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Showing posts from 2021

Get started Oracle DB Express for development

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Oracle database is a Relational database developed by Oracle, Oracle DB provides high performance with failure recovery features, easy to manage the database, and has a good reputation for supporting Enterprise level applications. For you database admin or software developer that are newly using Oracle database, you can follow this simple get started guide. Follow each one of the instructions from installation to launch and create a new database table. Download and install Oracle DB Download the oracle database express edition from the following link : https://www.oracle.com/database/technologies/xe-downloads.html When the installation process is running, then you should set the default password that you will use for login. Login using SqlPlus Open terminal or command prompt and type "sqlplus”. Then enter the username SYSTEM and password you choose on the installation step earlier. Create new user Before the SYSTEM user can create new user, you have to execute this command: alter

Upload and Download Rest API using Spring Boot Reactive WebFlux

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Reactive Spring Logo This is maybe a very simple task, but for those of you that may not be familiar with WebFlux found it difficult to create a Rest API that handles upload and download in Reactive spring application. Create the skeleton Spring project Create a new project, go to start.spring.io , on the dependencies section, add Spring Reactive Web. Generate and extract it into your desired project location. Instead of using spring-boot-starter-web, use spring-boot-starter-webflux instead in your pom.xml. Here’s the pom.xml for our Reactive Rest API project. Create our Rest controller Now that you have set to use WebFlux instead of the usual web, we have to change a little bit in the Controller class that handles the API endpoints. It doesn’t change much but you have to wrap the Response in Mono and the request parameter to FilePart. So our upload and download file controller will look like this. Create utility to handle file upload We need to structure our project better, so we cr

Spring Kafka - how to use ReplyingKafkaTemplate send and reply synchronously

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Microservice Spring with Apache Kafka Kafka is an asynchronous messaging queuing system, but when you have a case in your project that you need to have the result immediately from another service you can do that quite easily. Kafka from the client side produces a message to the server side, then waiting for the server to return back the message exactly what the client wants. It’s identified in the kafka header request named KafkaHeaders.CORRELATION_ID and a topic where the server should send. If the server side produces the same correlation id to the same topic in the request, then the client side will catch that message as its reply. Although you can work with kafka from a different framework and language other than Java and Spring. Here’s in this example i just specifically giving the example of sending and replying kafka messages using Spring Boot. The Project Overview The client-project will send a string message to the server-project over kafka, then the server-project wil

Start small! You don’t have to solve world most difficult problem

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Start up meeting - Image by StartupStockPhotos from Pixabay You don’t have to create new business or solve the world's most difficult problem. You can just start a small doable business by following other businesses that already exist, as long as you have better product, packaging and marketing. People are too ambitious and think too far, it’s okay if you are Elon Musk, but if you just some random guy creating your own business, although it is possible to compete in space race, its chance is very slow compared to already exist doable business that you can just start So, start small, don’t overthink things. Only when your capital is significantly larger, only then you can start to think about expanding your business. Most businesses will fail before 1 year, so be careful, you have to manage your resources carefully. I read the book Atomic Habits, which can be summarized the following: Atomic Habits by James clear is a definitive guide for breaking bad behaviors, showing you how sma

5 Advices About Writing A Tech Blog For Beginner

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Blogger with laptop - Image by Peter Olexa from Pixabay Today’s is not going to be a technical tutorial about how to do stuff in some programming language or fixing some bug in some programming technique. It’s just my overall view about blogging without any preparation or research, it’s purely written straight from the document editor. As I am now a self-proclaimed tech blogger, because I feel I have written enough articles to have myself categorized as a blogger. I will be giving some advice about writing a tech blog, but this is for beginners. So, if you are not a beginner, maybe this is not the right article for you. Consistency Writing a blog is not easy, in fact it is very hard that every beginner will leave their blog untouched after a few tries writing less than 20 posts. For me the hardest part of writing a tech blog, or any other niche blog is the consistency, because we don’t always have perfect time, or perfect mood to develop a written article. To be consistent writing on

