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Avoid where in a reduce clause

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:30
We got a customer question about a map/reduce index that produced the wrong results. The problem was a problem between the conceptual model and the actual model of how Map/Reduce actually works. Let us take the following silly example. We want to find all the animal owner’s that have more than a single animal. We define an index like so: Preview Text:  ...
Categories: Java

Scrum and Quantum Physics

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:30
This article was originally written by Brett Goldman at the Axosoft blog.  Preview Text:  Since Scrum is an iterative process, you can have great success by focusing on things that you can say with a fair degree of confidence, while still allowing for some uncertainty in all planning and estimates. Legacy ...
Categories: Java

Pi Tracker–Code Running in Raspberry Pi

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:30
In my last post you can see the Tracker in action. This post I will explain the code running in Raspberry pi that controls the Tracker. I use Wiring Pi to control the  GPIO instead of the default RPI.GPIO. The intention of using Wiring pi is because Software PWM is easy to implement. Any way after the first run of the tracker I realized that my tracker is slow moving one and no need to...
Categories: Java

Part 1: Getting Started with Ansible

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:30
An introduction to Ansible Configuration Management A brief history of Configuration Management =========================================== * CFEngine - Released 1993. Written in C * Puppet - Released 2005 - Written in Ruby. Domain Specific Language (DSL. SSL Nightmare. * Chef - Released 2009 - Written in Ruby, also a DSL, more like pure Ruby * Juju - Released 2010, Python, Very ubuntu. * Salt...
Categories: Java

Why You Should Build an Immutable Infrastructure

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:30
Some of the major challenges today when building infrastructure are predictability, scalability and automated recovery. A predictable system will promote the exact same artifact that you tested into your production system so no intermittent failure can cause any trouble. A scalable system make it trivial, especially automatically, to deal with any rise in traffic. Preview Text:  ...
Categories: Java

Redis Commands Visualized: One Good-Lookin' Database

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:30
For no particular reason at all, Redis Labs' Itamar Haber took a D3.js swing at the bulk of Redis' 160-ish commands, creating an interactive visualization of the lot of them - in Redis colors, of course. According to Haber, it's set up like this: Preview Text:  For no particular reason at all, Redis Labs' Itamar Haber took a D3.js swing at the...
Categories: Java

Null Object Pattern Implementation in Groovy

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:30
Simple real life problem. The proper service implementation is taken from a map based on a given service key. For an unknown/unsupported key a meaningful exception should be thrown. How could it be implemented without an if statement? Business context. PriceProvider allows to get price for the requested product. A concrete implementation call proper provider via Web Service (REST or SOAP). There...
Categories: Java

What's New in Oracle SOA Suite 12c?

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:15
Introduction With the recent release of SOA Suite 12c, it seems appropriate to give a quick rundown of some of the new features and improvements made to it from the last release. For those of you who don’t know, SOA Suite is a software collection (or suite, if you prefer) that can be used together to realise a Service-Oriented Architecture. What’s New? Preview Text:  ...
Categories: Java

VelocityEngine Spring Java Config

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:00
This is a first post in a series of short code snippets that will present the configuration of Spring beans from XML to Java.XML: <bean id="velocityEngine" class="org.springframework.ui.velocity.VelocityEngineFactoryBean"> <property name="velocityProperties"> <value> resource.loader=class ...
Categories: Java

A Schema Change Inconsistency with Galera Cluster for MySQL

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:00
Originally written by Stephane Combaudon I recently worked on a case where one node of a Galera cluster had its schema desynchronized with the other nodes. And that was although Total Order Isolation method was in effect to perform the schema changes. Let’s see what happened.BackgroundFor those of you who are not familiar with how Galera can perform schema changes, here is a short recap: ...
Categories: Java

Neo4j: LOAD CSV - Processing Hidden Arrays in Your CSV Documents

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:00
I was recently asked how to process an ‘array’ of values inside a column in a CSV file using Neo4j’s LOAD CSV tool and although I initially thought this wouldn’t be possible as every cell is treated as a String, Michael showed me a way of working around this which I thought was pretty neat. Let’s say we have a CSV file representing people and their friends. It might look like this: ...
Categories: Java

