System requirements
Functional:
List functional requirements for the system (Ask the chat bot for hints if stuck.)...
- creating tweets (text)
- track other users (for you page, following)
- favorite tweets
Non-Functional:
List non-functional requirements for the system...
- consistency: weaker side, delay for tweets
- performance: quickly as possible
- availability: 24/7
- latency: few secs
Capacity estimation
Estimate the scale of the system you are going to design...
bandwidth:
1 million users
1 once a day of tweeting
1 million tweets a day = 1 million requests per day
2 hours a day
10 secs refresh fyp
6 refreshes or requests per hour
24 * 6 = 150 requests day
150 milion requests per day
storage:
each tweet:
- tweet_id, user_id, like_count, body
- 1MB per tweet
1 million tweets a day
365 days
365 milllion MB per tweet
365,000 GB
365 TB
API design
Define what APIs are expected from the system...
REST
POST /twitter/userid/body
parameters:
user_id: unique identifier
body: string
time_stamp: string
return:
status_code: 200Ok, 400-500 error
GET /twitter/userid
parameters:
user_id: unique identifier
return:
user_id: unique identifier
user_name: string
tweet_id: unique identifier
body: string
like_count: int
time_stamp: string
PUT /twitter/tweetid
parameters:
tweet_id: unique identifier
return:
like_count: int
status_code: 200OK, 400-500 error
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:
user:
user_id: unique identifier
user_name: string
followers: list [user_id]
tweets: list [tweet_id]
tweet:
tweet_id: unique identifier
user_id: foreign key
like_count: int
time_stamp: string
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?