System requirements

Functional:

There should be an entry and an exit to the parking lot, from different routes, to ensure accessibility for drivers coming and going into the parking area.

The entry and exit times of each vehicle should be marked.

The fee to park a vehicle needs to be calculated and collected at the exit.

A vehicle should be assigned a designated parking space when it receives a ticket, ensuring that all spaces are allocated efficiently and making it easier for the driver to keep track of the vehicle's location.

Non-Functional:

• A UI to monitor the availability of the parking spaces at the entry point of the parking lot.
• A server to receive information on the availability and possible allocations.
• A database to save information about a vehicle's entry time, size, assigned parking spaces, fee charged and exit time.

Capacity estimation

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

If there are 1000 parking lots, each having a capacity of 200 cars.

If we assume that every hour, 100 vehicles enter and 100 exit,

In one day, there would be around 2400 vehicles which would use the parking space,

So, to have data saved for around 2 years, we need to save around 365 * 2 * 2400 = 1,752,000 vehicle entries.

Having a moderate database size and cache storage should do the

job.

Such that we can have the currently active vehicle's entry in both db and the cache, and for those who have left there data will be transferred to the db.

API design

Define what APIs are expected from the system...

• Getting all the spaces that are being used
• Getting vehicle info at a particular parking space
• Getting all the active vehicles' data
• Getting an assignable spot depending on the vehicle type
• Marking the Entry of a vehicle
• Marking the Exit of the vehicle
• Marking the collected fee amount

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...

We can use a relational database for this case, having a table for each date,

With a dedicated column for vehicle number, vehicle type, entry time, fee, exit time and parking spaces assigned.

And Id can be a unique string created using vehicle number + time + date

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?