Java 8 comes with a new Optional type, similar to what is available in other languages. This post will go over how this new type is meant to be used, namely what is it’s main use case.

What is the Optional type?

The terms “modularity” and “microservices architecture” pop up quite often these days in context of building scalable, reliable distributed systems. Java platform itself is known to be weak with regards to modularity (Java 9 is going to address that by delivering project Jigsaw), giving a chance to frameworks like OSGi and JBoss Modules to emerge.

When I first heard about OSGi back in 2007, I was truly excited about all those advantages Java applications might benefit of by being built on top of it. But very quickly the frustration took place instead of excitement: no tooling support, very limited set of compatible libraries and frameworks, quite unstable and hard to troubleshoot runtime. Clearly, it was not ready to be used by average Java developer and as such, I had to put it on the shelf. With years, OSGi has matured a lot and gained a widespread community support.

Introduction

All projects I’ve been working on have used database connection pooling and that’s for very good reasons. Sometimes we might forget why we are employing one design pattern or a particular technology, so it’s worth stepping back and reason on it. Every technology or technological decision has both upsides and downsides, and if you can’t see any drawback you need to wonder what you are missing.

In this post I will present how to connect to MongoDB from a stateless Java EE application, to take advantage of the built-in pool of connections to the database offered by the MongoDB Java Driver. This might be the case if you develop a REST API, that executes operations against a MongoDB.

This post will explain in a simple way how Javascript Closures work. We will go over these topics and frequently asked questions:

• What is a Javascript Closure
• What is the reason behind the name ‘Closure’
• Actually viewing closures in a debugger
• how to reason about closures while coding
• the most common pitfalls of it’s use