Better Understanding of ACID Principle In SQL Database

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ACID principle in SQL database ACID  is a set of principles whose acronym is Atomicity, Consistency, isolation and durability. As any other principle, it’s done by the developer or database admin or available feature on the database system of choice (MySQL, Postgres, SQL server). So as a developer or data admin you must know this principle in order to design and develop a database system for your project. Dealing with database transactions that have many queries in it should be handled following the ACID principle. When a set of queries are executed ACID prevents disaster in your data because something that is partially error in the middle of transaction can lead into data inconsistency. Because the app query expects all the query should be completed with no interruption, sometimes your database depends on other data. So here’s what ACID principles acronym are: Atomicity All queries in a transaction are treated as a single thing, if one query fails, the whole thing shouldn’t change any

Some Common Java Developer Interview Questions In 2021 Onward

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Job Interview - Image by Sue Styles from Pixabay If you are a software developer currently looking for a job, these are some common questions that the interviewers usually ask you. So, you better prepare. The question in the interview process will range from basic to technical questions. The basic questions will assess your experience in your previous job. If you are just a fresh graduate, you just have to tell them about the internship and your contribution. If you are already working in a company, again the principle to answer all the questions is the same, just share your contribution on the team of your company that you work before. In my experiences applying for a software developer job, there’s not going to be tricky questions actually, it rarely happens. Tell me about yourself? This question is simply asking your experiences in the software development industry, just it, nothing else. To answer this question, you need to tell in detail what’s So as relax as you can, tell the in

How to start develop Spring Boot application from Notepad

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While writing our codes in Java is easier done using specialized Java IDE (integration development environment) like Eclipse, VS code, IntelliJ, there’s actually no requirement to make your java application. You can just write the code using any tools. The advantage of writing codes in a simple editor like notepad is the lightness of the program, when writing codes in IDE it just feels sluggish when we are typing on it. Because in Notepad, you won’t be given any code suggestions, like method, variable, class etc, so you are typing faster. It can be cumbersome for new developers writing java code in a simple editor, but it is worth a try. So, let’s do it. 1. Install notepad++ We are not going to use the default windows notepad, it’s too ancient to do basically anything, so let’ s just give you the improved version of notepad, the notepad++. You can download from the web official download page here https://notepad-plus-plus.org/downloads/ . 2. Create spring boot skeleton app Go to the pa

What's the advantages of SOLID principle in OOP Java

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SOLID Principle In OOP Java As is our nature of laziness, we tend to write codes as if we don’t look for future potential disasters. As long as the codes work, it will just work fine. And I even recommend that if you are just beginner coders, you shouldn't care much about what principles you should use to write code. The first step of becoming a developer is just writing lots of code, no need for structure, or anything else, the only thing that matters is that the code works and returns output as it expected. In other words, you need to master the code's syntax, setup, debug, the environment, etc. As you gain many experiences over the years as a software developer, then you will have the sense to write better code, at this point, you start to look at design principles, design patterns etc. The Advantages of the SOLID Principle? In object oriented programming (OOP), we must know about the SOLID principle on writing better codes. But why should we use SOLID principles? - The Soli

How to reverse string in Java without built in library

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Reversing string in java is available via StringBuilder class, we can use stringBuilder.reverse(), then it magically reverses the string. But like an interview task for a Java developer job, sometimes the interviewer wants you to test your algorithm ability. So we have to do it manually, but don't worry it’s not that hard to reverse a string in Java. The thing that you need to do to reverse the string is basically just split the string into arrays of characters, and then loop all those characters through the array, and combine all the array but from the back. And This is simple java code not using Java built in library that you can just copy paste for reverse a string in Java. And here’s the comparison if you want to use String builder, it’s much cleaner and if you want to do it in real life, it’s much better using this way. Java is a magical language, it’s general purpose higher level language support for developing scalable, from personal to enterprise application, with lots

