Tim Kellogg tkellogg

I already have a ring of servers (message brokers, to be precise) that uses Cassandra to persist data needed to recover from a crash. We played with some configurations and realized that we get much better performance if we run Cassandra on the same box as the app. The row key is well distributed, so 1/n chance that the IO operation can be performed locally. The traffic is also well distributed (it's a safe assumption) so the question is, why rely on the row key to distribute the rows around the ring? Why can't I just assume the local shard is the master that I want to write to? This would give me a 100% chance that the IO operation can be performed locally.

I assume this is a bit of a corner case, so there's probably nothing pre-boxed for my situation. But is there something that would function as a good starting point?

As for statements equating MQTT with CoAP style REST and why they're not complete or true:

Statement 1

CoAP URI path == MQTT topic

This appears to be true because they have a lot in common. In reality an MQTT topic is ephemeral (or you could say it's just a convention). You don't create it, you don't delete it, you just use it to synchronize where you're publishing and where you're subscribing.

A CoAP URI is material. Or at least it is with Californium, and I believe it has to be this way as long as CoAP is used in conjunction with CoRE link formats because all resources have to be enumerated so they can be described by the CoRE document.

	class Anon1
	{
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	}

	# Add this line to your software sources
	deb http://debian.meebey.net/experimental/mono /

	sudo apt-get update
	# of course, apt-get remove mono-complete first...
	sudo apt-get install mono-complete

	# I installed monodevelop from apt just to get all the prereqs
	sudo apt-get install monodevelop

	<!DOCTYPE html>
	<meta charset="utf-8">
	<link rel="stylesheet" href="http://cmx.io/v/0.1/cmx.css">
	<script src="http://cmx.io/v/0.1/cmx.js" charset="utf-8"></script>
	<style>.cmx-user-scene4 .cmx-text-border .cmx-path {stroke: orange}</style>
	<body>
	<div style="max-width:900px; -webkit-transform:rotate(0deg)">

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	def bar(value: Int) = foo(Some(value / 3))

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	case Some(v) => Some(v)
	case None => None
	}

	#!/bin/sh

	msg=$(git log -n 1 --format="%B")
	git reset HEAD^
	git add -A
	git commit -m "$msg"

	object People {
	implicit val columnFamily: ColumnFamily = getColumnFamily

	def getPersonByName(name: String)(implicit cf: ColumnFamily) = ...
	}

	class ProdUsage {
	// uses ColumnFamily from object People
	def foo = People.getPersonByName("Jordan")
	}

	case class Fail(text: Option[String])

	object Main extends App {
	import org.json4s._
	import org.json4s.native.Serialization
	import org.json4s.native.Serialization.{read, write}
	implicit val formats = org.json4s.DefaultFormats

	read[Fail]("""{"notext":"foo"}""").text match {
	case Some(txt) => // ClassCastException here when using json4s v3.1.0

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	sealed trait ValueNode extends ParseTree
	sealed trait PrimitiveValueNode extends ValueNode

	case class OrNode(left: ParseTree, right: ParseTree) extends ParseTree
	case class AndNode(left: ParseTree, right: ParseTree) extends ParseTree
	case class BoolNode(value: Boolean) extends PrimitiveValueNode
	case class IntNode(value: Int) extends PrimitiveValueNode
	case class StringNode(value: String) extends PrimitiveValueNode
	// Use refined trait ValueNode to better describe what value can actually hold