Author Archives: Ajitesh Kumar
Hadoop Map-Reduce Explained with an Example
This article represents key steps of Hadoop Map-Reduce Jobs using a word count example. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following are the key steps of how Hadoop MapReduce works in a word count problem: Input is fed to a program, say a RecordReader, that reads data line-by-line or record-by-record. Mapping process starts which includes following steps: Combining: Combines the data (word) with its count such as 1 Partitioning: Creates one partition for each word occurence Shuffling: Move words to right partition Sorting: Sort the partition by word Last step is Reducing which comes up with …
Big Data – How Data is Retrieved and Written from/to HDFS?
This blog represents my notes on how data is read and written from/to HDFS. Please feel free to suggest if it is done otherwise. Following are steps using which clients retrieve data from HDFS: Clients ask Namenode for a file/data block Name-node returns data node information (ID) where the file/data blocks are located Client retrieves data directly from the data node. Following are steps in which data is written to HDFS: Clients ask Name-node that they want to write one or more data blocks pertaining to a file. Name-node returns data nodes information to which these data blocks needs to be written Clients write each data block to the data nodes suggested. The …
Hadoop Map-Reduce Described With Example
I came across a great page describing Hadoop map-reduce and HDFS architecture. The page presents some of the following details: HDFS responsibilities and execution flows Key characteristics of Map-Reduce lifecycle A sample example related with web crawler and Hadoop Map-reduce setup
5 Reasons Why Every Developer Must Adopt Dockers
This blog represents some of the key reasons why every developer must consider adopting for development. 1. Setup clean Dev environment within no time. Many a time, while developing, we end up changing configuration. Installing new libraries etc. With this act, the Dev environment deviates to a new state which may be different from expected QA and Production environment. With Dockers, one could rather update the image and create new containers in case new libraries need to be installed. 2. Setup Dev environment within minutes. As a matter of fact, developers could actually recreate the Dev environment every morning before starting his work. This ensures that he maintains the state …
Dockers – Top 5 Use Cases for Dockers Adoption
This blog represents top 5 use cases why IT enterprises (product & software-service vendors) should consider adopting Dockers in their SDLC. 1. Quicker Developer Onboarding into Projects: We all are aware of development environment setup related issues when taking about developers on boarding. In my recent experience, I almost spent a week to get manually setup for a recently started project comprising of just 3-4 members. I had to refer to couple of documents which was last updated few weeks back and thus was not up to date. This led to productivity loss. In my earlier experience, I saw the usage of VMs images for developer onboarding. This worked very …
ReactJS – Step-by-Step Tutorial on Quiz Development
I just finished up writing a simplistic/trivial framework using ReactJS using which one could quickly create online quizzes. The code for this could be found on github on following page named as ReactJS-Quiz. I would like to take this opportunity to share AngularJS-Quiz that I wrote sometime back. I must say that I found writing quiz framework using ReactJS more fulfilling as it got aligned to my OOP oriented thinking and I was not required to envisage templates etc as in case of AngularJS. That said, both frameworks are cool and have their own pluses and minuses. Please feel free to suggest if I missed on mentioning one or more …
ReactJS – What is this.props.items.map Property?
