Putting It Together: a fundamental approach to system design

Foundations of Practical System Design

System Design Course for Junior Engineers

Kay Ashaolu

Lesson Overview

• We go over how we will introduce a new way of approaching system design through case studies
• These case studies, and the technology agnostic Building Block approach is formulated to inspire "Senior level intuition" for junior engineers
• Intuition is built when seeing the same Building Blocks used in different case studies

Recap: From Bits to Systems

• Everything in our digital world breaks down to zeros and ones.
• At the lowest level, data is either:
  • Stored (as sequences of zeros and ones) - Storage units
  • Processed (instructions that transform or utilize those zeros and ones) - Task units

Fundamental Building Blocks

• Combine storage and tasks to create meaningful components.
• These components (building blocks) can be servers, databases, or other well-known constructs.
• Each building block exists to fulfill a specific purpose in the system.

Intuition Over Specifics

• The purpose of this course is to develop intuition, not to memorize implementations.
• By understanding the building block concept, you can reason about any system, regardless of technology specifics.
• This intuition helps you adapt, compare, and even switch technologies when necessary.

The Next Step: 15 Case Studies

• We will explore 15 different applications you interact with in everyday life.
• Each case study:
  1. Presents requirements and what we want to build.
  2. Shows how to compose Building Blocks (Task units + Storage unit) to meet those requirements.
• Seeing many examples builds strong intuition, just like in real life.

Starting With Requirements

• Real-world system design starts with defining requirements.
• You determine what the system should do, who uses it, what it stores, and what tasks it performs.
• The case studies will simulate this process:
  • Read the prompt.
  • Understand the scenario.
  • Identify key needs.

Matching Requirements to Building Blocks

• Once requirements are known, we combine Building Blocks to meet them.
• We introduce Building Blocks as the combination of Task units (computation, logic) + Storage units (data persistence, structure).
• Over time, you’ll see patterns: certain Building Blocks appear repeatedly to solve common problems.

Not About the "Best" Design

• There are many valid ways to design a system.
• We focus on understanding the fundamental reasoning process:
  • Identify what you need to store.
  • Identify what tasks you need to perform.
  • Utilize the best Building Blocks to architect your system

Identifying Patterns in Systems

• After examining multiple examples, you’ll recognize repeating patterns:
  • Common Building Blocks appear in different contexts.
  • Similar trade-offs and considerations emerge regardless of the domain.

Building Long-Term Intuition

• Study all 15 case studies to develop a deep, flexible intuition.
• Refer to the provided guide under this video listing Building Blocks and their real-world technology counterparts.
• Over time, you’ll understand:
  • What each technology really provides.
  • How to swap or adjust building blocks as needs evolve.

Your Next Steps

• Approach each case study with an open mind.
• Key: Focus on the Building Block concepts rather than think about which specific technology implements those building blocks
• With each example, grow your intuition, making you more confident and versatile in system design.