2.1 System Requirements

Functional Requirements

Non-Functional Requirements

Example: Design a scalable, highly available, and fast messaging system

Thought process

we need to scale for writes and reads, since every message will be written to the messaging system and consumed at some later point
to scale the system for writes, i will need to partition messages, store them in multiple queues
which partition strategy should I use? maybe a hash strategy
where do I store messages quickly? Memory or disk
if using a memory, it can be a bounded queue
if using disk, i can use either an append-only log, or an embedded database
if using database, should I pick a B+ tree or LSM tree? B+ trees are used for fast search and insertion, LSM trees are used when we have write-intensive datasets and reads are not that high, since messaging queues doesn't require search, we'll use LSM tree