is just the processing core. To build anything useful with it you still have to wire up separate memory chips, input/output controllers, and support logic on a circuit board. A microcontroller collapses all of that onto a single piece of silicon: the CPU, the ROM that holds your program, the RAM that holds your data, and the I/O pins that talk to the outside world, all in one package. That is exactly what the TMS1000 did. Designed by Texas Instruments engineers Gary Boone and Michael Cochran, it was a 4-bit device using a Harvard architecture, meaning it kept program memory and data memory in separate spaces so it could fetch an instruction and read data at the same time. One chip in, one chip out, and you had a complete tiny computer dedicated to a single job. Cheap enough to put in everything The genius of the TMS1000 was not raw power, it was economics. In 1974 you could buy the chips in volume for around two dollars each. By 1979, Texas Instruments was selling roughly 26 million of them every year. That price point changed what engineers could build. Suddenly it made sense to drop a small, programmable brain into products that never would have justified a full computer. You have almost certainly held one. The TMS1000 family ran the Speak & Spell, the Big Trak programmable toy vehicle, and the electronic memory game Simon, along with countless calculators, microwave ovens, and appliances. Each one was doing the same fundamental thing an IoT node does today: read some inputs, run a fixed program, drive some outputs. Why this still matters for
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Failure Engineering Explained by Uncle to Nephew — Episode 2: Types of Failures
Episode 1 established the mindset: failure is normal, not a sign of bad engineering. Episode 2 gets specific — you can't detect or handle a failure you can't even name. Saturday, Round 2 👦 Nephew: Uncle, last time you convinced me failure is basically guaranteed. Fine, I accept it. So what actually fails ? 👨🦳 Uncle: You tell me. Start listing things that could go wrong in your app right now. 👦 Nephew: Uh... the server could crash. The database could go down. My code could have a bug. 👨🦳 Uncle: Keep going. 👦 Nephew: The network? Someone could deploy the wrong thing? Payment gateway dies mid-checkout? 👨🦳 Uncle: You just named six of the seven categories without trying. You already know this. You've just never sorted it. 1. Hardware Failure 2. Software Failure 3. Network Failure 4. Database Failure 5. Third-Party Failure 6. Human Error 7. Resource Exhaustion 👦 Nephew: Then why do we need the list at all, if I already know it instinctively? 👨🦳 Uncle: Because "instinctively" isn't fast enough at 2 AM. Let's trace each one properly. Part 1 — Hardware Failure 👦 Nephew: This one's obvious anyway — I deploy to AWS. The cloud hides hardware failure from me. 👨🦳 Uncle: Does it? 👦 Nephew: ...doesn't it? That's the whole point of paying for EC2 instead of buying a server. 👨🦳 Uncle: Let's trace it. Your app sits on an EC2 instance. What's underneath the instance? 👦 Nephew: Virtual machine stuff, I guess? 👨🦳 Uncle: And underneath that ? 👦 Nephew: ...an actual physical machine somewhere. In a data center. 👨🦳 Uncle: There it is. Your app | "Virtual" server (EC2/Droplet) | ACTUAL physical hardware somewhere in a data center | Still capable of failing — just less visible to you 👦 Nephew: So it's not hidden. It's just one layer further away than I thought. 👨🦳 Uncle: Exactly. AWS absorbs a lot of it — that's part of what you're paying for — but disks still fail, instances still get abruptly terminated, whole availability zones still go down. That's Hardware Failure . Hardware Fa
开发者
Equality Operators (==, !=) in Java — Part 1
Equality operators are among the most frequently used operators in Java. They allow us to compare two values and determine whether they are equal or not. Unlike relational operators ( < , > , <= , >= ), equality operators work with all primitive data types , including boolean , and they can also compare object references . However, many beginners get confused about how == behaves with objects, strings, and null . These concepts are also some of the most frequently asked Java interview questions. Let's understand them with simple explanations and practical examples. What Are Equality Operators? Java provides two equality operators. Operator Description == Equal to != Not equal to Both operators always return a boolean value. Example System . out . println ( 10 == 10 ); System . out . println ( 20 != 10 ); System . out . println ( 5 == 8 ); Output