vasanthk

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?

jorinvo

You got your hands on some data that was leaked from a social network and you want to help the poor people.

Luckily you know a government service to automatically block a list of credit cards.

The service is a little old school though and you have to upload a CSV file in the exact format. The upload fails if the CSV file contains invalid data.

The CSV files should have two columns, Name and Credit Card. Also, it must be named after the following pattern:

YYYYMMDD.csv.

nolanlawson

// Promise.all is good for executing many promises at once
Promise.all([
  promise1,
  promise2
]);

// Promise.resolve is good for wrapping synchronous code
Promise.resolve().then(function () {
  if (somethingIsNotRight()) {
    throw new Error("I will be rejected asynchronously!");

justmoon

'use strict';

module.exports = function CustomError(message, extra) {
  Error.captureStackTrace(this, this.constructor);
  this.name = this.constructor.name;
  this.message = message;
  this.extra = extra;
};

require('util').inherits(module.exports, Error);

genadyo

{
    "491289025" : "ijinshan-kappmarket://",
    "301521403" : "fb103361823069955://",
    "492178411" : "ils492178411://",
    "346142396" : "fb234434003713://",
    "310633997" : "whatsapp://",
    "370614765" : "com.condenet.newyorker://",
    "325058491" : "rnmddisco://",
    "382952264" : "epichttp://",
    "477048487" : "predictwind://",

kachayev

Channels Are Not Enough

... or Why Pipelining Is Not That Easy

Golang Concurrency Patterns for brave and smart.

By @kachayev

Intro

staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---

rhythmus

Proposal for a lightweight, database-less, general purpose, name-based file management app

First draft, Easter Sunday 2014

In line with current trends toward lean and simple software solutions reviving and repurposing long-established standards (open plain text vs proprietary rich text formats; file-based static site generators vs bloated database-driven CMSs), the present proposal inquires into a method (and its application) to device a lightweight, general-purpose solution for small-scale digital asset management.

No database is to be used, there shall be no external dependencies, all information carriers should be self-containing, and everything would be file-based. The software would build on a (yet to be established) convention of file naming, which would store metadata for arbitrary files inside the file name, advancing its portability across platforms.

Put as a — somewhat far-fetched — YC-style one-liner pitch: this proposal is about *

samwize

// # Mocha Guide to Testing
// Objective is to explain describe(), it(), and before()/etc hooks

// 1. `describe()` is merely for grouping, which you can nest as deep
// 2. `it()` is a test case
// 3. `before()`, `beforeEach()`, `after()`, `afterEach()` are hooks to run
// before/after first/each it() or describe().
//
// Which means, `before()` is run before first it()/describe()

mjhm

#! /usr/bin/node

var MongoClient = require('mongodb').MongoClient
var Server = require('mongodb').Server;
var async = require('async');
var util = require('util');

// A simple linear congruence random number generator.
// This is anticipating doing a comparable test with the aggregation pipeline.
var randMod = 2 << 24;