ZIO is a type-safe, composable library for asynchronous and concurrent programming in Scala (from: The ZIO github). The ZIO framework provides your program as immutable and pure values, which are very simple to properly unit test. But how can you run an integration test to see if your application starts up properly?
Spring Data repositories allow you to easily query your entities with method names such as findByUserName(String name).
However, it can get cumbersome to always retrieve, pass and match on the active user.
Luckily Spring Security integrates well with Spring Data to minimize the overhead.
This post is part of a series of blog posts on Spring Security; the code can be found on GitHub.
Spring Data enables you track who modified an entity and when, with just a few annotations. When combined with Spring Security, you can set this metadata based on the active user.
This post is part of a series of blog posts on Spring Security; the code can be found on GitHub.
Distributed tracing is a method used to profile and monitor applications, especially those built using a microservices architecture. Distributed tracing helps pinpoint where failures occur and what causes poor performance.[1] Applied to Kafka Streams it allows us to trace and visualize our messages by propagating diagnostic information within message headers.
Using the Stream API and the map method we can transform elements in a stream to another object. Instead of using the map method we can also write a custom Collector and transform the elements when we use the collect method as terminal operation of the stream.
First we have an example where we transform String values using the map method:
I have seen the following pattern appear quite a lot:
private String foo(String bar) {
if(bar != null){
return "bar";
}
return null;
}Here the function is called with a nullable argument, and if the argument was null, the function will return null, and if not it will return a proper value. I do not like this, and here is why.
The Kotlin standard library contains a lot of helper functions on top of the Java standard library for our convenience.
Some of those functions help us in converting between different data types.
For example, the String.toInt() function converts a number formatted as String to its Int representation.
But how do we accomplish the same with a Char? Spoiler alert: NOT by using Char.toInt(), but by using Char.digitToInt()!
Functions defined in Kotlin companion objects are often seen as the 'equivalent' of static methods in Java. Although there are some similarities, there are also some caveats you should be aware of. For example, how to use method references (or, to be pedantic: function references) to refer to functions defined in a companion object.
Since about a month I’m developing some microservices using Javalin, a small, simple and lightweight web-framework that started as a fork from SparkJava. By now it’s a ground-up rewrite, influenced by the Javascript framework koa.js. Don’t let the stuff like Either scare you, we use the Arrow library to make our life a bit more easy :)
When requesting user input from a form, it’s evident that we need to validate our input. Javalin has its own way of doing so (from the docs):
Now that it’s clear how to use an OAuth access_token in JWT to perform RBAC inside a REST service playing the role of resource server, it is time to see how to acquire such a token.
