Ben Marini bmarini

2015-01-29 Unofficial Relay FAQ

Compilation of questions and answers about Relay from React.js Conf.

Disclaimer: I work on Relay at Facebook. Relay is a complex system on which we're iterating aggressively. I'll do my best here to provide accurate, useful answers, but the details are subject to change. I may also be wrong. Feedback and additional questions are welcome.

What is Relay?

Relay is a new framework from Facebook that provides data-fetching functionality for React applications. It was announced at React.js Conf (January 2015).

Environment

Use Godep to manage dependencies and commit the Godeps/_workspace/src directory so the build will always compile it when you come back six months later.

Style

Read through https://code.google.com/p/go-wiki/wiki/CodeReviewComments. Don't be clever, just follow the community guidelines.
Install goimports. Have it run automatically when you save a file in your editor.
Install go vet. Also have it run when you save a file. It will catch a lot of typos in comments.

This article has been given a more permanent home on my blog. Also, since it was first written, the development of the Promises/A+ specification has made the original emphasis on Promises/A seem somewhat outdated.

You're Missing the Point of Promises

Promises are a software abstraction that makes working with asynchronous operations much more pleasant. In the most basic definition, your code will move from continuation-passing style:

getTweetsFor("domenic", function (err, results) {
 // the rest of your code goes here.

Get Mountain Lion and Homebrew to Be Happy

After upgrading to Mountain Lion, I got this message when trying to run my local rails server:

Installing rmagick (2.13.1) with native extensions
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

    Users/user/.rvm/rubies/ruby-1.9.3-rc1/bin/ruby extconf.rb

If you prefer VirtualBox or aren't running OS X, here are some instructions and a script to help you get started with SmartOS under VirtualBox. If you use VirtualBox, skip the first section and read the section on how to get the Node.js SmartMachine up and running.

Running SmartOS under vmware Fusion

Start by downloading the latest live image
When you run the new VM wizard, select "Continue without disk" on the first screen of the wizard.
Select Sun Solaris / Solaris 10 64-bit on the next screen.
You're going to get dumped to a config screen when the live image starts up, choose DHCP for the networking and defaults for everything else.
Pretty much the first thing you're going to want to do is figure out how to SSH into the box once it boots and creates its storage pools, because trying to do stuff in the virtual console is miserable. There's no cut and paste

Here are some resources that I found helpful and found inspiration from when I was writing the talk.

	WITH table_scans as (
	SELECT relid,
	tables.idx_scan + tables.seq_scan as all_scans,
	( tables.n_tup_ins + tables.n_tup_upd + tables.n_tup_del ) as writes,
	pg_relation_size(relid) as table_size
	FROM pg_stat_user_tables as tables
	),
	all_writes as (
	SELECT sum(writes) as total_writes
	FROM table_scans

	-- Always show how long a query takes
	\timing

	-- Auto extended display mode
	\x auto

	-- Prompt db_name@host
	\set PROMPT1 '%/@%m %R%# '

	#!/bin/bash
	echo "Generating an SSL private key to sign your certificate..."
	openssl genrsa -des3 -out myssl.key 1024

	echo "Generating a Certificate Signing Request..."
	openssl req -new -key myssl.key -out myssl.csr

	echo "Removing passphrase from key (for nginx)..."
	cp myssl.key myssl.key.org
	openssl rsa -in myssl.key.org -out myssl.key

	class ProgressBar
	def initialize(units=60)
	@units = units.to_f
	end

	def print(completed, total)
	norm = 1.0 / (total / @units)
	progress = (completed * norm).ceil
	pending = @units - progress
	Kernel.print "[#{'=' * progress }#{' ' * ( pending )}] #{percentage(completed, total)}%\r"