Posts

Really quick introduction to GraphQL

What is GraphQL?
Many people think that GraphQL is ‘something’ related to Graph Databases, in my opinion they’re wrong. GraphQL is to Graph DB like Javascript to Java. Are based on similar concepts, but are used for completely different things.

GraphQL is a query language for API’s. Some people name it successor of REST, I’d rather say it supplementor of REST because both can work together. In this article you’ll find good comparison of both.

In short: GraphQL is a query language for APIs, optimized for performance, designed and open-sourced by Facebook. In GraphQL you can ask server for connected data and you’ll get in response only what you’ve asked for. Not more. If you need more information about this, you’ll find it on GraphQL webpage Read more


Welcome to our second article about Keycloak Server! Previously, we’ve learnt to setup the server and make use of it in a webapp -this time, we’re going to create a matching back-end API and also learn a little bit about the OAuth2/OpenID magic that powers our entire authn/authz mechanism. So let’s get started! Read more


Providing authentication and authorization for the non-public-facing components of your application is an important part of many systems. But all major Scala frameworks come ready-equipped with some native tools for doing that, with complexity and comprehensiveness ranging from basic HTTP schemes with Akka HTTP’s SecurityDirectives to numerous Play plugins such as Deadbolt 2 or Silhouette.

But it can be difficult to get what you need out of some of these. And if you have to relearn them for every new framework – it ain’t nice either.

Learn how to overcome the additional overhead when moving to an unfamiliar tech stack!

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S3 (Amazon’s Simple Storage Service) is a popular, widely used object storage service. Uploading a file and storing it on S3 in Akka Http traditionally involves temporarily storing a file before sending it to S3 service. This process can be simplified by using Alpakka AWS S3 Connector. In this post we will take a look at those two different ways and see how they compare with each other. Read more

In this post, we’ll look at what the Typelevel ecosystem looks like in 2018, and how its various libraries interact with each other. In particular, we’ll focus on how we can compose some of these libraries to build a complete application, in a purely functional fashion.

This will not be a tutorial for Cats (there will actually be hardly any code here) – there’s plenty of learning material for that (linked at the end of this post) – but a high-level overview of the ecosystem and the way its pieces interact with each other.

Before we look at the libraries, however, we need to know what Typelevel and Cats are. Read more

A pretty hot topic lately is machine learning – the inter-sectional discipline closely related to computational statistics that lets computers learn without being explicitly programmed.

It has been found to be of significant use in the field of data analytics – from estimating loan and insurance risk to trying to autonomously steer a car in real-life conditions.

In the following post, I would like to introduce to the reader MLlib – a machine learning library that is part of the Spark Framework.
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In this post I will try to share with you all a functional pattern I stumbled upon recently – Tagless Final. This pattern tries to address a vital problem for every software engineer: how to make sure the programs we write are correct?

I will try to explain how Tagless Final works and how it can be applied in practice, while keeping things down to earth and as practical as possible. Of course, I didn’t invent it from scratch, but I would like to share what I’ve learned and maybe popularize this solution.

Kudos to Oleg Kiselyov for describing the pattern in depth and John De Goes for inspiring me to write this post.

Let’s get started. Read more

Introduction

In this article, we will take a closer look at the core of Akka in an attempt to improve its overall performance.

To begin with, we will provide a short overview of the Akka toolkit and the Actor system. Following that we will study the life cycle of a message in order to gain a better understanding of what makes the Akka’s actor implementation tick. We will continue with a brief review of one of the common types of Executor Services that are used in Akka, while exposing its implementation details. Read more

Full source code is available on GitHub.

Introduction

This post is about creating relatively simple project with Freestyle, my adventures during this process and some afterthoughts.

Self-description from the project website: Freestyle is a library that enables the building of large-scale modular Scala applications and libraries on top of Free monads/applicatives. [1]

freestyle logo

I’m limited to single blog post, so I’ll make non-trivial-scale application instead of large-scale one. Precisely it is a module to perform registration and log in with credentials or GitHub’s OAuth 2.0 and http4s server that uses this module in HttpServices (endpoints) for issuing JWT.

This article describes my journey and feelings during it, so it is written in the first person and past tense. Read more

Binding.scala is a one-way data-binding library written in Scala. It lets you create reactive user interfaces by writing concise Scala code. In this post, I’ll guide you step by step through the basics, as well as creating a simple dynamic web page. On top of that, I will discuss some undocumented issues I faced, which might be interesting for you if you decide to give Binding.scala a chance in your next project. Read more