Testing your application’s performance during development as a single user is easy but often misleading. With writing unit- and integration-tests you make sure your main use cases and algorithms work as expected and cover the requirements of the business. Testing the performance of your application under the expected load is often neglected and after deploying…
In addition to my blog post #HOWTO: Up- and downloading files with React and Spring Boot, I want to show you a simple way to display PDF files in the browser with React. I’m using create-react-app to bootstrap the React application. For styling purposes I’ve added semantic-ui-react and semantic-ui-css. The library for previewing the PDF files is called react-pdf: { “name”: “pdf-preview-react”,…
I published my first article on Medium about a habit I started one year ago. To improve my personal development skills, I dedicated at least 30 minutes every day to code and learn something new. Looking back after 365 days, I can totally recommend it to everyone to take time out of the usual schedule…
Recently I got the chance to work through Vlad Mihalcea’s High-Performance Java Persistence Video Course (Version: Mach 2) and in this blog post, I’ll give you a review about this excellent course on tuning your data access layer based on Hibernate and JPA. When starting my career as a Java software developer I had the most headaches while…
Recently I was looking for a simple solution to generate visual documentation of the underlying database. The solution should be easy to use, database vendor independent and automatable e.g. during the CI pipeline. Therefore I found SchemaSpy (GitHub – Homepage) which is a single .jar file and is able to generate nice-looking web-based documentation like the following: Sample…
F or securing your enterprise applications you have several choices which require different configuration setups. Lately, the stateless approach is the de-facto standard for securing your microservice based landscape. With the choice, your applications don’t store session data as the client sends a JWT token with each request and thus the applications know about his metadata…
Bootstrapping a new JSF can be quite cumbersome if you are new to Java EE. Even after weeks of training, I had to look up the anatomy of the or the correct folder structure. As the JSF technology is still a valid and reasoned choice for frontend development in enterprises, I’ve created a simple Maven archetype…
Returning all the data in a table within a REST call can be slow if your table grows. Imagine a simple HTML <table></table> to show all the registered persons in your database. Even if you could return the whole dataset within one HTTP request, the user wouldn’t be able to read them all at once as he…
Recently Andy Wilkinson (@ankinson) from the Spring Boot core team announced the release of Spring Boot 2.1. During the last days, I played around with the new version and will present you the most important updates from my point of view. Spring Boot 2.1.0 has been released: https://t.co/01acMWbF0P. There’s lots of good stuff in this one,…
From the 19th to 21st of October 2018 the Hackathon Digital Tech Summit took place in Nuremberg as part of the Digital Festival in Nuremberg. With more than 500 attendees and 23 Hackathon teams, it was my second and yet biggest Hackathon and my team made the first place. We developed a solution for Siemens…
Writing good unit tests for your central business logic is essential for the speed of your development and a confident deployment to production. But there are also parts of your application where plain unit tests with mocking frameworks like Mockito aren’t that useful or result in a “mocking-hell”. The interaction of your application with your database is…
Manually creating a new Java EE Maven project can be quite cumbersome. Creating all required folders and files for a simple JAX-RS endpoint with a database access was quite error-prone in the past for me. I constantly mixed up WEB-INF and META-INF with its files and was tired of manually creating the project structure. The bootstrapping of a…
Recently Baeldung announced to increase the price of his REST with Spring’s course from $ 249 to $ 299. As I am (or was) a big fan of Baeldung because of his free content about Java & Spring. I purchased the course because I thought I get high-quality and up-to-date content for this amount of money. In…
Recently I had to convert generated .docx files to .pdf files for a more convenient distribution. The Word documents contained some custom formatting and additional pictures. I tried several Java libraries for doing this job (Docx4j, XDocReport and Apache POI) but all of them couldn’t generate the output I got from manually converting the .docx files with Microsoft Word’s native…
Lately, I had the requirement to generate Word documents from specific templates and fill them dynamically with data. For this task, I compared the following Java libraries: Apache POI, iText PDF, Docx4j and XDocreports. I compared them while using the following characteristics: Possibility to replace variables, amount of additional dependencies, lines of code to generate…
Today I want to share a simple approach for up- and downloading files with JavaScript (ES6), React and a Spring Boot backend. This example can be used for any common content type like jpg, pdf, txt, html, png etc. and is not limited to a specific content type. I’ll use the latest version of React (16.4.2…
Recently I had the requirement to limit the access to specific JAX-RS endpoints and to keep track of the user’s current amount of API calls. To solve this problem I asked Adam Bien (@AdamBien) in his monthly Airhacks Q&A about this requirement and he gave me a hint for a possible solution while using the ContainerRequestFilter interface…
For messaging, I have always thought of Apache Kafka as the central solution for messaging. While learning more about Java EE I came along the Java Message Service (JMS) specification and gave it a try. In addition, I wanted to learn more about the JMS capabilities of the Open Liberty application server. In this blog post, I’ll show you how to create a…
Securing your web application can be cumbersome. I recently tried to secure a JSF 2.3 application with the latest Java EE 8 Security API (JSR-375) and it was quite simple. In this blog post, I’ll show you the required configuration steps for securing your JSF application with a form-based authentication mechanism. In the example, I’ll use an…
As my last blog post about a short intro to JavaServer Faces 2.3 got a lot of attention (my tweet got even retweeted by the Java EE Guardian’s twitter page (@javaee_guardian) I want to continue to write about JSF. Today I’ll cover one of the most common use cases for developing web-based applications: displaying/inserting/updating/deleting data…
Scrolling through my news feed on Twitter I get flooded with new releases of npm modules and more and more blog articles about server-side rendering technologies for the latest Single Page Application frameworks like Angular, React. The following tweet summarized my current feelings: As I personally really like React and used it in the past for several projects,…
In today’s post, I want to review the latest technical Java book I read. I came across the book “Java by Comparison” by Simon Harrer, Jörg Lenhard, and Linus Dietz while I was reading Venkat Subramaniam’s blog. Venkat did the foreword of this book and as I am a fan of him, I instantly bought the book….
From July 10th to the 11th I took part in the Hackathon HACK|BAY which was organized by the tech incubator Zollhof in Nuernberg. Even if I participated in several coding challenges and a company internal Hackathon, this was my first Hackathon with a jury and multiple competing teams. The event was sponsored by several local…
In the last weeks, I was searching for a nice solution to send emails to users for one of my side projects. Sending plain text formatted emails with the Spring Boot Mail Starter is quite easy as it is an abstraction using the JavaMailSender interface and auto-configured. It’s also possible to send HTML formatted emails or use…
While I was scrolling through my twitter feed I noticed a post about the new Open Liberty 18.0.0.2 release on June 29. In the official blog post about the new release, they pointed out that Open Liberty now fully supports JavaEE 8 (JAX-RS 2.1, JPA 2.2, JSF 2.3 and so on ..) and that they…
Modeling your domain model with JPA is quite easy and for a smaller amount of data, you can easily rely on the default configuration of JPA/Hibernate. But when it comes to performance issues in your application you need a deeper understanding of JPA/Hibernate. One big performance boost could be Lazy Loading. When it comes to Lazy Loading,…
Today I want to show you a way to avoid repeating the same attributes in your JPA entities over and over again. Let’s say some of your columns (e.g. timestamps for the creation date, the date of the last update, an intern identifier or something else) are present on most of your entities. In most of…
Today I’ll show you a way to write integration tests for your Spring Boot based application with a ‘real’ database and not an embedded database like H2. In the last weeks, I was looking for a solution to write integration tests for my Spring Data based application which was using a Postgres database. I had…
In today’s #HOWTO blog post I want to show you a way to expose git information (like commit hash, commit timestamp, branch …) of the deployed application via Spring Boot’s Actuator dependency. If you are not versioning your Maven application with the <version>X.Y.Z</version> tag and you want to know which state of your application is deployed to…
In today’s #Review post I want to blog about one of my latest Java books: Effective Java. I was looking for a more advanced book about Java and therefore I found this book from Joshua Bloch. I bought the third edition of this book which was updated on 27th December 2017 for Java 7, 8 and 9….