Naveen Sidda softwarecoolie

Rough Notes about CQRS and ES

Once upon a time…

I once took notes (almost sentence by sentence with not much editing) about the architectural design concepts - Command and Query Responsibility Segregation (CQRS) and Event Sourcing (ES) - from a presentation of Greg Young and published it as a gist (with the times when a given sentence was heard).

I then found other summaries of the talk and the gist has since been growing up. See the revisions to know the changes and where they came from (aka the sources).

It seems inevitable to throw Domain Driven Design (DDD) in to the mix.

Example Git Branching Diagram

You can use this diagram as a template to create your own git branching diagrams. Here's how:

Create a new diagram with diagrams.net (formerly draw.io)
Go to File > Open From > URL
Insert this url (it points to the xml data below): https://gist.githubusercontent.com/bryanbraun/8c93e154a93a08794291df1fcdce6918/raw/bf563eb36c3623bb9e7e1faae349c5da802f9fed/template-data.xml
Customize as needed for your team.

	# 0 is too far from ` ;)
	set -g base-index 1

	# Automatically set window title
	set-window-option -g automatic-rename on
	set-option -g set-titles on

	#set -g default-terminal screen-256color
	set -g status-keys vi
	set -g history-limit 10000

	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

	#!/bin/bash

	VENDORID=80012345
	DATAFOLDER="${HOME}/Sales Reports"
	CLASSPATH="${HOME}/bin"

	ZVENDORID=`printf %.10d ${VENDORID}`

	for i in 1 2 3 4 5 6 7 8 9 10 11 12; do
	for REGION in "AE" "AU" "CA" "CH" "CN" "DK" "EU" "GB" "HK" "ID" "IL" "IN" "JP" "MX" "NO" "NZ" "RU" "SA" "SE" "SG" "TR" "TW" "US" "WW" "ZA" ; do

	Add-Type -AssemblyName System.Windows.Forms

	while ($true)
	{
	$Pos = [System.Windows.Forms.Cursor]::Position
	$x = ($pos.X % 500) + 1
	$y = ($pos.Y % 500) + 1
	[System.Windows.Forms.Cursor]::Position = New-Object System.Drawing.Point($x, $y)
	Start-Sleep -Seconds 10
	}

	package main

	import (
	"fmt"
	"os"
	"os/exec"
	"syscall"
	)

	func main() {

	/*
	Parallel processing with ordered output in Go
	(you can use this pattern by importing https://github.com/MarianoGappa/parseq)

	This example implementation is useful when the following 3 conditions are true:
	1) the rate of input is higher than the rate of output on the system (i.e. it queues up)
	2) the processing of input can be parallelised, and overall throughput increases by doing so
	3) the order of output of the system needs to respect order of input

	- if 1 is false, KISS!

	import re
	import json

	# save the positive words into a list called p_list
	with open('positive.txt') as f:
	p_txt = f.read()
	p_txt = re.sub('[,\.()":;!@#$%^&*\d]\|\'s\|\'', '', p_txt)
	p_list = p_txt.replace('\n',' ').replace(' ',' ').lower().split(' ')
	# test if cool is in the list
	print 'cool is in the postive list: ', 'cool' in p_list

	---
	version: '3'
	services:
	zookeeper:
	image: confluentinc/cp-zookeeper:7.1.1
	platform: linux/amd64
	hostname: zookeeper
	container_name: zookeeper
	ports:
	- "2181:2181"