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In this tutorial, we will be learning what is Hazelcast and when to use it. Hazelcast IMDG is an open-source in-memory data grid based on Java. It is a clustered data-grid, backed by physical or virtual machines. In this tutorial, we will be looking at Hazelcast basic, in the next tutorial we will be implementing Spring Boot + Hazelcast application.

What is Hazelcast?

Let us take an example of a simple Banking Application that performs CRUD operations for User Bank Accounts. Initially, we develop this application using a monolithic approach. The banking application will be deployed into a single server with the JVM running. And the bank details will be saved in the Database. …


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In this tutorial, we are going to learn about Kubernetes from the beginning. Kubernetes is the Greek word for helmsman or captain of a ship. You can get an idea from the logo also.

Kubernetes is also referred to as K8s, and that is because there are 8 characters between K and S.

In this session, I am planning to go very beginning and step by step. This will be very easy and very interesting. So let’s get started.

In this tutorial, I am going to explain to you about,

  • What is Kubernetes
  • What is a Container Orchestration Engine
  • Why do we need Kubernetes? …


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In this tutorial, we are discussing the Whatsapp Application Design. Whatsapp is a chat-based application. Once you know the design of Whatsapp application you would design any chat-based application with newer features.

The special things about Whatsapp are,

  • One to one Chat — You can make a chat with your friends or any numbers which you have in your contacts.
  • Group Messaging — Whatsapp has Groups. Almost 200 people can enter to one group.
  • Sent + Delivered + Read receipts — Here you can see tick marks coming in based on what stage is the message on.
  • Online / Last Seen — The person is online or the person last online…


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In this tutorial, we are going to learn about Load Balancing. This is an important thing that you need to know when you are building systems. Let me get a simple example for explaining the concept of Load Balancing.

If you have a single computer that is running a program(algorithm) and someone comes to you and says I will pay you money just let me use your algorithm.

And assume that there is a person with a mobile phone. He can connect to your machine and use the algorithm. He only uses your algorithm and gets the result. And every time he does that he pays you some money. But keep the money, marketing, and other things aside. We have technical specifications. This algorithm needs to run. …


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In the previous article, we learned how to create Users + Manage + Assign Roles in Jenkins. In this article, I will be highlighting how can we create some basic JOBS in Jenkins. Furthermore, these are the points which I am going to explain.

  • How to create a basic Job in Jenkins.
  • Basic Job Configurations.
  • How to run the Job remotely.
  • How to chain Job Execution

How to create a basic Job in Jenkins?

First of all click on New Item on the Jenkins Dashboard. Then Give a name to your project. Then you can select a Freestyle or Multi-configuration project. For this tutorial please go with the Freestyle project. …


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In this tutorial, we are going to learn How to do simple configurations for Jenkins. Here are the points which I am going to explain in this tutorial.

  • How to create new Users?
  • How to configure Users?
  • How to create new Roles?
  • How to assign users to Roles?
  • How to control user access on Projects?

First of all, make sure whether your Jenkins server is up and running. Please go through my previous tutorial for getting up and running the Jenkins server.

Once you run the Jenkins server it will start on default 8080 port. …


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This will be a tutorial series of Jenkins and we will start from the very basics of Jenkins and go to the deep points. First, we will discuss What is Jenkins and How to use it. Then later on we will discuss Jobs in Jenkins and the plugins that we can use for Jenkins and so on. Later we will discuss how to do continuous integration with Jenkins.

Lets Start!

What is Jenkins and Why we use it?

Jenkins is a Java application. Because it is a Java application it is platform-independent and it does not require any specific platform. You do not have to worry about the operating system that you are using. Jenkins uses for continuous integration and continuous delivery. …


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In this tutorial, we will be learning about SonarQube. It is a Software testing tool used to improve the quality of the code and help fix errors very early in the development. In the previous tutorial, I explained about What Software Testing is?, Dynamic Testing and Static Testing.

In this tutorial, I am going to explain these things,

  • What SonarQube is?
  • Features of SonarQube
  • Installation and some practice on SonarQube

Let’s Start!

What SonarQube is?

As may you have already guess SonarQube is a static analysis code tool. It basically goes through developers' code and identifies errors at the early stage. It is an open-source static testing analysis software. It is used by developers to manage source code quality and consistency. …


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In this tutorial, we will be learning about SonarQube. It is a Software testing tool used to improve the quality of the code and help fix errors very early in the development. Here are the points which I am going to explain here,

  • What Software Testing is?
  • Dynamic Testing and Static Testing
  • What SonarQube is?
  • Features of SonarQube
  • Installation and some practice on SonarQube (Demo)

I am going to explain these points in a couple of tutorial series.

What is Software Testing?

Software Testing is a part of the Software Development life cycle. …


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Now you know what is Amazon CloudWatch, What it does, and it’s operations. But to understand the capabilities of Amazon CloudWatch completely you should know about 2 important points of Amazon CloudWatch. Those are,

  • Amazon CloudWatch Events, and Charts.
  • Amazon CloudWatch Logs.

Amazon CloudWatch Events

Amazon CloudWatch Events is a part of Amazon CloudWatch which delivers ‘a near real-time stream of system events’ that allows you to ‘monitor and respond to the changes in your AWS resources’ by means of rules that route events to one or more targets.

Now let’s look at a few concepts related to CloudWatch Events.

  • Events — An event indicates a change in your AWS environment. AWS resources generate events when their state changes. Represent small JSON blobs. (Let’s say you terminate active EC2 instance. This EC2 instance has changed to Active to Terminated.) …

About

Kasun Dissanayake

Software Engineer at Pearson Lanka || Former Associate Software Engineer at hSenid Software International

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