Design a Pay-Per-View Event System

Problem statement

Design a pay-per-view platform that sells one-time access to a live streaming event — a boxing match, a UFC card, a wrestling supercard, or a one-off concert. A user buys a pass, the system records that entitlement, and at the scheduled start time the user can watch the live stream. The access is ephemeral: it is valid only during the event window, may be limited to one concurrent device, and may include a short post-event video-on-demand window before the rights expire.

This is not Netflix. A subscription system answers 'does this account have a membership?' once and caches it for hours. A PPV system answers 'does this exact user own a valid, unexpired, unrevoked pass for this exact event, right now, on this device?' continuously, under a brutal and predictable load spike, while the content itself is guarded by DRM and geo-rights. The money is concentrated into a single night. If the paywall fails open, the promoter loses millions to piracy. If it fails closed at 10:59 PM, a paying customer misses the walkout and the support line melts.

Why the problem is distinctive

Three properties separate PPV from general streaming. First, demand is spiked and time-boxed. Purchase volume and concurrent playback are both dominated by the hour around the main event, not spread across a day. The system must absorb a thundering herd of entitlement checks and playback starts within a narrow window. Second, the asset is high-value and leakable. A live fight is worthless ten minutes after it ends, so piracy and credential-sharing are existential. Access must be enforced per-device and per-session with short-lived cryptographically signed tokens and DRM licenses, not just a boolean flag. Third, the purchase is a financial transaction under concurrency pressure. A customer must never be double-charged, a canceled event must trigger reliable refunds, and entitlement granting must be exactly-once even when the payment gateway retries.

The problem requires a purchase flow with secure token generation, event scheduling, real-time streaming with limited concurrency checks, an optional short VOD window, autoscaling for the spike, payment integration with refunds, DRM to prevent restreaming, and possible geo-restrictions. The section rhythm, recap contract, multi-cloud diagrams, and Interview Buddy rules follow the orchestrator and core spec.

The four architectural planes

1. Commerce plane: catalog, event scheduling, checkout, payment capture, refund, and the durable purchase ledger.
2. Entitlement plane: the source of truth for who owns what, expressed as signed, expirable grants that can be revoked.
3. Delivery plane: live ingest, encoding, packaging, DRM license issuance, CDN distribution, and per-session concurrency enforcement.
4. Governance plane: geo-rights policy, fraud and anti-piracy monitoring, audit evidence, and observability.

A strong answer keeps these planes separate. A payment outage must not stop an already-entitled viewer from playing. A DRM license-server hiccup must not corrupt the purchase ledger. And a concurrency violation detected in the delivery plane must be enforceable without a round trip to the commerce database.

Public baseline versus design assumptions

Public reporting establishes the category. UFC 229 (Khabib Nurmagomedov vs. Conor McGregor, October 2018) generated roughly 2.4 million PPV buys, an MMA record. Mayweather vs. Pacquiao in 2015 reached about 4.6 million buys and well over $400 million in PPV revenue alone. DAZN signed Canelo Alvarez to a reported $365 million, 11-fight contract and is built on AWS. WWE Network moved its US library to Peacock in 2021. These are cited public figures that prove the market is real; every capacity number used for sizing below is an explicitly stated design assumption, not a claim about any company's private architecture.