Paul pjchavarria

System Design Cheatsheet

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

Basic Steps

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?

Deploying Parse Server on AWS

Note: this is a work-in-progress and will be updated with more information over the next few days.

Intro

This guide will walk you through deploying your own instance of the open-source Parse Server. This would be a good starting point for testing your existing application to see if the functionality provided by the server is enough for your application, and to potentially plan your migration off the Parse Platform.

This guide will walk you through using Elastic Beanstalk (EB), which is an AWS service similar to Heroku. Why use EB rather than Heroku? Elastic Beanstalk does not lock you into Heroku-specific ways of doing things, is likely cheaper to run your backend on than Heroku, and it integrates with other services that AWS offer (and they offer almost everything one needs to run an application these days).

Add the URL of the framework's repo to your Cartfile using one of the following:

  github "ReactiveCocoa/ReactiveCocoa" # GitHub.com
  github "https://enterprise.local/ghe/desktop/git-error-translations" # GitHub Enterprise
  git "https://enterprise.local/desktop/git-error-translations2.git"
  git "/Users/user/foo/bar.git"

…optionally followed by one of the following version specifiers:

	const waitFor = (ms) => new Promise(r => setTimeout(r, ms))
	const asyncForEach = async (array, callback) => {
	for (let index = 0; index < array.length; index++) {
	await callback(array[index], index, array)
	}
	}

	const start = async () => {
	await asyncForEach([1, 2, 3], async (num) => {
	await waitFor(50)

	require 'net/http'
	require 'json'
	require 'uri'

	@token = ''

	def list_files
	ts_to = (Time.now - 30 * 24 * 60 * 60).to_i # 30 days ago
	params = {
	token: @token,

	- (void)imagePickerController:(UIImagePickerController *)picker
	didFinishPickingMediaWithInfo:(NSDictionary *)info
	{
	NSURL *assetURL = info[UIImagePickerControllerReferenceURL];
	ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];

	[assetLibrary assetForURL:assetURL resultBlock:^(ALAsset *asset) {
	ALAssetRepresentation *representation = [asset defaultRepresentation];

	Byte buffer = (Byte )malloc(representation.size);

	#import <UIKit/UIKit.h>


	@interface SwipeNavigationController : UINavigationController <UIGestureRecognizerDelegate>

	@property (nonatomic, readonly) NSArray *poppedViewControllers;

	- (void)clearPoppedViewControllers;

	@property (nonatomic, readonly) UISwipeGestureRecognizer *leftSwipeGestureRecognizer;

	# xcode-build-bump.sh
	# @desc Auto-increment the build number every time the project is run.
	# @usage
	# 1. Select: your Target in Xcode
	# 2. Select: Build Phases Tab
	# 3. Select: Add Build Phase -> Add Run Script
	# 4. Paste code below in to new "Run Script" section
	# 5. Drag the "Run Script" below "Link Binaries With Libraries"
	# 6. Insure that your starting build number is set to a whole integer and not a float (e.g. 1, not 1.0)

	//This is an example of how to scrape the web using PhantomJS and jQuery:
	//source: http://snippets.aktagon.com/snippets/534-How-to-scrape-web-pages-with-PhantomJS-and-jQuery
	//http://phantomjs.org/

	var page = new WebPage(),
	url = 'http://localhost/a-search-form',
	stepIndex = 0;

	/**
	* From PhantomJS documentation:

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD