Tech Trek: A Software Engineer's Guide to Code and Beyond

This guide walks you through the steps of registering an application to integrate with Facebook. Register a new application From  http://developer.facebook.com , click on "My Apps" at the top of the page to go to the application dashboard. The dashboard shows a list of applications that the developer has already created or you can create a new one by clicking on  Add a new App.   A dialog prompts you to name your application. Enter Display Name, Contact Email and Choose a category from drop down list and click on  Create App ID . After you click, Facebook performs a Captcha check to verify that you’re not setting up applications through an automated process. Once you’ve satisfied the verification process, your application is created. The next page you see is your application’s application page. Click on the  Settings  button and it will open you a setting page of your application. Now we can configure various det...

Prerequisite : Understanding of JWT or read here to understand what is JSON Web token. As we already know that JWT is special because it is digitally signed and we can verify the authenticity of JWT using signature. Today, we will discuss on how we can actually sign this JWT using Symmetric and Asymmetric key. Symmetric key: Symmetric key uses the same key for the signature generation as well as at the time of token verification. So, extra precaution is required during the exchange of the secret key between sender and receiver. Use symmetric key if there is one sender and one receiver, the exchanging of the key will be easy.  Eg: One web application talking to the backend services. Asymmetric key: It uses a key pair. The key pair consists of a public key and a private key. JSON data will be signed using the private key and can be verified using the public key. Use Asymmetric key if you have one sender and multiple receivers as you cannot share the same key...

You should be aware of Synchronization if you are working on an application where multiple threads are accessing the same resources or else it will show you erroneous or unforeseen results. Imagine a scenario where you are doing the multiple transactions in your bank. I believe you don’t want one thread is updating your balance and in parallel, the other thread is reading your balance otherwise you will end up in error or unexpected results. Example 1: Public class HDFCBank {             Protected long balanace =1000;             Public void deposit( int amount) {                         this.balance = this.balance + amount;             } } Assume if two threads, A and B are executing t...

How to control logging with Spring Boot? By default, the SLF4j Logging is included in the Spring Boot starter package. To enable logging, create a  application.properties  file in the root of the  resources  folder. 1. application.properties logging.level.org.springframework.web=ERROR logging.level.com.waheedtechblog=DEBUG # Logging pattern for the console logging.pattern.console= "%d{yyyy-MM-dd HH:mm:ss} - %msg%n" # Logging pattern for file logging.pattern.file= "%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{36} - %msg%n" logging.file=/Users/waheed/application.log Similarly we can configure in application.yml as well. 2. application.yml logging:   level:     org.springframework.web: ERROR     com.waheedtechblog: DEBUG   pattern:     console: "%d{yyyy-MM-dd HH:mm:ss} - %msg%n"     file: "%d{yyyy-MM-dd HH:mm:ss} [%thread] %-5level %logger{3...

The simplest way of creating Spring boot with MySQL application is via Spring starter project using STS (Spring Tool Suite) IDE. Steps: Create a new project by selecting spring starter project wizard Select project type as Maven, provide project name, packaging, and Java version etc. Select spring boot version and project dependencies After finishing, It will create the project structure with all required dependency. Configure MySQL configuration in application.properties file Now, Create the @Entity model ( User ) which should be persisted in the database . Hibernate will automatically translate entity class into a table. Create the repository (UserRepository.java ) . The Repository interface will be automatically implemented by Spring in a bean with the same name with changing case. For UserRepository, the bean name will be  userRepository . To handle HTTP request, Create a Controller class (UserController.java) having method POST a...

As we know that there are various ways for creating Spring Boot application. For this sample application, I am going to use STS (Spring Tool Suite) IDE. Steps: Create a new project by selecting spring starter project wizard Select project type as Maven, provide project name, packaging, and Java version etc. Select spring boot version and project dependencies After finishing, you can see the project structure as shown below Spring boot generates a Java file in the  src/main/java  directory, pom.xml file with all required dependency.  T o handle HTTP request, Create a Controller class Now run the  SpringBootExampleApplication.java  as a Java application. It will start the tomcat server on default port i.e. 8080 Open browser and hit url http://localhost:8080/application Note: By Default, Application will start on port 8080 but can override by adding server.port to application.properties file....

Spring Boot Initilizr is a web tool which is provided by Spring on official site using which Spring Boot project can be created by providing project details. It simplifies Spring Applications Development by providing initial project structure and build scripts which reduces development time thus increase productivity. Steps to create Spring Boot project via initilizr ·         Select Maven project and dependencies. Fill other details as shown below and click on generate project. ·         Download the project, extract and now import this project As Maven by using Import option from the STS (Spring Tool Suite) IDE. ·         After finishing, You can see the project structure as shown below: ·      Spring boot generates a Java file in the  src/main/java  directory, pom.xml file with all required dependency. The default created Java ...