Welcome!

Open Source Cloud Authors: Yeshim Deniz, Pat Romanski, Elizabeth White, Liz McMillan, Zakia Bouachraoui

Related Topics: @DXWorldExpo, Java IoT, Open Source Cloud, @CloudExpo, Apache, SDN Journal

@DXWorldExpo: Article

The Components of Apache Hadoop

A technical description of the projects that comprise Hadoop

What is Hadoop?
Following my high-level write-up of Hadoop and Big Data, this article will present each of the components or projects that make up Hadoop with a technical description of each.

First, what is Hadoop?

Hadoop stores and processes large volumes of a wide variety of data that changes rapidly. It analyses and summarizes the data. For example: census of a city, web page analytics, threat analysis, risk models, network failures, etc.

Hadoop is redundant and reliable, powerful and focused on batch processing.

Hadoop divides a large data processing job into many smaller tasks that can be distributed across all the nodes

Hadoop comprises two main components:

  • MapReduce: The task to analyse the data and summarize the results
  • HDFS: The distributed file system, on commodity server hardware, that contains the data.

On each server there is a task tracker and a data node:

DataNode
The data node stores the data in HDFS and keeps track of access to the data.

TaskTracker
Task tracker launches a map reduce job on a node and manages the many tasks within one MapReduce job. So if my project was to conduct a census count, task tracker may count the members of a household on a data node. When finshed, task tracker reports its status to the job tracker. (Note: as of this writing, May 2013, TaskTracker is being obsoleted and replaced by "Yarn" in MapReduce v2.

JobTracker
Job tracker keeps track of all the jobs being executed and tries to schedule each map job as close to the actual data being processed. If a task has failed or disappeared perhaps due to hardware failure, job tracker will assign that task to another node.

So, now that I know what is a task and job how do I write tasks? How does a user create a map reduce job? There are various projects that make it easy. (As to how the projects were named, don't ask me!)

Apache Pig
To write a computer program, a software engineer might use a compiler, like "C",  that compiles 'pseudo english instructions (IF, THEN, FOR, ELSE) and creates machine code that a computer an execute. Similarly, Apache Pig is a high level language that expresses data map reduce jobs and translates them to JAVA computer language. Pig's primary feature is that it can be run in parallel, meaning many map reduce jobs can run simultaneously to allow linear scaling and efficiency.

Apache Hive
Hive is a SQL like language, HiveQL, which allows you to define computation in SQL like language and then and translate it down into map reduce JAVA code. Hive also allows traditional MapRedce programmers to plug in their custom MapReducers when it is  inefficient to express their logic in HiveQL.

hBase
hBase is a simple interface to distributed data that allows incremental processing. hBase stores its information in HDFS and metadata in zookeeper.

hCatalog
hCatalog is an abstraction layer for referencing data without using the underlying file­names or formats. It insulates users and scripts from how and where the data is physically stored.

Some of the smaller projects

Mahout
Mahout is a machine learning library to write MapReduce applications focused on machine learning

Ambari, Gagli and Nagios
These projects help you understand what goes on in your cluster

Scoop
Scoop is a tool that lets you run map reduce applications to or from sql databases

Oozie
Oozie is a workflow that triggers MapReduce jobs and executes them automatically or launches when new data becomes available.

Flume
Streams inputs into hadoop and gets that data loaded into hdfs

Here is a graphical view of the components

Hadoop components, courtesy of Hortonworks

(courtesy of Hortonworks)

More Stories By Jonathan Gershater

Jonathan Gershater has lived and worked in Silicon Valley since 1996, primarily doing system and sales engineering specializing in: Web Applications, Identity and Security. At Red Hat, he provides Technical Marketing for Virtualization and Cloud. Prior to joining Red Hat, Jonathan worked at 3Com, Entrust (by acquisition) two startups, Sun Microsystems and Trend Micro.

(The views expressed in this blog are entirely mine and do not represent my employer - Jonathan).

IoT & Smart Cities Stories
Early Bird Registration Discount Expires on August 31, 2018 Conference Registration Link ▸ HERE. Pick from all 200 sessions in all 10 tracks, plus 22 Keynotes & General Sessions! Lunch is served two days. EXPIRES AUGUST 31, 2018. Ticket prices: ($1,295-Aug 31) ($1,495-Oct 31) ($1,995-Nov 12) ($2,500-Walk-in)
Andrew Keys is Co-Founder of ConsenSys Enterprise. He comes to ConsenSys Enterprise with capital markets, technology and entrepreneurial experience. Previously, he worked for UBS investment bank in equities analysis. Later, he was responsible for the creation and distribution of life settlement products to hedge funds and investment banks. After, he co-founded a revenue cycle management company where he learned about Bitcoin and eventually Ethereal. Andrew's role at ConsenSys Enterprise is a mul...
Nicolas Fierro is CEO of MIMIR Blockchain Solutions. He is a programmer, technologist, and operations dev who has worked with Ethereum and blockchain since 2014. His knowledge in blockchain dates to when he performed dev ops services to the Ethereum Foundation as one the privileged few developers to work with the original core team in Switzerland.
René Bostic is the Technical VP of the IBM Cloud Unit in North America. Enjoying her career with IBM during the modern millennial technological era, she is an expert in cloud computing, DevOps and emerging cloud technologies such as Blockchain. Her strengths and core competencies include a proven record of accomplishments in consensus building at all levels to assess, plan, and implement enterprise and cloud computing solutions. René is a member of the Society of Women Engineers (SWE) and a m...
Digital Transformation and Disruption, Amazon Style - What You Can Learn. Chris Kocher is a co-founder of Grey Heron, a management and strategic marketing consulting firm. He has 25+ years in both strategic and hands-on operating experience helping executives and investors build revenues and shareholder value. He has consulted with over 130 companies on innovating with new business models, product strategies and monetization. Chris has held management positions at HP and Symantec in addition to ...
The challenges of aggregating data from consumer-oriented devices, such as wearable technologies and smart thermostats, are fairly well-understood. However, there are a new set of challenges for IoT devices that generate megabytes or gigabytes of data per second. Certainly, the infrastructure will have to change, as those volumes of data will likely overwhelm the available bandwidth for aggregating the data into a central repository. Ochandarena discusses a whole new way to think about your next...
CloudEXPO | DevOpsSUMMIT | DXWorldEXPO are the world's most influential, independent events where Cloud Computing was coined and where technology buyers and vendors meet to experience and discuss the big picture of Digital Transformation and all of the strategies, tactics, and tools they need to realize their goals. Sponsors of DXWorldEXPO | CloudEXPO benefit from unmatched branding, profile building and lead generation opportunities.
Dynatrace is an application performance management software company with products for the information technology departments and digital business owners of medium and large businesses. Building the Future of Monitoring with Artificial Intelligence. Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more busine...
All in Mobile is a place where we continually maximize their impact by fostering understanding, empathy, insights, creativity and joy. They believe that a truly useful and desirable mobile app doesn't need the brightest idea or the most advanced technology. A great product begins with understanding people. It's easy to think that customers will love your app, but can you justify it? They make sure your final app is something that users truly want and need. The only way to do this is by ...
DXWorldEXPO LLC announced today that Big Data Federation to Exhibit at the 22nd International CloudEXPO, colocated with DevOpsSUMMIT and DXWorldEXPO, November 12-13, 2018 in New York City. Big Data Federation, Inc. develops and applies artificial intelligence to predict financial and economic events that matter. The company uncovers patterns and precise drivers of performance and outcomes with the aid of machine-learning algorithms, big data, and fundamental analysis. Their products are deployed...