true true false Rule 1: Equality Operators Work with All Primitive Types Unlike relational operators, equality operators can be applied to every primitive type , including boolean . Supported primitive types include: byte short int long float double char boolean Numeric Examples System . out . println ( 10 == 20 ); Output false System . out . println ( 'a' == 'b' ); Output false System . out . println ( 'a' == 97 ); Output true Explanation 'a' = 97 (Unicode) 97 == 97 ↓ true System . out . println ( 'a' == 97.0 ); Output true Even though one operand is a char and the other is a double , Java performs numeric promotion before comparison. Boolean Example System . out . println ( true == false ); Output false System . out . println ( false == false ); Output true Unlike relational operators, equality operators fully support boolean values. Equality Operators vs Relational Operators Many beginners confuse these operators. Expression Result true == false ✅ Valid true != false ✅ Valid true > false ❌ Compile-time error true < false ❌ Compile-time error Remember: Equality operators work with boolean . Relational operators do not. Rul
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Introducing Soterios: An Open‑Source Windows Security/Maintenance Suite (Contributors Welcome)
For the past few weeks, I have been building Soterios , an open-source, local-first security and system maintenance suite for Windows. The idea started simple: most security tools either lock features behind paywalls or collect unnecessary data. I wanted something different, so I built a privacy-first application with: No telemetry No analytics No network activity unless you explicitly enable it Current Features Malware scanning with ClamAV, quarantine, and reporting Windows security audits Firewall management and network monitoring Credential safety tools with local password checks and breach lookups Process inspection and system maintenance utilities Built With Soterios is built with Electron and Node.js using a modular architecture designed to make future expansion straightforward. Why I'm Sharing It I'd rather build in the open than in isolation. Feedback, ideas, bug reports, and contributions are always welcome. GitHub Repository https://github.com/chrisriv10/Soterios
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Teaching AI Agents to Time-Travel: Building a Temporal Debugging Skill
Your AI agent is confident. It points to line 42 of PaymentService.java . "There's your null pointer exception." You check. Line 42 is a comment. The code was refactored 14 commits ago. The production crash happened 3 hours ago . Your agent just spent 45 minutes debugging ghosts . The Problem: Agents Are Stuck in the Present Every AI coding agent today — Claude Code, Cursor, Copilot, Cody, you name it — operates on the same assumption: The code that matters is at HEAD . But production bugs don't live at HEAD . They live in the commit that was running when the crash happened. That commit is buried under hotfixes, refactors, dependency updates, and feature merges that landed after the incident. HEAD (now) ← Agent analyzes THIS │ ├─ feat: add new payment provider ├─ refactor: extract UserService ├─ fix: handle edge case in checkout ├─ chore: update dependencies │ ▼ a1b2c3d (3 hours ago) ← Bug ACTUALLY lives HERE Your agent confidently finds bugs in code that didn't exist when the crash occurred . The Insight: Git Already Has Time Travel We don't need a time machine. Git has had one for years: git worktree . # Get the commit from 3 hours ago git log --before = "3 hours ago" -1 --format = "%H" # → a1b2c3d4e5f6... # Create an isolated, read-only snapshot at that commit git worktree add /tmp/debug-a1b2c3d a1b2c3d # Now analyze the historical codebase cat /tmp/debug-a1b2c3d/src/PaymentService.java # Clean up when done git worktree remove --force /tmp/debug-a1b2c3d This gives you: ✅ Isolated — doesn't touch your working directory ✅ Parallel — can have multiple historical snapshots simultaneously ✅ Disposable — cleanup is one command ✅ Zero deps — pure Git, works everywhere The Missing Piece: Teaching Agents When to Time-Travel Agents already know git log , git show , git diff , cat , grep . They can analyze code perfectly. What they struggle with : Fuzzy time → commit resolution — "last night", "v2.4.1", "the deploy before the hotfix" Worktree lifecycle management — create,
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This slushie machine was a lifesaver during NYC’s heat wave
