Learn about fine-grained inheritance control in Java Sealed classes feature was released in Java 17. However it was already available as a preview feature since Java 15 and revised in Java 16. Sealed classes can restrict other classes or interfaces from extending or implementing them. In short, this feature allows…

JavaScript DBMS with an API inspired by CouchDB PouchDB is an open source client-side database API written in JavaScript. It is modelled after CouchDB — a NoSQL database that runs within the browser. If you are not familiar with NoSQL databases, let me give you a short introduction. NoSQL is…

Messaging Queue enables asynchronous communication, where application puts a message onto a message queue and does not require an immediate response to continuing processing. The producer and consumer do not interact directly with each other, but they interact with message queue. This way of handling messages decouples the producer from…

A guide to use Spring Expression Language with @Value annotation. Spring Expression Language (SpEL) is a powerful expression language, which can be used for querying and manipulating an object graph at runtime. SpEL is available via XML or annotation, is evaluated during the bean creation time. In this article, we…

Many applications need to run some sort of scheduled tasks for chores like system maintenance, administration, taking a daily backup of data or sending emails. A Cron is a time-based job scheduler, which enables applications to schedule a job to run automatically at a certain date or time. There are…

Multi-threading is similar to multitasking, but enables the processing of executing multiple threads simultaneously, rather than multiple processes. The CompletableFuture, was introduced in Java 8, provides an easy way to write asynchronous, non-blocking and multi-threaded code. The Future interface which was introduced in Java 5, to handle asynchronous computations. But…

GraphQL has been gaining popularity and it has made its way to the forefront of API development. There are several GraphQL clients available today for front-end frameworks. Apollo client is one of the popular clients for Angular applications. In this article, we are going to build a small application using…

GraphQL is a query language for APIs that allows clients to request limited data they need, making it possible for clients to gather data in a limited number of requests. GraphQL is strongly typed protocol and all data operations are validated against a GraphQL schema. In this article, we will…

Most communications between microservices is either via HTTP request-response APIs or asynchronous messaging. While these two mechanisms are most commonly used, yet they’re quite different. It is important to know when to use which mechanism. Event-driven communication is important when propagating changes across several microservices and their related domain models…