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How to Use the OSI Model Simulator: A Step-by-Step Tutorial
Getting started with the OSI Model Simulator takes less than 60 seconds. The interface is thoughtfully designed to be intuitive for beginners while offering enough depth to satisfy advanced learners. Here's your complete step-by-step guide. Step 1: Open the Simulator Navigate to app.osi-model-simulator.roboticela.com in any modern web browser. No account required, no download necessary, and no cost. The app loads instantly and is ready to use immediately. Alternatively, visit the landing page to learn more about features and download the desktop app for offline use. Step 2: Enter Your Message In the message input field, type any text you like. This is the "data" your simulation will encapsulate. Examples: Hello, World! GET /index.html HTTP/1.1 {"user": "alice", "action": "login"} Your own name or a phrase you'll remember Using a personally meaningful message makes the encapsulation feel real rather than abstract. Step 3: Choose Your Protocol Select from five real protocols: HTTP, HTTPS, SMTP, DNS, or FTP. Each choice changes the Application Layer headers added to your data. For beginners, start with HTTP. Then re-run with HTTPS to see the Presentation Layer encryption difference. Step 4: Choose Your Transmission Medium Select your Physical Layer medium: Ethernet, Wi-Fi, Fiber Optic, Coaxial, or Radio. This affects how the Physical Layer is visualized at the end of the simulation. Step 5 (Optional): Set Custom IP Addresses For a more realistic Network Layer demonstration, enter a source IP address (simulating your device) and a destination IP address (simulating the server). This makes the Layer 3 packet header concrete and personally relevant. Step 6: Run the Simulati on Click the Run or Start button. Watch as your message travels through all seven layers: Application Layer adds protocol headers Presentation Layer adds encryption (if HTTPS) Session Layer adds session management Transport Layer segments and adds TCP/UDP header Network Layer wraps in IP packet Data Li
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Ethernet, Wi-Fi, Fiber, Coaxial & Radio: Transmission Media Compared
The Physical Layer's choice of transmission medium profoundly affects the performance, cost, security, and reliability of a network. The OSI Model Simulator supports all five major media types — making it a powerful tool for understanding how physical choices ripple up through all seven OSI layers. Medium Speed Max Distance Security Cost Ethernet Up to 10 Gbps+ 100m (Cat6a) High (physical access) Low Wi-Fi Up to ~9.6 Gbps (Wi-Fi 6) ~100m indoor Medium (WPA3) Low Fiber Optic Terabits/s 100s of km Very High High Coaxial Up to 1 Gbps 500m (RG-8) Medium Medium Radio Variable (5G: Gbps) km to global (satellite) Low–Medium Variable Ethernet: The Reliable Standard Ethernet is the dominant wired networking standard in homes, offices, and data centers. Using twisted-pair copper cables (Cat5e, Cat6, Cat6a), it provides reliable, high-speed connectivity with predictable latency. The IEEE 802.3 standard governs Ethernet, and modern variants include 1GbE, 10GbE, 25GbE, 40GbE, and 100GbE. Wi-Fi: Wireless Freedom Wi-Fi (IEEE 802.11) eliminated the need for physical cables in most consumer settings. Wi-Fi 6 (802.11ax) and Wi-Fi 6E deliver impressive speeds, but shared medium access, interference, and radio propagation challenges mean it will never fully replace wired Ethernet for critical applications. Fiber Optic: The Internet's Backbone Fiber optic cables carry data as pulses of light through glass or plastic strands. They're immune to electromagnetic interference, support enormous bandwidth, and can span continents — literally. Every major internet exchange, submarine cable, and data center interconnect uses fiber. Coaxial Cable: The Cable TV Legacy Coaxial cable — familiar from cable TV connections — consists of a central conductor surrounded by insulating layers and a braided metal shield. DOCSIS-based cable internet connections (common from ISPs like Comcast) use coaxial as the last-mile medium. Radio: Wireless at Scale From the cellular 5G network in your pocket to satellite
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Deeper into Dataform 3: Auditing Dataform
It's important to monitor Dataform - jobs executed by Dataform can be the primary source of BigQuery costs in a modern data platform. Forgetting to incrementalise a table, using a table instead of a view in the wrong place or performing complex window functions on a large table can all incur large costs and long run times. Using the WorkflowInvocationAction for each job we can extract its BigQuery Job ID, then extract key metadata for each BigQuery job by querying INFORMATION_SCHEMA.JOBS_BY_PROJECT , before writing the output back to BigQuery so that it can be analysed (maybe even by transforming it in Dataform). from google.cloud import dataform_v1 from google.cloud import bigquery from datetime import datetime # ------------------------------------------------------------ # CONFIG # ------------------------------------------------------------ PROJECT_ID = " my-project " REGION = " europe-west2 " REPOSITORY_ID = " analytics " WORKFLOW_INVOCATION_ID = " 123456789 " BQ_REGION = " region-europe-west2 " OUTPUT_TABLE = " my-project.raw_dataform_monitoring.raw_dataform_bigquery_metrics " # ------------------------------------------------------------ # CLIENTS # ------------------------------------------------------------ dataform = dataform_v1 . DataformClient () bq = bigquery . Client ( project = PROJECT_ID ) repository = dataform . repository_path ( PROJECT_ID , REGION , REPOSITORY_ID ) invocation_name = f " { repository } /workflowInvocations/ { WORKFLOW_INVOCATION_ID } " # ------------------------------------------------------------ # 1. GET WORKFLOW INVOCATION ACTIONS → EXTRACT JOB IDS # ------------------------------------------------------------ job_ids = set () actions = dataform . list_workflow_invocation_actions ( parent = invocation_name ) for action in actions : # only BigQuery actions contain job metadata if hasattr ( action , " bigquery_action " ) and action . bigquery_action : if action . bigquery_action . job_id : job_ids . add ( action . bigquery_action
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Here comes new Siri again
Apple has been on its back foot, AI-wise, for the past few years. But in a strange way, playing from behind might not be such a bad move. At WWDC on Monday, Apple appears to be getting ready to reintroduce us to the new Siri. Again. As a reminder, we met the new Siri in […]
产品设计
The next YouTube phenomenon hitting the big screen
Hi, friends! Welcome to Installer No. 131, your guide to the best and Verge-iest stuff in the world. (If you're new here, welcome, happy last week of productivity before the World Cup starts, and also you can read all the old editions at the Installer homepage.) This week, I've been reading about the World Cup […]
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how to make the "mimic"
if youve been on the internet long enought you probably know vommitedthoughts a person that created the mimic irl and he can talk to it and it replies very human like, so ive been wanting to make my own chatbot like that called kira but idk how my last experience with python chatbots failed since it was SO dumb and it started talking to itself so how do i make my own chatbot that i can constimize its personality ?? submitted by /u/i_am_X-Kira [link] [留言]
科技前沿
Some ancient microbes frozen with Ötzi the Iceman are still growing
What’s the difference between a person, an artifact, and an ecosystem?
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Stride
The AI workspace that plans, designs and ships with you. Discussion | Link
开发者
Anti-Vax Dating Apps Are Going IRL. People Are Mad as Hell About It
Unjected and PureBlood.Dating are hosting in-person meetups—and have transformed the dating landscape into a political battleground over bodily autonomy.
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The Best 3-in-1 Apple Charging Stations After Testing Top Models
I tried all the top models to find the best 3-in-1 Apple charging stations, pads, and more. Keep your iPhone, Apple Watch, and AirPods topped up with these WIRED-tested docking systems.
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Learn Agentic AI with quick, easy to run hands on labs, visual canvases and notebooks for free!
If you’re a full-stack engineer or technical architect willing to learn production-grade enterprise agents, you need architecture, security, and type-safe systems. That’s why we built AgentSwarms.fyi —the ultimate hands-on educational platform for teaching agentic AI and multi-agent workflows. 🚀 The Core AgentSwarms Ecosystem: Real-World Architectures: Skip the generic hello-world loops. Learn production-grade systems like human-in-the-loop validation, automated multi-platform content multiplexers, and secure code-sandbox environments. Deterministic Cloud Guardrails: Deep dives into multi-cloud token economics, dynamic cost-optimized routing, and model evaluation metrics. Grassroots Engineering Focus: No corporate marketing fluff. Just raw, practical code patterns designed to bridge the gap between fragile prototypes and stable cloud deployments. 💣 The New Drop: 60+ Browser-Native TypeScript Notebooks We just completely re-engineered our learning workspace. We’ve added 60+ fully interactive TypeScript Notebooks running 100% natively in your browser. No pip install dependency hell, no local Docker setup, and zero environment friction. Read the architecture, tweak the system prompts or Zod schemas, hit play, and watch the streaming terminal execute live across the five absolute best frameworks in the ecosystem: 🟢 LangChain.js (Fundamentals & Middleware Guardrails) 🔀 LangGraph.js (Cyclic Graphs & Stateful Orchestration) 💾 LlamaIndex.ts (Sentence-Window Retrieval & RAG Triad Evals) ⚡ Vercel AI SDK (Streaming UI Integration) 🤖 OpenAI Agents SDK (Lightweight, low-boilerplate loops) Stop passively scrolling through video courses. Open a canvas, break the graph nodes, and start compiling real multi-agent swarms. 👉 Dive in for free: agentswarms.fyi/learn submitted by /u/Outside-Risk-8912 [link] [留言]
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2 Best Bluetooth Trackers of 2026, Plus Honorable Mentions
These are the best Bluetooth, Wi-Fi, GPS, and cellular gadgets to ensure you never lose anything ever again.
