Detailed component design

The long URL's will be converted to short URL by using the key generation service
Each URL will be converted to short URL and each of them will be hased using the key-value so that its easy to write/read and look up
What is Key Generation Service?
The KGS is a standalone Database by itself which will generate a key for each URL every time we get a request
This way it will prevent the duplicate keys or eliminate the collision of keys
How to generate 6 letter keys offline
We will generate using base 64 algorithm
The Base 64 Encoding algorithm has 64 characters, hence the name. By implementing the Base 64 Encoding, it became possible to transmit 8 bit ASCII
base 64 generates 8 letter code which will generate 281 billion unique strings
we will use 6 letter code which will generate 68 billion unique strings and that will suffice this requirement
What happens if we generate offline
By generating offline we might miss some of the key's
if the server goes down then we might waste some of the keys
concurrency issue might be a concern
Failure - Keeping all keys in one server will be single point of failure hence its good to have one in each server
How to find the key
we can look up the key-value and if the URL is there then redirect it using http 302 code and if not available then use the code 404 - as not found

Caching

No longer need to perform management tasks such as hardware provisioning, software patching, setup, configuration, and failure recovery
Have access to monitoring metrics so you can diagnose and react to issues quickly
Can take advantage of cost-efficient and resizable hardware capacity

Purging/clean up

Load balancers

round robin method
what comes in will go out and sequentially processed one at a time
Use AWS load balancer to automatically manage the traffic during the peak traffic

Rate Limiter

Fault tolerance

KGS is a single point of failure
Horizontal sharding to include leaders/followers servers
if the leader dies then follower will take it over
distribute the servers across multi-locations and incase of dynamo db they are multi-region