Aravind Yarram yaravind

Introduction to Kafka

Kafka acts as a kind of write-ahead log (WAL) that records messages to a persistent store (disk) and allows subscribers to read and apply these changes to their own stores in a system appropriate time-frame.

Terminology:

Producers send messages to brokers
Consumers read messages from brokers
Messages are sent to a topic

Hypermedia API design session

Proposed/ran by Andreas Schmidt, Nokia

Based off his design around the Nokia Places API

Notes

Picked JSON, no support for XML
Added ?accept=application/json to the URL in the browser for a raw response

Setting up github and bitbucket on the same computer (Windows)

Guide for Windows

mix3d asked for some help using this guide with windows so here we go. This was tested with Windows 10. Run all commands in Git Bash once it's installed.

Github will be the main account and bitbucket the secondary.

Git for Windows

Download and install Git for Windows
- In the installer, select everything but decide if you want a desktop icon (2nd step)

Both command sourcing (CS) and event sourcing (ES) rely on determinism for correctness.

The correctness condition for ES is the determinism (purity) of the function State -> Event -> State. Given that this function is deterministic, aka it always maps the same inputs to the same ouputs, we can rely on it to reconstitute state at any point in time. Determinism is typically achieved by ensuring that the Event has all required information to make the state transition, ie no side effects. The Event then is a sort of "closure" of all pertinent information about the event.

The correctness condition for CS is the determinism of the function State -> Command -> Event. Herein lies one of the distinctions between command sourcing and event sourcing - a program can control its output, but it not its input. Since one can't control the input, aka command, one can't in general, enrich it with all required information to make the above function deterministic. A consequence of this is that you can't simply replay a

Whether you're trying to give back to the open source community or collaborating on your own projects, knowing how to properly fork and generate pull requests is essential. Unfortunately, it's quite easy to make mistakes or not know what you should do when you're initially learning the process. I know that I certainly had considerable initial trouble with it, and I found a lot of the information on GitHub and around the internet to be rather piecemeal and incomplete - part of the process described here, another there, common hangups in a different place, and so on.

In an attempt to coallate this information for myself and others, this short tutorial is what I've found to be fairly standard procedure for creating a fork, doing your work, issuing a pull request, and merging that pull request back into the original project.

Creating a Fork

Just head over to the GitHub page and click the "Fork" button. It's just that simple. Once you've done that, you can use your favorite git client to clone your repo or j

#The Functional Programmers Cheat Sheet for NDC Oslo 2014

This year NDC Oslo has a full three-day functional programming track with an amazing lineup. If you agree that the future of programming is FP, use this as your "auto pilot" guide on what sessions to attend.

Cheer for sessions on Twitter using the #ndcoslo and #fptrack hashtags.

[The full agenda (including non-fp sessions) is here].

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

	#!/bin/sh

	# script to automate the load and export to CSV of an oracle dump
	# This script assumes:
	# * you have the vagrant published key available locally in your .ssh directory
	# * You have the Oracle VirtualBox image running locally
	# ** ssh port-forwarding is configured for host port 2022 -> guess port 22.

	set -e

	package funsets

	import org.scalatest.FunSuite

	import org.junit.runner.RunWith
	import org.scalatest.junit.JUnitRunner

	/**
	* This class is a test suite for the methods in object FunSets. To run
	* the test suite, you can either:

	import scala.collection.mutable.Map

	import org.apache.spark.{Accumulator, AccumulatorParam, SparkContext}
	import org.apache.spark.scheduler.{SparkListenerStageCompleted, SparkListener}
	import org.apache.spark.SparkContext._


	/**
	* just print out the values for all accumulators from the stage.
	* you will only get updates from named accumulators, though