Fullstack Tiny URL Service

:fist: A full-stack web application, developed by MEAN Stack, that generates short URL and shows the statistics data of the usage of the short URL; Enhanced independence by deploying Docker and improved QPS by using Redis as cache and Nginx as reverse proxy.

Attriumph
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JavaScript

Fullstack-Tiny-URL-Service

Design steps：SNAKE principle —— crack a design in 5 steps

1. Scenario： use case/interface

  • shortURL insert（longURL）
  • longURL lookup（shortURL）re-direct

2. Necessary: constraint /hypothesis

We assume daily active user： 1,000,000

  • (1) average estimate

    • for Insert：

      • per day: 1,000,000*1%（function usage）*10(function frequencey) = 100,000
      • RPS : 100,000/86400 = 1.2

    • for Lookup：

      • per day： 1,000,000*100%(function usage)*3(function frequency)= 3,000,000
      • RPS : 3000000/86400=35

  • (2) peek estimate:

    • Assume peak traffic = 5* Average daily traffic
    • insert peek : 1.2 *5 = 6
    • lookup peek： 35 *5 = 175

    Therefore, we can deal with it by a single machine

3. Aplication: service/algorithm

  1. In oder to design efficiently, we use map at the begin(ShortToLongMap， LongToShortMap)
    map<longURL, shortURL> LongToShortMap;
    map<shortURL, longURL> ShortToLongMap;
    
    shortURL insert(longURL){
       if LongToShortMap not containsKey longURL:
           generate shortURL;
           put<longURL, shortURL> into LongToShortMap;
           put<shortURL, longURL> into ShortToLongMap;
           return LongToShortMap(longURL);
           }
       
       longURL lookup(shortURL){
       return ShortToLongMap.get(shortURL);
       }
  1. how to generate shortURL？

The simplest way: return map.size()，but the size will increase too big, so we need add letters.
Therefore, we need to convert decimal into 62 hex. Here is the code:

   shortURL generateShortURL(){
          return convertTo62(ShortToLong.size());
   }
   
   shortURL convertTo62(mapSize){
       char encode[62] = {'a',...'z','A',...'Z','0',...'9'};
       shortURL = "";
       while(mapSize != 0){
           shortURL = encode[mapSize % 62] + shortURL;
           mapSize /= 62;
       }
     return shortURL;
   }
  1. introduce a table to replace two maps

4. Kilobit: data

According to experience, we can assume:

  • Average size of long url = 100 byte

  • Average size of short url = 4 bytes(int)

  • Daily new URL = 104 * 100,000 = 104,000,000 byte = 104mb

  • Year new URL = 104mb * 365 = 37960mb < 40GB

    Therefore, singe Machine can handle!

5. Evolve：update and modify

  • How to support random?
    • random(0,range)
  • How to avoid conflicting?
    • try again
  • How to implement time-limited service?
    • expire/state
  • How to cache?
    • pre-load + replacement

Summary：

summary