System Design Basics

Before designing a System

1. Clarify the system requirements and agree on the scope of system.
2. User Cases
   • who will be using it
   • how they are going to use it
3. Constraints
   • traffic and data handling constraints at scale
   • scale of the system(req/s, req types data write/s, data read/s)
   • other requirements such as multi-threading, read or write oriented
4. Abstract Design(High-level architectures)
5. Sketch the important components and connections between them
   • application service layer
   • list of required services
   • data storage layer
   • load balancers, service partitions, database(master/slave db clusters), caching system
6. Component Design
7. component + API
8. object oriented design
   • map features to modules
   • relationship among modules:
   • singeletons (uniq instance)
   • compositions (made up of many other objects)
   • inheritance
   • Database Schema Design
9. Understanding Bottlenecks