CEOehis

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

CEOehis

const CENTS = 100;

function toCents(amount) {
  return Math.ceil(amount * CENTS);
}

function toUSD(amount) {
  return amount / CENTS;
}

CEOehis

function telephoneCheck(str) {
  // Good luck!
  const numberRegex = /^((\(\d{3}\)[ -]?)|(\d{3}[ -]?))\d{3}[ -]?\d{4}$/;
  // check if it starts with 1
  if(str.startsWith('1')) {
    return numberRegex.test(
      str.substring(1).trim()
    );
  }
  return numberRegex.test(str);

CEOehis

function toPascalCase(text) {
  text = text.trim();
  return text.replace(/(\w)(\S*)(\s*)/g, // matches words and spaces
    function(g0,g1,g2){
      return g1.toUpperCase() + g2.toLowerCase();
    }
  );
}

CEOehis

brew cask install android-file-transfer \
  google-chrome \
  appcleaner \
  caffeine \
  cheatsheet \
  docker \
  doubletwist \
  1password \
  spectacle \
  superduper \

CEOehis

What are microservices

• An approach to developing a single application as a suite of small services
• Independently deployable, using automated deployment tools
• Enable apps to be built by multiple teams using multiple tech stacks

Advantages

• They help decrease the cost of change
• Works very well in Devops context

CEOehis

Algorithmic Complexity

It is important to try as much as you can to get the order of complexity of your algorithms to be higher up the following heirachy than lower.

• O(1): constant time
• O(log n): logarithmic
• O(n): linear
• O(n log n): loglinear
• O(n^C): polynomial
• O(C^n): exponential

CEOehis

function getCurrentPosition() {
  if (navigator.geolocation) {
    return new Promise((resolve, reject) => {
      navigator.geolocation.getCurrentPosition(resolve, reject);
    });
  } else {
    return Promise.reject('geolocation is not available on this device');
  }
}

CEOehis

brew cask install android-file-transfer
brew cask install
    appcleaner
    caffeine
    cheatsheet
    docker
    doubletwist
    flux
    1password
    spectacle

CEOehis

brew cask install \
caskroom/fonts/font-3270-nerd-font \
caskroom/fonts/font-3270-nerd-font-mono \
caskroom/fonts/font-abel \
caskroom/fonts/font-aboriginal-sans \
caskroom/fonts/font-abril-fatface \
caskroom/fonts/font-acme \
caskroom/fonts/font-allura \
caskroom/fonts/font-anonymouspro-nerd-font \
caskroom/fonts/font-anonymouspro-nerd-font-mono \