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While this loads — quick one
Every subscriber must get each event. A queue, or pub/sub?
Message queueorPub/Sub
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While this loads — quick one
Every subscriber must get each event. A queue, or pub/sub?
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While this loads — quick one
Every subscriber must get each event. A queue, or pub/sub?
System design interview question
YouTube, Netflix, any platform where people upload and watch video: “design a video streaming service” is really two systems. One is a slow, heavy pipeline that turns an upload into something playable; the other serves the same popular files to millions of people at once, cheaply. It tests background processing and delivery at scale. Here is how to walk into it, and then how to practise it until the answer is yours.
Practise Video Streaming
Free with an account.
A video platform lets creators upload recordings of up to several gigabytes, which viewers then watch on phones, laptops and TVs over connections ranging from patchy mobile data to fast fibre. Each upload has to be converted into several resolutions so playback can step down on a slow connection instead of stalling, and that conversion takes minutes per video, far longer than anyone would wait on an upload page. Uploads arrive unevenly, with big spikes after popular events. Most viewing is of a small set of popular videos, watched by millions of people across many countries, and the platform pays for every byte it serves from its own origin.
Every phrase that matters in the brief is a requirement in disguise. Spot them before you draw a single box.
“up to several gigabytes”
Storage built for very large files.
“converted into several resolutions”
Conversion work that produces each resolution.
“far longer than anyone would wait on an upload page”
Put the conversion in line and answer the creator straight away.
“Uploads arrive unevenly, with big spikes”
A line that absorbs spikes and workers that drain it.
“watched by millions of people across many countries”
Serve video from locations near the viewers.
The same design always gets the same score, with the reason behind every requirement — then defend it against the trade-offs above.
“pays for every byte it serves from its own origin”
Let the edge answer most requests, so few bytes come from the origin.
The answers are not on this page on purpose. Build the design, and these are asked — and marked — once it is submitted.
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