System requirements

Functional:

List functional requirements for the system (Ask the chat bot for hints if stuck.)...

• cars can go into the parking lot, get a ticket, park in the spot
• keep track of open spots
• keep track of the type of spots (disability, compact, electrics, normal)
• keep track of cars that enter and exit
• keep track of costs per hour (enter and when exit times)

Non-Functional:

List non-functional requirements for the system...

• Consistency: ensure parking availability of the space
• Availability: having it open at all times to enter and exit
• Latency: not as important, can a few seconds at kiosks
• Scalability: national usage, 50 states, 5 per state, 250 garages in total

Capacity estimation

Estimate the scale of the system you are going to design...

Storage:

250 garages

5 floors

100 spots

100 * 5 * 250 =125,000 spots in total

1MB of data for each spot

125,000 * 1 = 125,000 MB

Bandwidth:

125,000 * 100 * 2 = 250,000,000 requests per day

API design

Define what APIs are expected from the system...

REST

PUT garage/parkingspaceid/entering

paramaters:

garageid

parkingspaceid

timestamp

carid

GET garage/availablespace/spacetype

parameter:

garageid

spacetype

return:

garagid

parkingspaceid

PUT garage/parkingspaceid/exiting

parameters:

garageid

parkingspaceid

timestamp

carid

return

price

Database design

Defining the system data model early on will clarify how data will flow among different components of the system. Also you could draw an ER diagram using the diagramming tool to enhance your design...

relational database

garage table:

garageid: unique indentifier

spots table:

garage_id: foreign key

spot_id: unique identifier

time_stamp: string

spot_type: string (handicapped, normal, compact, electric)

occupied: boolean

High-level design

You should identify enough components that are needed to solve the actual problem from end to end. Also remember to draw a block diagram using the diagramming tool to augment your design. If you are unfamiliar with the tool, you can simply describe your design to the chat bot and ask it to generate a starter diagram for you to modify...

Request flows

Explain how the request flows from end to end in your high level design. Also you could draw a sequence diagram using the diagramming tool to enhance your explanation...

Detailed component design

Dig deeper into 2-3 components and explain in detail how they work. For example, how well does each component scale? Any relevant algorithm or data structure you like to use for a component? Also you could draw a diagram using the diagramming tool to enhance your design...

Trade offs/Tech choices

Explain any trade offs you have made and why you made certain tech choices...

Failure scenarios/bottlenecks

Try to discuss as many failure scenarios/bottlenecks as possible.

Future improvements

What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?