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List functional requirements for the system (Ask the chat bot for hints if stuck.)...
List non-functional requirements for the system...
Estimate the scale of the system you are going to design...
Write operation: 1,000 URLs are generated per second.
Read operation: 10,000 URL visits per second.
Assuming the URL shortener service will run for 10 years, this means we must support
1,000*60*60*24*365*10=315 billion records
Assume average URL length is 100.
Storage requirement over 10 years: 315 billion * 100 bytes = 31.5 TB
Define what APIs are expected from the system...
1.URL shortening.
POST api/v1/data/shorten
• request parameter: {longUrl: String}
• return shortURL
2.URL redirecting.
GET api/v1/shortUrl
• Return longURL for HTTP 301 redirection
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...
Users: Store user information if user accounts are required.
URLs: Store original URLs and their corresponding short URLs.
Clicks: Track clicks on the shortened URLs for analytics.
erDiagram
USER ||--o{ URLs: owns
USER ||--o{ Analytics: views
URLs ||--o{ Clicks: "leads to"
USER {
string id "User ID"
string name "Username"
string email "User's email"
}
URLs {
string id "URL ID"
string original_url "Original URL"
string short_url "Shortened URL"
date created_at "Creation Date"
date expires_at "Expiration Date"
}
Analytics {
string id "Analytics ID"
string user_id "User ID"
string url_id "URL ID"
int total_clicks "Total Clicks"
date last_accessed "Last Accessed Date"
}
Clicks {
string id "Click ID"
string url_id "URL ID"
string visitor_ip "Visitor IP"
string referer "Referer"
date clicked_at "Click Date"
}
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...
flowchart TD
B[client] --> C{API server}
C --> D[Database]
C --> E[URL Parser]
C --> F[Redirector]
G[Generate Auto-incremented ID] --> H[Convert ID to Base62]
H --> I[Create Short URL with Base62 ID
]
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...
sequenceDiagram
User->>+URLShorteningService: Sends URL to shorten
URLShorteningService->>+DataBase:Save original URL
DataBase-->>URLShorteningService:Confirmation
URLShorteningService->>+URLShorteningService:Generate short URL
URLShorteningService-->>User:Short URL generated
URLShorteningService->>Cache:Store Short URL
User->>RedirectService:Accesses short URL
RedirectService->>DataBase:Retrieve original URL
DataBase-->>RedirectService:Original URL
RedirectService-->>User:Redirect to Original URL
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...
Explain any trade offs you have made and why you made certain tech choices...
flowchart LR
A[Client Application] --> B[Load Balancer]
B --> C[Web Server 1]
B --> D[Web Server 2]
C --> E[Database]
D --> E
E --> F[Caching Server]
Try to discuss as many failure scenarios/bottlenecks as possible.
Bottlenecks:
Database Performance: As the number of stored URLs grows, the database might experience performance issues like slow read/write operations or high latency.
URL Generation: Generating unique short URLs efficiently while ensuring they are collision-free can be a bottleneck, especially at high request volumes.
Redirection: Handling an increasing number of redirection requests concurrently might lead to delays in resolving and redirecting to the original URLs.
Monitoring and Logging: Inadequate monitoring and logging mechanisms can make it difficult to identify and debug issues quickly, affecting system reliability.
Scaling: Scaling the system to accommodate growing traffic and data volumes without compromising performance and availability poses a significant challenge.
Failure Scenarios:
High Traffic: A sudden surge in traffic could overwhelm the system, leading to slow response times, service downtime, or even complete system failure.
Data Loss: If the system does not have adequate data backup mechanisms, there is a risk of losing URL mappings in case of hardware failures or database corruption.
Security Breaches: Vulnerabilities in the system could be exploited by attackers to redirect URLs to malicious websites or steal sensitive information.
Long Redirect Chains: Excessive redirections due to multiple short URLs pointing to each other can confuse users and degrade performance.
Expired URLs: If there is no mechanism to handle expired or unused short URLs, the system may become cluttered with outdated mappings.
What are some future improvements you would make? How would you mitigate the failure scenario(s) you described above?'
• Rate limiter: A potential security problem we could face is that malicious users send an overwhelmingly large number of URL shortening requests. Rate limiter helps to filter out requests based on IP address or other filtering rules. \
• Web server scaling: Since the web tier is stateless, it is easy to scale the web tier by adding or removing web servers.
• Database scaling: Database replication and sharding are common techniques.
• Analytics: Data is increasingly important for business success.