Creating a Simple Cluster with GlassFish

Javalobby Syndicated Feed - Tue, 22-Jul-14 22:00
In this post, I’ll go through the first steps of getting Glassfish installed and clustered with Apache to proxy requests. All this will be set up using one CentOS and one Fedora instance, but the steps should require little to no tweaking for other Linux platforms. Installing Glassfish Preview Text:  In this post, I’ll go through the first...
Categories: Java

Keeping Things DRY: Method Overloading

Javalobby Syndicated Feed - Mon, 21-Jul-14 23:00
A good clean application design requires discipline in keeping things DRY:Everything has to be done once.Having to do it twice is a coincidence.Having to do it three times is a pattern.— An unknown wise manNow, if you’re following the Xtreme Programming rules, you know what needs to be done, when you encounter a pattern: Preview Text:  A...
Categories: Java

Time - memory tradeoff with the example of Java Maps

Javalobby Syndicated Feed - Mon, 21-Jul-14 23:00
This article illustrates the general time - memory tradeoff with the example of different hash table implementations in Java. The more memory a hash table takes, the faster each operation (e. g. getting a value by key or putting an entry) is performed. Benchmarking method Hash maps with int keys and int values were tested. Memory measure is relative usage over theoretical minimum. For example,...
Categories: Java

What's to Come in Oracle Big Data SQL

Javalobby Syndicated Feed - Mon, 21-Jul-14 23:00
We heard some interesting news regarding SQL and Big Data earlier this month, and now there's more: Oracle Big Data SQL. Even if that incredibly creative name doesn't do it for you, it looks like it should be useful as a way to connect the various Big Data technologies you might be working with. Preview Text:  We heard some interesting news...
Categories: Java

Four Point DevOps Story

Javalobby Syndicated Feed - Mon, 21-Jul-14 23:00
Build team interest and passion in DevOps by promoting four DevOps themes: Preview Text:  What solution or best practices do you see solving balkanized, silo development tooling, fractured governance, disconnected workflow, and incomplete status reporting when working with distributed outsourced teams or across internal teams? ...
Categories: Java

Highly Available PHP sessions using memcached 4 Coherence

Javalobby Syndicated Feed - Mon, 21-Jul-14 22:35
In this blog we will show you step-by-step how to use PHP memcached support, combined with our new library to store PHP sessions directly in Oracle Coherence using the memcached protocol. Preview Text:  In this blog we will show you step-by-step how to use PHP memcached support, combined with our new library to store PHP sessions directly in Oracle...
Categories: Java

Test Attribute #4 - Accuracy

Javalobby Syndicated Feed - Mon, 21-Jul-14 22:35
Preview Text:  Accuracy helps us fix problems quickly. But it’s definitely not so easy to come by, because it depends very much on the tested code. However, using the combination of the methods I suggested, and making use of working to test to refactor and simplifications, test accuracy is definitely within reach. Legacy ...
Categories: Java

Terminal Connection to the RIoT Board

Javalobby Syndicated Feed - Mon, 21-Jul-14 22:35
I admit: I love command line interfaces. Because that gives me usually much more control than any GUI (Graphical User Interface). I like the fact that they have put a UART interface on the RIoT board: Preview Text:  The RIoT board comes with a 3-pin header (Tx, Rx and GND) which gives a console/UART connection to the board. Any kind of...
Categories: Java

Hibernate Hidden Gem: The Pooled-Lo Optimizer

Javalobby Syndicated Feed - Mon, 21-Jul-14 22:30
In this post we’ll uncover a sequence identifier generator combining identifier assignment efficiency and interoperability with other external systems (concurrently accessing the underlying database system).Traditionally there have been two sequence identifier strategies to choose from. Preview Text:  In this post we’ll uncover a sequence...
Categories: Java

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