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Adding 2 nodes to an existing 3-node ZooKeeper ensemble without losing the Quorum

Since many deployments may start out with 3 nodes and so little is known about how to grow a cluster from 3 memebrs to 5 members without losing the existing Quorum, here is an example of how this might be achieved.

In this example, all 5 nodes will be running on the same Vagrant host for the purpose of illustration, running on distinct configurations (ports and data directories) without the actual load of clients.

YMMV. Caveat usufructuarius.

Step 1: Have a healthy 3-node ensemble

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#!/bin/bash

NUMCPUS=`grep -c processor /proc/cpuinfo`

if [ -z "$1" ] ; then
      NUMINSTANCES=2
else
      echo $1 | grep "^[0-9]*$" >/dev/null
      if [ "$?" -ne 0 ] ; then
            echo Argument $1 is not a number. Aborting.

purbon

import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import java.io.*;

/** Establish a SSL connection to a host and port, writes a byte and
 * prints the response. See
 * http://confluence.atlassian.com/display/JIRA/Connecting+to+SSL+services
 */
public class SSLPoke {
    public static void main(String[] args) {

purbon

import java.math.BigInteger;
import java.security.PublicKey;
import java.security.PrivateKey;
import java.security.KeyFactory;
import java.security.Security;
import java.security.KeyPairGenerator;
import java.security.KeyPair;
import java.security.SecureRandom;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.ECGenParameterSpec;

purbon

YARD CHEATSHEET http://yardoc.org

cribbed from http://pastebin.com/xgzeAmBn

Templates to remind you of the options and formatting for the different types of objects you might want to document using YARD.

Modules

Namespace for classes and modules that handle serving documentation over HTTP

purbon

#!/bin/bash

ES_URL='https://download.elasticsearch.org/elasticsearch/elasticsearch/elasticsearch-1.4.1.tar.gz'
ES_HOME='/tmp/es'
DATA_DIR_ES='/tmp/es/data'
ES_PID=$ES_HOME/es.pid

update_config ()
{
  config="cluster.name: temp-tal-elasticsearch

purbon

1. General Background and Overview

• Probabilistic Data Structures for Web Analytics and Data Mining : A great overview of the space of probabilistic data structures and how they are used in approximation algorithm implementation.
• Models and Issues in Data Stream Systems
• Philippe Flajolet’s contribution to streaming algorithms : A presentation by Jérémie Lumbroso that visits some of the hostorical perspectives and how it all began with Flajolet
• Approximate Frequency Counts over Data Streams by Gurmeet Singh Manku & Rajeev Motwani : One of the early papers on the subject.
• [Methods for Finding Frequent Items in Data Streams](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.187.9800&rep

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/**
 * Read the value of a header in the current document.
 *
 * This uses a [single] XMLHTTPRequest to do a HEAD of the current document 
 * and fetch HTTP response header values. Note that the implementation is 
 * rather stupid in that it spins waiting for the XMLHTTPRequest to complete
 * if it hasn't been called yet.
 *
 * @param name string

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{
	"name": "streamingtest",
	"version": "0.0.1",
	"engines": {
		"node": ">=0.6.0"
	},
	"dependencies": {
		"express": "2.5.x",
		"coffee-script": "1.2.x"
	},

purbon

In the spirit of Railsgirls Berlin, we want to start a programming education group for JavaScript. We need your help to get all the coaching done.

If you are interested in coaching JavaScript, fork this gist and add yourself or leave your contact data in a comment:

• Jan Lehnardt jan@apache.org / @janl
• Misha Reyzlin hello@mishareyzlin.com / @gryzzly
• Johannes Emerich johannes@emerich.de / @knuton
• Mathias Schäfer / @molily