Problem statement:
Design a URL shortening service
- What do you think the requirements are?
- What is your high level design?
- You might be asked to implement interesting portions
- How do you test it?
Will work on the design very soon.
1. Read the website first: 5 - 10 minutes
stackoverflow.com - how do short urls services work
2. Hired in tech website - the system design process
Step 1: Constraints and use cases
Step 2: Abstract Design
Start from step 1:
System constraints (Do you clarify?)
Use cases ( the list to satisfy?)
Scope system (agree?)
Gather requirements -> design a solution to cover them well.
Use cases:
1. Shortening:
2. Redirection:
3. Custom Url
4. Analytics
5. Automatic link expiration
6. Manual link removal
7. UI or API
And then, discuss and exchange ideas with requirements:
For example, add one more use case 4, and move 4 - 7 out of scope, not for now.
1. Shortening:
2. Redirection:
3. Custom Url
4. High availability of the system
Out of scope:
4. Analytics
5. Automatic link expiration
6. Manual link removal
7. UI or API
Constraints:
Top 10 shorten URL services:
Math to figure out, for example:
15 billion new tweets in twitter,
All shortened URLs per month: 1.5BN - 10 percent
Sites below the top 3: shorten 300M per month
1. New urls per month: 100MLN - 100 millions request to shortening
2.
3.
4.
20% urls generate 80% traffic -> 1BN request per month -> 10% shortening, 90% redirection.
4. Requests per second: 400+ requests per second (40: shortens, 360: redirects)
5. 6BN urls in 5 years -
6. 500 bytes per URL (100 to 1000 characters per URL)
7. 6 bytes per hash
8. 3TBs for all urls, 36GB for all hashes (over 5 years, not 10 years)
9. how much data goes through each second?
New data written per second: 40 *(500 + 6): 20K
10. Data read per second: 360 *506 bytes: 180K
scope the problem beautifully - it takes a while, but 15 minutes in the video, with practice, it takes 5 minutes to clear up everything.
Sept. 3, 2016
Spend 2 hours to watch the video, hiredintech.com, the video link is here. System design - scalability, the link is here.
Take some notes here.
1. Read the website first: 5 - 10 minutes
stackoverflow.com - how do short urls services work
2. Hired in tech website - the system design process
Step 1: Constraints and use cases
Step 2: Abstract Design
Start from step 1:
System constraints (Do you clarify?)
Use cases ( the list to satisfy?)
Scope system (agree?)
Gather requirements -> design a solution to cover them well.
Use cases:
1. Shortening:
2. Redirection:
3. Custom Url
4. Analytics
5. Automatic link expiration
6. Manual link removal
7. UI or API
And then, discuss and exchange ideas with requirements:
For example, add one more use case 4, and move 4 - 7 out of scope, not for now.
1. Shortening:
2. Redirection:
3. Custom Url
4. High availability of the system
Out of scope:
4. Analytics
5. Automatic link expiration
6. Manual link removal
7. UI or API
Constraints:
Top 10 shorten URL services:
Math to figure out, for example:
15 billion new tweets in twitter,
All shortened URLs per month: 1.5BN - 10 percent
Sites below the top 3: shorten 300M per month
1. New urls per month: 100MLN - 100 millions request to shortening
2.
3.
4.
20% urls generate 80% traffic -> 1BN request per month -> 10% shortening, 90% redirection.
4. Requests per second: 400+ requests per second (40: shortens, 360: redirects)
5. 6BN urls in 5 years -
6. 500 bytes per URL (100 to 1000 characters per URL)
7. 6 bytes per hash
8. 3TBs for all urls, 36GB for all hashes (over 5 years, not 10 years)
9. how much data goes through each second?
New data written per second: 40 *(500 + 6): 20K
10. Data read per second: 360 *506 bytes: 180K
scope the problem beautifully - it takes a while, but 15 minutes in the video, with practice, it takes 5 minutes to clear up everything.
Follow up
Sept. 3, 2016
Spend 2 hours to watch the video, hiredintech.com, the video link is here. System design - scalability, the link is here.
Take some notes here.
