A Java geek

A use-case for local class declaration

One of the first things one learns when starting with Java development is how to declare a class into its own file. Potential later stages include: Declaring multiple classes into the same file - with at most one of them publicDeclaring static nested classes or inner classesDeclaring anonymous (inner) classes But this doesn’t stop there: the JLS is a trove full of surprises. I recently learned classes can be declared inside any block, including methods.

Development

ElasticSearch API cheatsheet

ElasticSearch documentation is exhaustive, but the way it’s structured has some room for improvement. This post is meant as a cheat-sheet entry point into ElasticSearch APIs.

Java

Signing and verifying a standalone JAR

This is the 3rd post in the JVM Security focus series. Last week, I wrote about the JVM policy file that explicitly lists allowed sensitive API calls when running the JVM in sandboxed mode. This week, I’d like to improve the security by signing the JAR.

Java

Proposal for a Java policy files crafting process

This is the 2nd post in the JVM Security focus series. I’ve already written about the JVM security manager, and why it should be used - despite it being rarely the case, if ever. However, just advocating for it won’t change the harsh reality unless some guidelines are provided to do so. This post has the ambition to be the basis of such guidelines. As a reminder, the JVM can run in two different modes, standard and sandboxed.

Java

Compilation of Java code on the fly

Java makes it possible to compile Java code at runtime… any Java code. The entry-point to the compilation is the ToolProvider class. From its Javadoc: Provides methods for locating tool providers, for example, providers of compilers. This class complements the functionality of ServiceLoader. This class is available in Java since version 1.6 - released 10 years ago, but seems to have been largely ignored.

Technical

Exploring data sets with Kibana

In this post, I’d like to explore a sample data set using Kibana. This requires some data to start with: let’s index some tweets. It’s quite straightforward to achieve that by following explanations found in my good friend David’s blog post and wait for some time to fill the index with data. Basic metric Let’s start with something basic, the number of tweets indexed so far. In Kibana, go to Visualize Metric, then choose the twitter index.

Technical

Open your classes and methods in Kotlin

Though Kotlin and Spring Boot play well together, there are some friction areas between the two. IMHO, chief among them is the fact that Kotlin classes and methods are final by default. The Kotlin docs cite the following reason: The open annotation on a class is the opposite of Java’s final: it allows others to inherit from this class.

Technical

Feedback on Feeding Spring Boot metrics to Elasticsearch

Some weeks ago, I wrote a post detailing how to send JMX metrics from a Spring Boot app to Elasticsearch by developing another Spring Boot app. Getting to create such an app is not always the right idea but developers are makers - software makers, and developing new apps is quite alluring to them. However, in the overall scheme of things, this means time is not only spent in development, but also for maintenance during the entire lifetime of the app.

Technical

Exploratory Infrastructure projects

Nowadays, most companies use one or another Agile methodology for their software development projects. That makes people involved in software development projects at least aware of agile principles - whether they truly try to follow agile practices or just pay lip service to them for a variety of reasons remains debatable. To avoid any association with tainted practices, I’d rather use the name 'Exploratory Development'.

Nicolas Fränkel's blog