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Crypto-Funded Chinese Peptide Labs Are Booming
Plus: Hackers use Meta’s AI bots to hack Instagram accounts, Anthropic helps NSA hackers, a decades-long GPS satellite mystery may have been solved, and more.
科技前沿
Velotric Nomad 2 Fat Tire Ebike, Tested and Reviewed (2026)
This wide-tired bike rolls comfortably over dirt, gravel, and whatever curbs you happen to bounce down.
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How to Share a Link to a Particular Phrase
Modern browsers let you share a link that jumps straight to whatever text you wish to highlight. Here’s how the feature works.
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5 Principles of Survival for Software Engineers
5 Principles of Survival for Software Engineers Adapted from Leon Business School's "5 Principles of Survival" Your stack won’t save you. Your principles will. In the wild, survival isn’t about having the best gear. In software, survival isn’t about having the absolute best framework. It’s about how you operate when production is on fire, the roadmap shifts overnight, and AI just turned your "moat" into a weekend hobby project. Here are 5 core principles that keep you alive in modern software engineering. 1. 🔥 Adapt or Perish Change is not optional; it is the price of survival. In the wild: The species that cannot adapt to winter dies. In software: The team that cannot adapt to change dies slowly at first, then all at once. "Localhost is for amateurs" used to be a strongly held belief. Now, Claude writes a full CRUD API in 30 seconds on localhost . "We’re a React shop" was a proud identity. Now, HTMX ships the same feature before your Webpack build even finishes. Your identity as an engineer cannot be tied to a specific tool. Your identity is solving problems . The syntax is temporary. Agreement on what to build is what actually matters. 🛠️ Survival Action Every quarter, deliberately kill one "we’ve always done it this way" rule in your workflow. 2. 🧭 Stay Calm Under Pressure Panic is the first casualty of poor preparation. In the wild: Panic burns critical calories and gets you lost. In software: Panic causes a git push --force to main on a Friday at 4:59 PM. Outages don’t kill companies. Panicked responses do. The team that has clear runbooks, relies on feature flags, and can execute a rollback in under 90 seconds stays calm. Why? Because they prepared when it was quiet. If your first step in incident response is opening X (Twitter) or complaining in a public Slack channel, you have already lost. 🛠️ Survival Action If you don't have a tested rollback plan, you don't have a deployment plan. Write it down before your next release. 3. 💡 Resourcefulness Over Resources
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peektea brews on WSL 👀🍵 (and installs in one line)
Hello, I'm Maneshwar. I'm building git-lrc, a Micro AI code reviewer that runs on every commit. It is...
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From ThreadPoolExecutor to httpx AsyncClient: True Async Refactoring
Published on : 2026-06-06 Reading time : 6 min Tags : #python #async #performance #optimization The Problem: Fake Async The supabase-async library claimed to be async but actually wrapped synchronous calls with ThreadPoolExecutor: # ❌ Fake async (old code) class SupabaseAsync : def __init__ ( self ): self . _executor = ThreadPoolExecutor ( max_workers = 3 ) async def select ( self , table : str ): loop = asyncio . get_event_loop () r = await loop . run_in_executor ( self . _executor , lambda : requests . get ( url ) # Sync call wrapped as async ) return r . json () Problems : Max 3 concurrent requests (not scalable) Thread overhead per request High memory usage No connection pooling Solution: httpx AsyncClient Use true async HTTP with httpx: # ✅ Real async (new code) import httpx class SupabaseAsync : def __init__ ( self ): self . _client : Optional [ httpx . AsyncClient ] = None async def _get_client ( self ) -> httpx . AsyncClient : if self . _client is None : self . _client = httpx . AsyncClient ( headers = self . _headers , timeout = 30 , limits = httpx . Limits ( max_connections = 10 ) ) return self . _client async def select ( self , table : str ): client = await self . _get_client () r = await client . get ( f " { self . _base } / { table } " ) r . raise_for_status () return r . json () Performance Gains Metric ThreadPoolExecutor(3) httpx(10) Max concurrent 3 requests 10 requests Avg response 450ms 150ms Memory usage 250MB 180MB Throughput 6.7 req/s 20 req/s Real benchmark : 100 concurrent requests ThreadPoolExecutor: 15 seconds httpx AsyncClient: 5 seconds 3x faster ⚡ Migration Steps 1. Client Initialization with Lazy Loading async def _get_client ( self ) -> httpx . AsyncClient : if self . _client is None : self . _client = httpx . AsyncClient ( headers = self . _headers , timeout = 30 , limits = httpx . Limits ( max_connections = 10 , max_keepalive_connections = 5 ) ) return self . _client 2. HTTP Methods (GET, POST, etc.) async def _request ( self , metho
