JCON 2018

Kotlin EE: Boost your Productivity

October 11, 2018 | 14:00 | Kino B

Kotlin is a language for the JVM, invented by JetBrains a few years ago. But what the hell is Kotlin EE? If you never heard of Kotlin EE, don’t panic, it does not exist. But you can use it right away and boost your productivity!

I invented the term Kotlin EE as a synonym for using the Kotlin language together with the Java EE API to create services of any size (microservices, nanoservices etc.) with just a few lines of code and the ability to focus on the business logic.

Kotlin and Java EE are a perfect couple for writing micro- or nanoservices. Kotlin is a very pragmatic language, builds on many concepts and techniques from Java, designed for developer productivity. Kotlin works great with all existing Java libraries and frameworks and runs with the same level of performance as Java.

The Java EE API allows us to code against a proven and stable API. Provided libraries like JAX-RS for writing RESTful APIs and Jackson for JSON (de)serializing decrease the need for additional third-party libraries which results in a short build time and a small artifact size. Benefit from a very fast build and test feedback and stay focused on your code.

In this talk, I try to prove my statements from above. Live on stage I write a service in Kotlin with a RESTful JSON API with only a few lines of code and run the service using a local Docker cloud where you can see how these can be scaled up and down to manage fluctuating loads. Coding, building, testing, deploying, scaling: fast and efficient!

Let’s have some fun with chat bots!

October 11, 2018 | 17:15 | Kino A

A lot of companies are investing in chat bots. In this workshop, we will develop a fully functional chat bot from scratch with support for formatted messages, photos, documents, locations, buttons, custom keyboards and more. No slides, just code – and a lot of fun…

Do you understand the user interface of every website and every application? I don’t! Do you understand how to use a chat application like WhatsApp, Telegram, Threema, Signal, Facebook Messenger, etc? I do! If everyone knows how to chat, what if we provide our business services using a chat bot as a user interface? Let’s have some fun and create a chat bot live on stage as an introduction to this very interesting topic!

This talk has no slides – it’s all about code! Live on stage I start a new empty project and show the audience how to write a complete and working chat bot from scratch for Telegram. Our bot will receive messages from other Telegram users, analyze them and send an appropriate answer. The messages can be formatted and contain photos, documents and locations. We will use custom and inline keyboards, callback buttons and much more.

This talk is kind of interactive – the audience can use a Telegram client on their own devices to talk to the chat bot while I’m working on it live on stage.

To fully understand this talk the attendees should have basic knowledge of Java.

Go for the Money! JSR-354

October 11, 2018 | 18:15 | Kino D

In the last years the development of the Java language itself is going on more rapidly and some long-awaited features were implemented. The best-known are the new Date & Time API and Lambdas & Streams. Specially for business applications there was another very interesting feature released in May 2015: JSR-354 – Money and Currency API

What is this JSR about, why is there a need for a Money and Currency API? After answering these questions I provide an overview about the new API, their packages and classes with usage examples. I show how to calculate with money objects, how to convert between currencies, how to format and how to parse values using the Money and Currency API.

The Money and Currency API is compatible with Java 8 and newer. At the end of my talk there is a demonstration, where I show how an application can use the new Money and Currency API in practice. To fully understand this talk the attendees should have basic knowledge of Java.

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