Part of java - 2 groups

Java Vienna

Vienna, AT

3,102 members · Public group

Organized by Dominik Dorn and 2 others

What we’re about

Java & JVM in Vienna, Austria: An in-person meetup for local enthusiasts.

Our monthly meetup (except for July and August) in Vienna provides a platform to discuss various Java-related topics such as frameworks and best practices. The meetup is aimed at beginners, intermediates, and professionals alike.
Please note that our meetings are in-person only and primarily intended for individuals living in or near Vienna.
We meet at the Vienna University of Technology in the heart of the city. If you have something interesting to share that is not widely known, please feel free to reach out to one of the organizers.

Java & JVM in Wien, Österreich: Ein persönliches Meetup für lokale Enthusiasten.

Unser monatliches Meetup (ausgenommen Juli und August) in Wien bietet eine Plattform, um über verschiedene Java-bezogene Themen wie Frameworks und bewährte Methoden zu diskutieren.

Das Meetup richtet sich an Anfänger, Fortgeschrittene und Profis gleichermaßen.

Bitte beachtet, dass unsere Treffen ausschließlich "in-person" stattfinden und hauptsächlich für Personen gedacht sind, die in Wien oder der näheren Umgebung leben.

Wir treffen uns an der Technischen Universität Wien im Herzen der Stadt.

Wenn ihr etwas Interessantes zu teilen habt, das noch nicht allgemein bekannt ist, zögert nicht, einen der Organisatoren zu kontaktieren.

Upcoming events (4)

See all

Mon, May 5, 2025, 6:00 PM CEST"JVMTI: what's the JVM Tool Interface" + "Fun with Flags: OpenFeature"
TU Wien, Freihaus HS1, Vienna
Agenda

18:00 doors Open
18:20 Welcome
18:30 JVMTI: Introduction and use cases for the JVM Tool Interface - Kevin Watzal
19:30 Break/Networking
19:55 Raffle: IntelliJ + OrbStack.dev Licenses
20:00 Fun with Flags: Bringing the Fun Back into Feature Flagging with OpenFeature - Simon Schrottner
21:15 Networking

JVMTI: Introduction and use cases for the JVM Tool Interface
Ever wondered how profilers track memory allocations or how they can measure the methods that use most of the CPU resources without knowing your code?

Meet JVMTI — the Java Virtual Machine Tool Interface, that allows tracking, inspection and modification of JVM applications. Track the states of your threads, trace objects as they follow the flow of your application or modify instance values at runtime. Learn how JVMTI works, how profilers, debuggers and other tools rely on it and find interesting ways to solve issues of your application. Lastly, see how security researchers monitor JVM applications to help protect users and organizations.

About the Speaker
Kevin Watzal is a Software Developer with a passion for the JVM for nearly 10 years. He currently works in the e-mobility sector, specializing in fleet management and electric vehicle charging solutions.

His motto, “Knowledge is power,” reflects his enthusiasm for exploring new libraries and frameworks to continuously discover innovative problem-solving techniques. Alongside his professional work, Kevin pursued part-time studies in IT Security, with a master’s thesis that focused on the security analysis of JVM applications using JVMTI.

In addition to his expertise in software development, Kevin is also passionate about sustainability and nutrition.

Fun with Flags: Bringing the Fun Back into Feature Flagging with OpenFeature
Feature flags have revolutionized the software delivery lifecycle, enabling teams to decouple releases from deployments and create a more agile development process. They're often hailed as one of the key practices in modern software development—at least in theory.

However, as systems grow in complexity, so do the challenges associated with feature flagging. From supporting multiple languages and managing targeted evaluations to avoiding vendor lock-in and safely decommissioning obsolete code, what initially seems like a straightforward problem can quickly become daunting.

The OpenFeature community is tackling these challenges head-on by providing vendor-agnostic SDKs and a suite of powerful tools designed to simplify the feature flagging experience. Join me as we explore the common pitfalls of feature flagging and discover how OpenFeature can help bring the fun back into this critical aspect of software development.

About the Speaker
TBA
51 attendees+46
Mon, May 19, 2025, 6:00 PM CEST"Engineering a better Java build tool" + "Vaadin 24 in the real world"
TU Wien, Freihaus HS1, Vienna
Joint Meetup with Scala Vienna

Agenda:
18:00 doors open
18:20 organizational stuff
18:30 - 19:30 Mill: Untapped Potential in the Java Build Tool Experience - Li Haoyi
19:30 - 19:55 Pizza break
19:55 - 20:00 Raffle
20:00 - 21:00 Vaadin 24 in the real world - building the Java Vienna Raffle! - Sebastian Kühnau

Untapped Potential in the Java Build Tool Experience
The Java language is known to be fast, safe, and easy, but Java build tools like Maven or Gradle sometimes don't quite live up to that standard. This talk will explore what "could be": where current Java build tools fall behind modern build tools in other communities, in performance, extensibility, and ease of getting started. We will end with a demonstration of an experimental build tool "Mill" that makes use of these ideas, proving out the idea that Java build tooling has the potential to be much faster, safer, and easier than it is today.

About the Speaker
Li Haoyi graduated from MIT with a degree in Computer Science and Engineering, and since then has been a major contributor to the open source community. His projects have over 10,000 stars on Github, and are downloaded over 20,000,000 times a month. Haoyi professionally built distributed backend systems, programming languages, high-performance web applications, and much more.

Vaadin 24 in the real world - building the Java Vienna Raffle
TBA

About the Speaker
Sebastian Kühnau ist seit zwei Jahrzehnten Java-Junkie und schon während seines Studiums Vaadin verfallen. Seit 2016 arbeitet er in verschiedenen Tech-Rollen bei Vaadin und unterstützt Kunden, maßgeschneiderte Webanwendungen zu entwickeln. Nebenher ist er zudem auf verschiedenen Events in und mit der Community aktiv.
49 attendees+44
Mon, Jun 2, 2025, 6:00 PM CEST"OpenRewrite in a Nutshell" + "how John started to like TDD (w/ spring boot)"
Needs location
save the date!

