System requirements

Functional:

-create account

-upload plaintext

• link to said text
• ability to set read/write access
• expiration
• timestamp
• created
• updated

-view text

Non-Functional:

-highly available

-eventual consistency

-significantly more reads than writes

Capacity estimation

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

API design

-POST createAccount(email, user, password)

-POST createText(user, text, permissions, expiration) -> returns link to the text

-PUT updateText(user, link, new_text, new_permissions, new_expiration) -> returns link to the text

-GET text(user, link) -> returns text if valid permissions and not expired

Database design

due to the nature of pastebin, sharing large amounts of text, a nosql database would be ideal for sharing the unstructured type of data. Also, having a nosql approach would be better to scale and shard.

-Users

• username
• email
• password (hashed)
• texts
• text_1 link
• ...
• text_n link

-Texts

• metadata
• owner

-expiration

• permissions
• timestamp
• created
• modified
• data
• text

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...

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?