Last weekend’s brutal NYC heat wave had me craving a frozen drink almost every afternoon. Normally, that would mean sweating through a walk to 7-Eleven for a slurpee. This time, though, I stayed home and put the new Ninja Slushi Twist to the test. Ninja’s latest slushie machine builds on the popularity of the original […]
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Linux 7.2 Improves Multi-GPU Displays, M3 Support, Mesa Rusticl Defaults Arm Mali
Linux 7.2 Improves Multi-GPU Displays, M3 Support, Mesa Rusticl Defaults Arm Mali Today's Highlights This week's hardware and driver news highlights include critical Linux 7.2 kernel updates for multi-GPU display detection and initial support for Apple M3 Pro/Max/Ultra SoCs. Additionally, Mesa's Rusticl OpenCL implementation now defaults to enabling Arm Mali Panfrost driver support, simplifying GPGPU access on embedded devices. Linux 7.2-rc3 Improves Multi-GPU Display Detection (Phoronix) Source: https://www.phoronix.com/news/Linux-7.3-rc3-Multi-GPU-Fix This update for the Linux 7.2-rc3 kernel targets a persistent issue within multi-GPU setups on x86_64 systems: inconsistent display detection. The patch specifically addresses scenarios where certain graphics cards, particularly in configurations mixing integrated and discrete GPUs or multiple discrete cards, would fail to initialize displays correctly or report their presence erratically to the operating system. This is a crucial fix for users and developers deploying workstations with diverse GPU hardware, ensuring more reliable and stable display outputs without manual configuration workarounds. The improvement lies in refining the kernel's ability to probe and correctly identify active display outputs across various GPU architectures. It directly impacts system boot times and user experience by reducing potential black screens or incorrect display layouts. For enterprise and professional users relying on multiple monitors or specific GPU setups for tasks like rendering or scientific computing, this kernel patch is a significant quality-of-life enhancement, removing a long-standing friction point in Linux graphics stack stability. This contributes to the broader goal of making Linux a more robust platform for high-end graphics and compute workstations. Comment: This is a welcome fix for anyone who's wrestled with inconsistent display outputs on multi-GPU Linux machines; it often means less time debugging Xorg conf
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Git: The Fellowship of the Commit – Best Practices for Solo Devs and Teams
The Quest Begins (The "Why") I still remember the first time I tried to track down a bug that only showed up after midnight. I opened my terminal, typed git log , and was greeted by a wall of commits that read like a toddler’s grocery list: * 7a9c3f1 (HEAD -> main ) fix stuff * 4b2e8a1 update * f1d9c6b wip * 9e3b7d2 more changes * … I spent three hours chasing a regression that turned out to be a one‑line typo in a file I hadn’t touched in weeks. The commit messages gave me zero clues, and the diff was a tangled mess of unrelated changes. I felt like I was wandering through a dungeon without a map, hoping the next room would hold the answer. That night I realized the real monster wasn’t the bug—it was the way I was committing code. My commits were large, vague, and scattered , making every subsequent step (review, revert, bisect) a gamble. If I wanted to keep my sanity (and maybe even enjoy coding again), I needed a better system. The Revelation (The Insight) The turning point came when I read about Conventional Commits —a lightweight convention that gives each commit a clear type ( feat , fix , docs , refactor , test , chore , etc.) and a short, descriptive message. It sounded simple, but the impact was massive: Atomicity – each commit does one thing. Clarity – the message tells you why the change exists, not just what changed. Automation – tools can generate changelogs, version bumps, and even release notes straight from the log. Adopting this felt like discovering a hidden shortcut in a Zelda dungeon—suddenly the whole map made sense, and I could sprint to the boss room with confidence. Wielding the Power (Code & Examples) Before – The Chaos Imagine we’re building a tiny API for user profiles. Here’s what a typical day of committing looked like (messages only, but the diffs were just as messy): $ git log --oneline -5 7a9c3f1 ( HEAD -> main ) fix stuff 4b2e8a1 update profile handler f1d9c6b wip 9e3b7d2 added auth middleware c5d4e3f refactor utils If I needed to ro
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Why Is It Called the Raspberry Pi?