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How to Escape and Unescape JSON Strings (Quotes, Backslashes, Newlines & Unicode)
If you've ever hit Unexpected token in JSON at position 42 or Unterminated string , there's a good chance an unescaped character broke your payload. JSON is strict about what's allowed inside a string, and the fix is almost always escaping . Here's the practical version. What does escaping a JSON string mean? A JSON string is wrapped in double quotes. Any character that would confuse the parser must be replaced with a backslash escape sequence. Escaping doesn't change the meaning of your text — it just makes the string valid JSON so parsers can read it. Unescaping is the reverse: turning those sequences back into readable characters (handy when you copy a value out of logs or an API response). The characters you must escape JSON defines exactly seven characters that must be escaped inside a string: Character Escaped as Double quote " \" Backslash \ \\ Newline \n Carriage return \r Tab \t Backspace \b Form feed \f The forward slash / may optionally be escaped as \/ , but it isn't required. Unicode can be written as \uXXXX (four hex digits). JSON escape examples Double quotes — He said "hello" becomes: "He said \" hello \" " Backslashes (Windows paths) — C:\temp\file.txt becomes: "C: \\ temp \\ file.txt" Newlines and tabs — a two-line, tabbed string becomes: "Line 1 \n Line 2 \t Tabbed" How to escape and unescape JSON in code In production you rarely escape by hand — every language has it built in. JavaScript const escaped = JSON . stringify ( text ); // escape const back = JSON . parse ( escaped ); // unescape Python import json escaped = json . dumps ( text ) # escape back = json . loads ( escaped ) # unescape Java (Jackson) ObjectMapper mapper = new ObjectMapper (); String escaped = mapper . writeValueAsString ( text ); String back = mapper . readValue ( escaped , String . class ); C# (.NET) using System.Text.Json ; string escaped = JsonSerializer . Serialize ( text ); string back = JsonSerializer . Deserialize < string >( escaped ); Common escaping mistakes (and f
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# Next MDL Update: Security-First Adapters and HTMX Support
In the last update, I introduced MDL as an HTML-first language for building websites and apps with less noise. This update is about the next layer: adapters . The goal is simple: MDL source should describe intent. Adapters decide how that intent becomes deployable HTML. Why adapters? I don’t want MDL to become locked into one frontend framework. Instead, the same MDL structure should be able to target different deployment styles: static HTML MDL-native runtime attributes HTMX future template or framework adapters So this: form@api(post /api/login)@result(loginResult)@swap(replace): .input@type(email)@required .btn-primary@type(submit)(Sign in) status@id(loginResult): Waiting. Can become plain HTML: html <form method= "post" action= "/api/login" > Or HTMX: html <form hx-post= "/api/login" hx-target= "#loginResult" hx-swap= "outerHTML" > Security before convenienceThe important part is that MDL does not pass behavior attributes through blindly. Raw HTMX attributes like this are blocked: mdl form@hx-post(/api/login): Instead, MDL uses intent-based attributes: mdl form@api(post /api/login): Then the adapter validates and translates it. Current safety rules include: external api(...) URLs are rejected raw @hx-* attributes are blocked raw browser events like onclick(...) are blocked unsafe URL schemes like javascript: are blocked broad form inclusion like @params( ) is blocked @inherit( ) is blocked @disinherit(*) is allowed because disabling inherited behavior is safer That means MDL can support HTMX without making MDL source depend directly on HTMX’s full raw surface area. New HTMX adapter attributesThe HTMX v2 adapter now supports more behavior attributes: mdl @select-oob(...) @swap-oob(...) @disabled(...) @disinherit(...) @encoding(...) @history-elt(...) @inherit(...) @params(...) @preserve(...) @prompt(...) @replace(...) @request(...) @sync(...) @validate(...) Example: mdl form@api(post /api/profile)@result(profileResult)@swap(replace)@params(email csrfToken)@disable