This article represents concepts around usage of “map” method to traverse and display list of similar objects representing a component in ReactJS. The title represents “this.props.items.map”, although it could be anything such as “this.props.profiles.map” like in examples below where profiles or items represent an array. It could be used to create a list, table etc. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following are the key points described later in this article: Map is NOT a feature of ReactJS Code Sample – Usage of “map” as in this.props.profiles.map Map is NOT a feature of ReactJS After looking …
5 Reasons Why Every Developer Must Adopt Dockers
This blog represents my thoughts on why every developer must adopt dockers for their day-to-day development purpose. I got introduced to Dockers technologies a couple of months back and trust me, I have started wondering on how I have been developing/coding prior to that. Honestly speaking, I am floored. Here are some of the top reasons why you should also give a shot to Dockers. Bring up Dev Environment in No Time One of the issue that I faced in the programming/development experience is living with same Dev environment through out the entire development cycle for months all together. At times, due to installation of software updates, the environment used …
ReactJS – How to Configure Sublime TextIDE for Faster Development
This article represents instructions on how to configure your existing Sublime Text Editor for faster development. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following are the instructions: Install the Package Control within your Sublime TextIDE. Follow instructions on package control page. Pay attention to tabs comprising of different information for Sublime Text 2 and Sublime Text 3 edition. Once done, Type ctrl+shift+p on Windows and it opens up a command palette. Type React, select ReactJS That is it! You could open up a file, save it as *.js, and type rcc. It would print class creation template …
NodeJS – How to Develop Javascript using Console (Node)
This article represents tips on how to do Javascript programming using Console with the help of NodeJS. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following are the key points described later in this article: Setting up NodeJS Environment Program Hello World & Execute on Console Setting up NodeJS Environment I recommend using Docker environment for setting up the NodeJS environment. Using that you could work on CentOS and NodeJS and make bets use of NodeJS. Follow the instructions on following page, Dummies Notes – Get Started with Docker Hello World to setup the Docker environment. Recently, Docker …
How to Migrate from Boot2Docker to Docker Toolbox
This article represents quick information on how to migrate existing Boot2Docker containers and images to newly launched Docker Toolbox, that was officially announced on this Docker’s blog. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following are the key points described later in this article: What is Docker Toolbox? Migration to Docker Toolbox What is Docker Toolbox? With the development community talking about issues related with getting up and started with Dockers and need for one-click install of Docker, Docker finally came out with something called as Docker Toolbox. This comes with following: Docker client Docker kitematic Docker …
Dummies Notes – How to Setup Oracle Data Guard
This article represents instructions which could be used to set up oracle data guard on a primary and one or more physical standby database. The article presumes that you have a basic understanding of what is Oracle Data guard and why it needs to be set up. Following are key aspects which are discussed later in this article: Primary Database Setup Physical Standby Database Setup Following is details on primary and physical standby database setup: Primary Database Setup: Configure the primary database appropriately including doing some of the following: Enable force logging Alter the database parameters such as following. This is one time activity and does not needed to be …
Docker – How to Install NodeJS on Docker
This article represents quick instructions on how to install NodeJS on CentOS Docker Image. The detailed instructions of installing NodeJS on linux could be found on this page. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following is the set of instructions: Install the docker on your machine. Pull the Centos docker image Create a container using the Centos docker image. Following command could be used: docker run -ti -dP –name centos -v /c/Users:/mnt/Users centos:latest /bin/bash Start the docker container and attach. Following command can be used: # Starts the docker container docker start centos # Attach docker …
RPM – How to Build RPM Package
This article represents tips to build RPM package using rpmbuild command. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following are the key points described later in this article: Install RPMBuild Package Instructions to Create RPMs Install RPMBuild Package Make sure that rpmbuild exists. Type rpmbuild in command line and confirm that usage text appears. In case, rpmbuild does not exists, download it using command, “yum -y install rpm-build” Instructions to Create RPMs Create a top level folder such as “rpmbuild” within home directory. Go to rpmbuild folder using command such as “cd rpmbuild” Create following folder within …
Docker – How to Install NodeJS on Docker
This article represents quick instructions on how to install NodeJS on CentOS Docker Image. The detailed instructions of installing NodeJS on linux could be found on this page. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. Following is the set of instructions: Install the docker on your machine. Pull the Centos docker image Create a container using the Centos docker image. Following command could be used: docker run -ti -dP –name centos -v /c/Users:/mnt/Users centos:latest /bin/bash Start the docker container and attach. Following command can be used: # Starts the docker container docker start centos # Attach docker …
ReactJS – Controlled Component Code Example
This article represents code sample for ReactJS UI controlled components along with related details. Please feel free to comment/suggest if I missed to mention one or more important points. Also, sorry for the typos. The code sample represents an input field consisting of “Calvin”. Once you change the text, the “calvin” written with “Hello” would also change. Following are the key points described later in this article: What are controlled components? Code Example – Controlled Component What are Controlled Component? As per the ReactJS Form page, An <input> with “value” set is a controlled component. In a controlled <input>, the value of the rendered element will always reflect the value …
I found it very helpful. However the differences are not too understandable for me