If you have ever wired a sensor to a Raspberry Pi or run your first Python script on one, you have used a device whose name hides two small jokes and one very deliberate design decision. Why is it called the Raspberry Pi? The short answer: "Raspberry" is a nod to a decades-old tradition of naming computers after fruit, and "Pi" is short for Python, the programming language the board was originally built to run. Both halves say something about where the machine came from, and why it went on to become a staple of IoT and embedded development. The fruit tradition behind "Raspberry" The "Raspberry" is not random. In the early decades of personal computing, a surprising number of companies named themselves after fruit. Apple is the obvious one, but there was also Acorn Computers (the British firm whose ARM architecture now sits inside nearly every phone and microcontroller on Earth), Apricot Computers, and Tangerine. When Eben Upton and his collaborators at the University of Cambridge set out to build a cheap computer to teach kids to code, choosing a fruit name placed the project squarely in that lineage. Upton has also cheerfully admitted the name is a bit of a pun, a wink at "blowing a raspberry" and at raspberry pie the dessert. Why "Pi" stands for Python The "Pi" is the part that reveals the machine's original purpose. As Upton has explained in interviews, the plan was to produce a computer that could really only run one thing well: Python. So the "Pi" in the name is a compressed reference to Python . It doubles neatly as a nerdy nod to the mathematical constant, but Python was the driving idea. That original intent matters because it explains the board's whole philosophy. The Raspberry Pi was never meant to be a powerhouse. It was meant to be cheap enough that a student could own one, simple enough that a beginner could learn on it, and open enough that it ran a full Linux operating system with Python ready to go. During development the design grew more capable tha
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How to Thrive (Not Just Survive) as a Developer in the Age of AI
The narrative around Artificial Intelligence and software engineering has shifted dramatically. We are no longer asking if AI will change development, but rather how we change with it. If your value as a developer is tied solely to how fast you can churn out boilerplate code, write standard API endpoints, or memorize syntax, the landscape is becoming challenging. AI can do those things in seconds. However, this isn't a death sentence for the engineering career—it is an evolution. The industry is moving away from pure "code generation" and shifting toward system architecture, integration, and governance. To remain indispensable, you need to know exactly where to direct your energy and what pitfalls to avoid. Where to Focus Your Energy To stay relevant, you must position yourself in the areas where AI struggles: high-level abstraction, complex contextual reasoning, and human leadership. 1. System Design and Enterprise Architecture AI is excellent at writing isolated functions, but it struggles with massive, interconnected systems. Focus on how components interact at scale. Understanding how to slice a monolithic application into resilient microservices, orchestrate microfrontends, or design cloud-native solutions is where the high-value work lies. 2. Code Governance and Quality Assurance With AI generating code at unprecedented speeds, codebases are expanding faster than ever. The world doesn't just need people who can create code; it needs gatekeepers who can validate it. Your role will increasingly focus on setting quality standards, establishing robust CI/CD pipelines, and ensuring that AI-generated code adheres to strict security, compliance, and performance metrics. 3. Mentorship and Team Leadership The influx of AI tools means junior engineers can produce code much earlier in their careers, but they often lack the foundational experience to spot subtle architectural flaws or security vulnerabilities. Senior developers must step up as leaders, guiding less experi
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Why Developers Should Think Beyond Documentation
When learning a new technology, most of us follow a familiar path. We start with the official documentation. Then we search GitHub repositories. We read blog posts. We watch YouTube tutorials. Eventually, we ask an AI assistant when we get stuck. Each resource solves a different problem, and the best developers know when to use each one. Documentation Is the Foundation Official documentation should almost always be your first stop. It tells you how a framework or library is intended to work. The information is usually accurate, maintained, and version-specific. If you're learning React, Next.js, or Node.js, the official docs provide the most reliable starting point. But documentation has limits. It explains what something does, not always why developers use it in real projects. Community Content Fills the Gaps That's where blog posts, conference talks, and open-source repositories become valuable. Experienced developers share: Real-world architecture decisions Common mistakes Performance considerations Debugging strategies Project structure Deployment workflows These practical insights often don't belong in official documentation, but they're essential for becoming a better engineer. AI Has Changed the Workflow AI assistants have become another tool in the developer toolbox. Instead of searching through multiple pages, developers can ask targeted questions like: Why is this hook re-rendering? What's the difference between these two approaches? How can I improve this query? Can you explain this error message? AI doesn't replace documentation. It helps you understand it faster. The most effective workflow is using documentation as the source of truth while letting AI explain concepts, compare approaches, or clarify confusing examples. Build Your Own Reference Library One habit that's improved my productivity is creating a personal knowledge base. Whenever I solve a difficult problem, I write down: The issue Why it happened The solution What I learned Links to relevant
开发者
What made you think, "Why hasn't anyone built a good solution for this yet?" Текст
**_Hi everyone! We're three 16-year-old friends learning to code. Instead of building "just another app," we want to solve a real problem that developers actually face. So we have one question: Think about a moment when you caught yourself saying, "Why hasn't anyone built a good solution for this yet?" What was the problem? It can be anything: something that wastes your time, something frustrating, a repetitive task, a confusing workflow, or anything that made you wish a better tool existed. We're not trying to sell anything. We're simply listening and looking for real problems worth solving. Every answer means a lot to us. Thank you!_**