Trippers Network - System Design(ru | eng)

Trippers.net - a social network for travelers

Functional Requirements

• Posting travel posts with photos, a brief description, and geotagging to specific travel destinations;
• Rating and commenting on posts by other travelers;
• Following other travelers to track their activity;
• Searching for popular travel destinations and viewing posts from these locations;
• Viewing the feed of other travelers.

Non-Functional Requirements

• DAU 10,000,000
• Availability: 99.9% (4h 23m) per year
• Usage location - worldwide
• Seasonality: tourism is twice as active in summer
• Posts are stored - permanently
• Number of subscriptions/followers - unlimited
• One post - one photo
• Post:
  - Photo: 1mb
  - Description: 200 characters (utf-8)
  - Location: Location ID
  - Number of reactions: 4 bytes
• Location: Latitude + Longitude + Radius
• Comment: 140 characters (utf-8)
• Reaction: Reaction (1 byte) + post ID (16 bytes)
• Feed loading time - no more than 5 seconds
• User feed load: up to 20 posts
• Popular locations load: up to 10 locations
• Posts from popular locations load: up to 20 posts
• Comments from posts load: up to 20 comments
• User views feed 5 times a day
• User uploads 1 post every 5 days
• User reads comments only on one post per day
• User leaves 1 comment per day
• User reacts to 3 posts per day

Basic calculations

• Post:
  - RPS(write): DAU * (1/5) / 86400 = ~23rps
  - RPS(read): DAU * 5 / 86400 = ~580rps
  
  - Traffic(text write): 25 * ( 200(description) * ~2(utf8) + 4(locationID)) = ~10kb/s
  - Traffic(text read): 580 * (200 * ~2(utf8) + 4(locationID) + 4(number of reactions)) = ~231kb/s
  
  - Traffic(media write): 25 * 1mb = ~25mb/s
  - Traffic(media read): 580 * 1mb = ~580mb/s
  
• Comments:
  - RPS(write): DAU * 1 / 86400 = ~115rps
  - RPS(read): DAU * 1 / 86400 = ~115rps
  
  - Traffic(write): 115 * 1 *(140 * ~2(utf8)) = ~31kb/s
  - Traffic(read): 115 * 20 * (140 * ~2(utf8)) = ~628kb/s
  
• Reactions:
  - RPS(write): DAU * 3 / 86400 = ~347rps
  
  - Traffic(write): 347 * 16(post ID) = ~5.4kb/s
  

Concurrent Connections Calculation

• Connections: DAU * 0.1 = ~1 000 000