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?

mjohnsullivan

// Parsing arbitrary JSON using interfaces in Go
// Demonstrates how to parse JSON with abritrary key names
// See https://blog.golang.org/json-and-go for more info on generic JSON parsing

package main

import (
	"encoding/json"
	"fmt"
)

tsaqib

Ideas

I have collected and moderated these ideas from various public sources and put into one place so that problem solvers and solution developers may find inspirations. Because I wish to update it regularly, I have setup as a single page wiki. You may try these ideas on hackathons/competitions/research; some are quite intense problems and some are not. Many of the problems were prepared keeping Dhaka/Bangladesh in mind, but of course can be applied to just about any underdeveloped/developing and sometimes developed countries.

Categories:

• Eradicate Extreme Poverty and Hunger
• Education
• Healthcare
• Governance

xrstf

Info

This guide sets up a non-clustered Nutch crawler, which stores its data via HBase. We will not learn how to setup Hadoop et al., but just the bare minimum to crawl and index websites on a single machine.

Terms

• Nutch - the crawler (fetches and parses websites)
• HBase - filesystem storage for Nutch (Hadoop component, basically)

vishaltelangre

Concept

• People talk about two servers: a web server (e.g. Nginx, Apache, etc.) and a app server (e.g. Language specific servers like Unicorn, Node.js, Tomcat, Http-Kit, etc.). There are exceptions where app servers not required at all (as web server itself provides preprocessors for handling), but let's not talk about now.
• Web servers are really fast and supports lot of standard and commonly used MIME-type requests. Concept of serving a file is -- forming and sending a response of bytes of data and labeling it with requested MIME-type by a client (e.g. web browser).
• Every response format (in layman's language, a file) is recognized by it's MIME-type, for e.g. a PNG image file has "image/png" MIME-type. JavaScript file has "text/javascript". HTML responses (or files) has "text/html". Plain text files have "text/plain".
• Modern Browsers supports a lot of standard MIME-types. Images, videos, text files (XML, HTML, SVG, JS), and they better know how to visualize it. Browser also knows unrec

drorata

# Initialize the scroll
page = es.search(
  index = 'yourIndex',
  doc_type = 'yourType',
  scroll = '2m',
  search_type = 'scan',
  size = 1000,
  body = {
    # Your query's body
    })

Kartones

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

• -E: will describe the underlaying queries of the \ commands (cool for learning!)
• -l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

ianfleeton

// Save this as MineSweeper.java
// compile with this command
// javac MineSweeper.java
// then run with this command
// java MineSweeper

// We need this for random numbers.
import java.util.Random;

class MineSweeper {

timtadh

#!/usr/bin/env python
# Copyright (c) 2012, Tim Henderson
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# - Redistributions of source code must retain the above copyright notice,
#   this list of conditions and the following disclaimer.

tuananh

---
layout: default
title: Archive
---

<div class="post">
	<h2>Archive</h2>
	<ul>
	  {% for post in site.posts %}
	    {% unless post.next %}