A Fake DataChannel That Preserves Backpressure and Close Semantics
Implement a controllable substitute with bufferedAmount, watermarks, message limits, reordering, loss, and close states for fast protocol tests that still match browser contracts.
uCopy Technical Blog
Clear explanations for connections that work in real life · Page 4
Practical uCopy guides to WebRTC, P2P file transfer, STUN and TURN, LAN discovery, resumable transfers, screen sharing, privacy, and security.
WebRTCP2P transferSTUN / TURNPrivacy & security
FIELD NOTES
Subscribe via RSSLatest articles
Measuring Feature Adoption from Exposure Through Repeated Value
Define exposure, intent, technical success, user completion, and repeated value for chat, clipboard, files, and screen instead of treating button clicks as adoption.
File System Access API: Persistent Handles and Permission
Handle file pickers, stored handles, queryPermission, requestPermission, file-change validation, and fallback without overstepping user consent.
A File Transfer Cancellation Protocol That Stops Both Sides
Define terminal state, versions, acknowledgement, and tombstones for local, remote, offline, and timeout cancellation so peers stop promptly and tasks never revive.
Graceful WebSocket Shutdown During Rolling Deployments
Drain traffic, notify clients, provide reconnect hints, set deadlines, and hand off state so rolling deploys do not create duplicate sessions or lose active work.
Honest File Progress: Read, Sent, Acknowledged, or Persisted
Define byte semantics, speed, and ETA across read, sent, acknowledged, resumed, verified, and persisted stages without regressions or false completion.
The HTTP Idempotency-Key Contract Under Retries and Concurrency
Specify key scope, lifetime, request digest, pending conflicts, and response replay so exports, credential issuance, and connection actions retry safely.
Idempotent Signaling Commands for Offer, Accept, and Cancel
Define command IDs, session versions, deduplication windows, and result replay so retries and double clicks cannot create duplicate connections, notifications, or opposing terminal states.
Idempotent Frontend Events Without Duplicate Side Effects
Use message IDs, entity keys, session versions, and terminal states across retries, reconnect replay, duplicate listeners, and repeated clicks so effects run once.
An Incident Runbook That Turns Signals into Recovery Actions
Write executable runbooks for connection failures, TURN overload, analytics 5xx, and stalled files, covering confirmation, scope, mitigation, rollback, communication, and review evidence.
IndexedDB Schema Migrations That Survive Interrupted Upgrades
Design incremental versionchange, idempotent data migration, blocked handling, old-tab coordination, and rollback so users do not get stuck during database upgrades.
IndexedDB Transaction Boundaries for Chunks and Progress
Use transaction auto-commit, asynchronous boundaries, object-store atomicity, and crash recovery so chunks, range manifests, and task states cannot disagree.
IP Pseudonymization with Truncation and Rotating Salts
Support coarse geography, short-term abuse correlation, and capacity analysis without retaining full IPs by combining prefix truncation, HMAC, salt rotation, and access isolation.
Diagnosing IPv6 WebRTC Across Routes, DNS, and Firewalls
Diagnose global, temporary, and ULA addresses, NAT64, Happy Eyeballs, AAAA, and UDP firewalls so broken IPv6 cannot stall dual-stack WebRTC.
Completing File Transfer with a Keyboard from Selection to Cancel
Provide predictable tab order, drag-and-drop alternatives, receive consent, task navigation, progress detail, cancel controls, and focus restoration.
How Browser Device Discovery Works on a Local Network
See why a page cannot freely scan a LAN, how same-exit discovery differs from ICE, and what a complete flow needs from presence and consent through expiry, blocking, and reconnect.
Managing Browser Memory Pressure During Large File Transfers
Transfer large files with sliced reads, transferable buffers, streaming hashes, bounded windows, and memory watermarks while surviving mobile memory reclamation.
Latency Percentiles: When a 100 ms Average Hides Ten Seconds
Collect histograms, p50/p95/p99, timeout-censored data, and cohorts correctly to find tail problems in connect, first-byte, cancel, and recovery flows.
Leases and Heartbeats for Distributed Task Ownership
Use expiring leases, renewal windows, fencing tokens, and takeover rules so paused processes and partitions cannot leave two writers active.
Liveness, Readiness, and Startup Probes Have Different Jobs
Separate dead-process detection, traffic readiness, and startup completion across databases, disk, event loops, degraded dependencies, and draining.
No install. No account.
Start for freeConnect two devices now
Send files, sync a clipboard, chat, and share a screen securely from the browser.