Java error Compilation failure Source option 5 is no longer supported

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Java and Maven - Packaging Manager This is a very common error for a beginner java for the first-time using maven. When you are compiling your Java application using Maven dependency management version 3.6. The following error will occur. - Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project java-test: Compilation failure: Compilation failure: - Source option 5 is no longer supported. Use 6 or later. - Target option 1.5 is no longer supported. Use 1.6 or later. The solution is pretty simple, you just have to make sure you are using Java version 6 or higher. Then place this configuration in your pom xml.     <properties>         <maven.compiler.target>1.8</maven.compiler.target>         <maven.compiler.source>1.8</maven.compiler.source>     </properties> Now you can execute this following maven command on your project application, using maven commands to package your project into a jar like th

Intellij Lombok Run Error Method Not Found

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Java Maven Project Lombok Intellij This kind of error happens to me recently when I am working with microservices Spring Boot   Java application. When I use git, I usually gitignore the “.idea” configuration so when I switch between different branches meanwhile the “.idea” doesn’t change because it is being ignored, then the IntelliJ does not configure the project correctly. The solution is simply by removing the “.idea” folder, the “.iml”, IntelliJ project configuration. And reopen the project from IntelliJ . And the “target” folder, which is your java maven project build folder, some sort of caching mechanism. Then you can open the terminal and CD to your project and simply run maven rebuild commands like the following. All you need to do right now is to clean the project and then package your maven java project. mvnw clean package Now, try to run your project using the green triangle button that is usually used for running your maven project on the IntelliJ IDEA. That’s it, I hope t

4 Marketing Principles to Learn for Beginners

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4 Marketing Principles to Learn for Beginners Starting into a marketing business is so difficult, you can’t just say you jump knocking the door and offering a product to the customer, although it is practically possible, it’s not going to be very efficient in current day market situations. Here are a few beginners marketing principles to learn if you are just starting in marketization of your product, or company you are working in. Specialization Specialization is determining where you are going to specialize which your product or service is categorized. It can be a product or service, or it can be a particular market area that you want to work in. For example, McDonald's customers are people who want to eat quickly and they want cleanliness, efficiency, value, price and pleasant surroundings. What they will do is they will offer every product that they possibly can for people who want to eat quickly whether it's a burger, milk shake, ice cream, coffee serve based on that speci

Event Driven Microservice Spring Boot with Apache Kafka

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Apache kafka logo Apache Kafka in simple terms is a collection of logs of events when some data in a database changes, divided into topics. This is why it is called event driven architecture, when some service saves data in a database, you use Kafka to produce an event so that other services (wherever it is located) can listen on that event and do some computation whatever they want based on the event that is firing. Kafka is usually used for microservices architecture, so instead of reading data from a database, each microservices communicate with Kafka events, which we call produce and consume. Produce is Kafka term to emit a message to a specific topic, meanwhile consume is to listen to an event that contains data that is produced by some other microservices. Monolithic application Microservice architecture application What is Event-driven Microservices Microservice design is a way to develop an application and split it into small independently deployable services, each microservice

What is a database system in information technology?

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Database server infrastructure - Image by Colossus Cloud from Pixabay In Information Technology (IT), a database is an infrastructure that can store collection of data. Storing data in a database makes the data more structured and can be controlled easily. Saving and retrieving data with a given set of commands or queries, that is more popularly called structured query language (SQL). Nowadays, IT database systems can be divided into two major popular different type, RDBMS         and NoSQL database. RDBMS is pretty old, meanwhile NoSQL is the new kid that is trying to get more and more attention from the developer community because it allows for high-performance, agile processing of information at massive scale. RDBMS The Relational Database Management System or Relational database is a database System that is known as an advancement version of DBMS database system. If we talk about RDBMS, we cannot separate it by its SQL language. An SQL or structured query language is a standardi

