How to install EPEL Repository on RHEL/CentOS 7.x/6.x/5.x

This is "How To" guide to show us, how one can configure RHEL/CentOS system to use Extra Packages from EPEL repository. After enabling the EPEL repository, one can easily install standard open source packages and their dependencies by using YUM command.  

In this article, we would discuss below points:
What is EPEL?
Why one should use EPEL repository?
How To enable EPEL repository on RHEL/CentOS 7/6/5?
How To verify if EPEL repository is enabled or not?
How To use EPEL repository?

Is Tomcat a web server or an application server?

Tomcat is a web server (handles HTTP requests/responses) and web container (implements Java Servlet, JavaServer Pages, Java Expression Language and Java WebSocket technologies) if we don't consider that we have all the add-ons and plugins made available through open source or commercially with Tomcat. Tomcat doesn't implement the complete Java EE API and doesn't have EJB container. Although we could run some applications in Tomcat(one could easily argue that it is an application server) it will not be considered as a full-fledged application server as it lacks some features of the application server.

Conclusion:
One could develop many applications on top of Tomcat with pluggable services and add-ons. If Tomcat + add-ons + pluggable services then we can call it an Application Server.

Thank you for reading this article. Hope you would like it. If you have any suggestion or have any question do let me know in the comment box. Happy Learning!!😌

Why Checked Exception exists in Java when we have Runtime Exception in our bucket?

Have you ever thought Why Checked Exception exists in Java when we have Runtime Exception to convey exceptional cases in our program? There must be a pretty good reason behind it? Have you ever tried to find it out?

Today we would provide you a small overview about Checked Exception then we directly jump on answering our topic of interest today i.e. Why Checked Exception exists in Java?

How to Fix the FeedBurner Email Subcription Error: The publisher has deactivated subscriptions by email

Have you came across below error while trying to subscribe any website or blog using your email address:
 

The errors state that : The publisher has deactivated subscriptions by email and  The feed does not have subscriptions by email enabled.

These error messages tells us two thing about the website or a blog which we are trying to subscribe:

• The website or blog is using Google's free service i.e. FeedBurner service for their web feed management (i.e. feed subscription)
• The owner of the website or a blog previously allowed feed subscription by email but now  they have deactivated this service

In this article, I would show you the steps with screenshots to fix the above FeedBurner Email Subscription Error.

Introducing Vagrant

Have you ever faced or heard about below problems:

• Environment setup on multiple systems whether it is development, staging or QA which includes multiple server setup, software and database installation as well as their configuration. We all agree on one point that traditional way of Environment setup is very time consuming and effort taking.
• The process/scripts for setting up the server / database / software that worked in one system are now failing in another. I am referring to “it does not work on my machine” excuse that developers used to raise for any kind of issues. :-)
• New member joins the team - you have to again setup the same development environment; you have to recall the complete setup process. Even if you are happy and ready to set up the development environment in traditional way, if it is not properly documented and you miss a minor thing then boom...red flag!  
• Unable to replicate the issues in your local development environment that's happening in production or in other team members workstation

If yes, then this article/tutorial is a must for you. Vagrant addresses these problems and helps us to create and manage portable, reproducible development environment. If you haven’t faced or heard about above problems or Vagrant, then this is the right time to get acquainted to it. Vagrant is very popular open source project.

In this article, we would discuss:
What is Vagrant?
Why do we need Vagrant?
What are the main features offered by Vagrant?

VirtualBox Overview

Have you ever faced problem in understanding or confused about the terms like VirtualBox ,Virtual Machine. If yes, then this article would clarify all your doubts. Today we would discuss below topics:

What is VirtualBox?
Why one should use VirtualBox?

How to Add Hreflang Language Tag in Blogger Blog

Have you came across above error in Google Search Console while tracking your site's search performance?

Hreflang Attribute

Hello Friends, Have you ever wondered:

• How does Google or any other search engine identify the language of any blog or website?
• How does the users get tailored search results (language and region specific website URLs) based on their language and region?

The answer to all these question is : hreflang

In this article, we would discuss:

What is hreflang?
When should we use the hreflang?
What’s the SEO benefit of using hreflang?
How does we implement hreflang?
hreflang tag examples on Facebook