Return machines should log accept, store and payout as separate events

·1 views

A bottle-return machine that records a single "recycled" entry can produce false records when its network connection fails. The proposed fix splits each visit into three device-verifiable events: accept, when a container is matched and committed locally; store, when the container is actually retained; and payout, when the deposit or reward is issued. Accept should be saved on the device before any mechanical movement, keyed by machine ID and a local sequence rather than a server clock. A payout that fails because the scheme API is down should be queued without rolling back the accept, and replays after reconnection should return the original IDs to avoid double payment or lost containers.

Read the full story at DEV Community

This is an AI-generated summary. ShortSingh links to the original source for the complete article.

Discussion (0)

Why One Developer Switched From WebSockets to SSE for Live Dashboards

While building a Node.js dashboard that needed live updates without page refreshes, the author initially assumed WebSockets were the right tool. On closer analysis, the dashboard only required one-way data flow from server to browser, so the bidirectional capability of WebSockets went unused. Server-Sent Events run over standard HTTP, use the browser's native EventSource API, and avoid the manual lifecycle and heartbeat management that WebSockets demand. The article notes SSE integrates easily with existing proxies and load balancers, benefits from HTTP/2 multiplexing, and handles reconnection natively. The author concludes that protocol choice should follow the direction of data flow rather than update frequency alone.

0 comments Read more at DEV Community

ProgrammingDEV Community ·

Network Latency Could Corrupt Robot Training Data, Researchers Argue

A recent paper introduces K-AoI, a metric that measures how closely a digital twin stays synchronized with the physical scene during remote robot operation. It combines data age with spatial alignment rather than relying on delay alone. The authors argue that remote teleoperation sessions produce recorded demonstrations used to train future autonomous robots, so frames with stale views may be unreliable. The piece also notes that trained human annotators must review such footage frame by frame before it becomes usable training data.

0 comments Read more at DEV Community

ProgrammingDEV Community ·

Guide Outlines a Reviewable JSON Workflow for Designing D&D Encounter Maps

A technical planning guide describes how to design D&D encounter maps by starting with clear requirements and ending with a table-ready export that others can review. It frames the map as a working model of space that shows movement, sightlines, route choices, and how the environment changes during play. The author recommends a tool-neutral JSON brief that records grid scale, required zones, routes, and hazards, and shows a small validator that flags incomplete briefs before visual review. The guide notes that its examples are synthetic and that AI-generated drafts still require human judgment about scale, access, and clarity. It also stresses that the validator checks only explicit values and does not prove a map is playable.

0 comments Read more at DEV Community

ProgrammingDEV Community ·

Un desarrollador crea una web que unifica los horarios de transporte de Valencia

Un vecino de Valencia cansado de consultar tres webs distintas para moverse en transporte público ha desarrollado horariosvlc.es, una plataforma gratuita y sin registro. Permite buscar una parada, estación o línea y consultar el tiempo que falta para el siguiente servicio. La web combina datos de FGV, EMT, Renfe, la Generalitat Valenciana y el Ayuntamiento, y se actualiza cada madrugada. El proyecto se mantiene con donaciones y detalla la procedencia y licencia de cada fuente, señalando también que las tarifas se revisan manualmente.

0 comments Read more at DEV Community