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Flow: Waiting Queue (Mobile App Only)

Actor

Fan trying to purchase tickets for a high-demand match.

Context

For high-demand matches, HNS expects significant load:

  • Expected Users: 100,000+ fans attempting to purchase
  • Available Tickets: ~20,000 (after quota allocations)
  • Goal: Control access to seat selection & checkout to maintain fairness and system stability

Preconditions

  • Match is on sale (sales activate at scheduled time, e.g., 12:00)
  • User is logged into the HNS mobile app
  • Waiting queue microservice is active (auto-enabled based on traffic demand, not a per-match setting)

Technical Notes

Match Activation Timing:

  • Sales open at a predefined time (e.g., 12:00) configured by admin
  • Mobile app activates "Buy Tickets" / "Join Queue" button at the scheduled time
  • Server-side validation prevents early access (to prevent time spoofing on client)
  • App may use combination of:
    • Client-side timer that activates UI at scheduled time
    • Server validation on queue join request to verify sale is active
    • Push notification at sale start time: "Ticket sales for [Match] are now open!"

Potential Bottleneck - Login/Registration:

  • 100,000+ users may attempt to login/register immediately before ticket release
  • Consider implementing queue for authentication endpoints during high-demand periods
  • Pre-registration campaigns can reduce login surge at sale time

Flow Steps

  1. Join Queue

    • User opens match page in the mobile app
    • App shows status: "High Demand – Join Queue"
    • User taps "Join Waiting Queue"
    • Backend assigns:
      • Queue position
      • Estimated wait time
      • Total queue size
    • A persistent queue banner appears inside the app

  2. Queue Position Display

    • User sees their position: "You are #2,547 in queue"
    • Position updates:
      • Local countdown decrements position every second (smoother UX)
      • Server sync every 60 seconds corrects the actual position
      • This provides responsive feel while maintaining accuracy
    • Displays:
      • Estimated wait time
      • Total queue members
      • Progress indicator
    • User can leave the match screen — the queue remains active

  3. Continue Shopping

    • User can browse the HNS shop while waiting
    • Queue banner remains visible globally:
      • Match pages
      • Merchandise shop
      • Home screen
    • The queue maintains:
      • Active WebSocket/Firebase connection
      • OR background polling fallback

  4. Queue Advancement

    • Backend advances queue when:
      • Users complete purchases
      • Purchase time expires (20 minutes from queue entry)
      • Inventory is released
      • Admins add more quota
    • Backend safely "drip-feeds" users to avoid:
      • Seat allocation spikes
      • Payment load spikes

  5. Progressive Notifications

    • Push notifications for:
      • Position change: "You're now #500 in queue"
      • Near position: "You're almost at the front (#50). Get ready!"
      • Your turn: "It's your turn! Buy tickets for Croatia vs Portugal"
    • User has 20 minutes total from entering the purchase flow to complete the entire transaction (zone selection, checkout, payment)

  6. Purchase Window Opens

  7. Complete Purchase

    • User completes checkout
    • Next queue user is notified
    • If the user fails to complete within 20 minutes:
      • Seats return to inventory
      • Next queue user is notified
      • User loses queue position and must rejoin at the end of the queue

Alternative Flows

A1: User Misses Purchase Window

  • User loses their queue position
  • Must rejoin at the end of the queue (treated as new user)
  • Notification: "Your purchase window has expired. Please rejoin the queue to try again."

A2: User Leaves Queue

  • User clicks "Leave Queue"
  • Confirmation prompt displayed
  • Position is lost permanently
  • Rejoining sends them to back of queue

A3: All Tickets Sold

  • Backend closes queue
  • Push notification: "Match sold out."
  • Queue disbanded automatically

A4: Connection Lost

  • Queue position persists for 30 minutes
  • On reconnect:
    • App restores position
    • Message: "Welcome back! You're still #127 in queue"

A5: Multiple Devices

  • Same user ID = same queue position
  • Device switch transfers the queue session
  • Secondary device shows: "Queue transferred to another device"

Last Updated: January 2026