What's worth the money to be rich and successful

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Britney Spears wireimage Commercial appeal The young Britney Spears has commercial appeal. It's very rare to hear someone that age who can deliver emotional content and commercial appeal. For any artist, the motivation, the 'eye of the tiger' is extremely important. And Britney had that. The eye of the tiger A feeling of confidence and power is the key not only for gaining commercial benefit, but also for everything that one wants to achieve. The strength and confidence of someone determines success for whoever they master those traits. Characteristics of a success They follow their own dream; they pursue mastery and understand that money is a by-product of the value they offer. they are not multitasking people; they are more focused on one thing they believe they can make it. No worry and no fear, what doesn't kill you makes you stronger. They take action and are very optimistic. How to sell a pen Understand what kind of person you are selling to. Hype about the pen yo

Online Platform to Compete and Test How Quick You Are At Typing

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If you are a computer geek like me, typing is one of the routine activities you must do every single second. Having the ability to type faster than other people is a set of skills that you can be proud of. It is not easy to train yourself to have very quick typing ability. Typing faster can also be a valuable skill some companies may demand. There’s no other better online program that you can test your self-ability of typing, how fast you can type other than using this online platform called typeracer.com. About Typeracer.com The award-winning online typing competition, TypeRacer, allows people to race each-other by typing quotes from books, movies, and songs. It is the first multiplayer typing game on the web. Since launching in March, 2008, millions of people from all over the globe have completed hundreds of millions of races on typeracer.com, improving their typing speed by as much as 50 words-per-minute. TypeRacer is available in 50 different languages. How to compete on Typeracer

10 Most Quora Best Questions and Answers

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Quora's best questions and answers Photo by Clay Banks on Unsplash This is such a big topic that cannot be justified by one single blog post. There are so many questions in the world that have been around and some are meant to never be solved because the universe has always had a secret. And some questions are just comforting to us to know the answer, that can give us light and hope when we feel lost in life's unending struggles. Some Quora answers are just top and well written, that make you feel guilty for reading that valuable material for free. It feels like it deserved more than as it is just free to read, sometimes we don’t even recognize who's the person writing that answer, truly they deserved more out of it. Here are some 10 most Quora’s best question and answers that in my opinion is life changing reading material. It gives me comfort and better understanding on how to act better to survive and thrive in this journey of life. 1. What is the meaning of life? Asim

How to create website in 2021 for free, quick and stunning

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Nowadays, creating a new website is something that everyone can do. Starting for free design to quality paid themes, but usually a free website to start with is not something that will look embarrassing. You can make your free website look more professional by learning web design. Firstly, you need to know that a website with your personal brand domain name is not going to be free, you need to pay about $10 to buy your domain name, something like yourname.com or yourname.org. Or any other domain you want. 1. Find free website builder I am not going to make any promotion about website builders in this tutorial so, this is a genuine post about choosing a free website builder. What I mostly do is by searching everything on Google. So to find free website google, search on Google: build website free And when the result comes out, click on the first website that appears, usually the best website that appears at the very top is already the best for website builders. And already have lots of

Feel unhappy with your new you job, how to deal with moving to new job

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Stress and Anxiety Photo by whoislimos on Unsplash I’m just a few days working at my new job, it just feels horrible. I was so stressed, anxious about the next day, and felt helpless, wanting to cry and just feel unhappy. Even though I have so much experience, at this new job, everything feels new to me and there is still so much to learn. I almost give up and want to quit and go back to my old job, where everything is just so much fun. But there's no way back, I have already quit and there’s no way I can just give up from moving forward with my dream. I feel like It’s not that I don’t know. But more like that I am so overwhelmed that I can’t think straight. Then I started to question my decision to change careers. I feel like this is not a good decision. I was thinking of not coming back to that new office, that's how overwhelmed I feel. I think I am too much confident that whenever moving to a new place I would just feel nothing, but actually there's a lot more than that

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