Agenda:
18:00 doors open
18:20 welcome
18:30 OpenRewrite in a Nutshell: Scaling Upgrades with Practical Insights - Simon Gartner
19:30 break + networking
19:55 raffle
20:00 how John started to like TDD (instead of hating it) - Nacho Cougil
21:15 networking

OpenRewrite in a Nutshell: Scaling Upgrades with Practical Insights
Schnelle Upgrades, einfache Rezepte:

Was ist OpenRewrite? Kurz & knackig.

Rezepte anwenden: Composite Recipes, dryRun vs. run

Tech-Upgrades: Wenig Downtime, klare Nachvollziehbarkeit (z.B. EAP-8)

Lesende Rezepte: Code-Analyse leicht gemacht

Rezepte schreiben: LSTs, Visitors, Praxisbeispiel

Rezepte wiederverwenden: EAP-8, Quarkus, Spring Microservices

Ideal für effiziente, transparente Software-Upgrades.

About the Speaker:
Simon Gartner - Softwareentwickler @ Gepardec IT Services GmbH.
Simon ist Softwareentwickler mit viel Erfahrung mit Legacy-Code. Er beschäftigt sich in seinen Projekten intensiv mit der Anwendung von OpenRewrite in der Praxis. Sein Fokus liegt bei der automatisierten und reproduzierbaren Durchführung von Migrationen. Simon konnte mehrere Modernisierungsprojekte, wie Frameworkupgrades, effizient und innovativ meisten.

how John started to like TDD (instead of hating it)
Let me share a story about how John (a developer like any other) started to understand (and enjoy) writing Tests before the Production code.

We've all felt an inevitable "tedium" when writing tests, haven't we? If it's boring, if it's complicated or unnecessary? Isn't it? John thought so too, and, as much as he had heard about writing tests before production code, he had never managed to put it into practice, and even when he had tried, John had become even more frustrated at not understanding how to put it into practice outside of a few examples katas 🤷‍♂️

Listen to this story in which I will explain how John went from not understanding Test Driven Development (TDD) to being passionate about it... so much that now he doesn't want to work any other way 😅 ! He must have found some benefits in practising it, right? He says he has more advantages than working in any other way (e.g., you'll find defects earlier, you'll have a faster feedback loop or your code will be easier to refactor), but I'd better explain it to you in the session, right? Ah! And if you think everything will be theoretical, no! Get ready to see code examples with Spring Boot.

PS: Think of John as a random person, as if he was even the speaker of this talk 😉 !

About the Speaker
Nacho Cougil is a software engineer from Barcelona, fan of TDD and XP practices. He has been working with Java and other web technologies before the effect 2000 and had experience in different roles in the IT world now working at Dynatrace writing code to monitor applications. You may probably meet him before as founder of the Barcelona Java Users Group & the Java & JVM Barcelona Conference ( JBCNConf ). He enjoys spending time with his family, playing sports & improving his eXtreme Programming skills.
Nacho is the founder of the Barcelona Java User Group and a Java Champion.
14 attendees+9
Mon, Jun 16, 2025, 6:00 PM CESTJava on AWS Special
TU Wien, Freihaus HS1, Vienna
Joint meetup with AWS Vienna Meetup !

Agenda

18:00 doors open
18:20 welcome
18:30 High performance Serverless Java on AWS - Vadym Kazulkin
19:30 Break
19:55 Raffle
20:00 How to develop, run and optimize Spring Boot 3 application on AWS Lambda - Vadym Kazulkin
21:15 Networking nearby

High performance Serverless Java on AWS
Java is for many years one of the most popular programming languages, but it used to have hard times in the Serverless community. Java is known for its high cold start times and high memory footprint, comparing to other programming languages like Node.js and Python. In this talk I'll look at the general best practices and techniques we can use to decrease memory consumption and cold start times for Java Serverless applications on AWS Lambda including GraalVM (Native Image) and AWS own offering SnapStart based on Firecracker microVM snapshot and restore and CRaC (Coordinated Restore at Checkpoint) runtime hooks. We'll also look into the SnapStart priming techniques which help us increase the Lambda performance and explore how AWS Lambda Profiler for Java can help us identify this potential. We'll also explore the impact of the SnapStart snapshot tiered low-latency cache on the cold start times.

I'll also provide Lambda functions performance (cold and warm start times) benchmarking for:

Deployment package sizes

Lambda memory settings

Java compilation options

Managing Lambda dependencies with Lambda layers

Choice of garbage collection algorithm

Choice of hardware architecture x86 vs arm64

HTTP (a)synchronous clients

How to develop, run and optimize Spring Boot 3 application on AWS Lambda
In this talk I will present and compare several options of how to run Spring Boot 3 application on AWS Lambda using the following framework or tools:

AWS Serverless Java Container

AWS Lambda Web Adapter

Spring Cloud Function

Custom Docker Image.

I'll also discuss strategies how to optimize cold start of such Lambda function with AWS Custom Lambda Runtime based on GraalVM Native Image and AWS own offering SnapStart based on Firecracker microVM snapshot and restore and CRaC (Coordinated Restore at Checkpoint) runtime hooks. Moreover I'll present various (SnapStart) priming techniques to reduce the cold start even further and explain the benefits of the snapshot tiered cache. Is Spring Boot native support of CRaC also a potential optimization? I'll also discuss optimization strategies for the warm start/execution time of the Lambda function.
47 attendees+42