Amsterdam Java User Group

Join in with the latest Amsterdam JUG Meetup at Sociale Verzekeringsbank (SVB), Van Heuven Goedhartlaan 1, 1181 KJ Amstelveen, Nederland.

Important notes:

• Bring your passport, or ID card, for identification, otherwise you will not be let in.
• When you register here on the Meetup page, please make sure to include your first and lastname. (If you have not done so, please drop a mail to amsterdamjug@googlegroups.com with your first and lastname.)
• There is free parking, if you send your license plate number to amsterdamjug@googlegroups.com.
• Vegetarian options will be available.
• Signage will be clear, apologies to those who got lost at previous meetups.

For more details and discussions on the below, go to bit.ly/join-foojay-slack to join the Friends of OpenJDK (Foojay.io) Slack and use the #jug-amsterdam channel for conversations related to the below.

In this meetup, in addition to food, drinks, and networking, you will experience the following program and talks:

17:45 - 18:00: Doors Open
18:00 - 18:45: Food (Asian buffet)
18:45 - 19:30 Talk 1: Increasing Portability in a Containerized World (Spoiler: It’s More Than Just Docker)—Jeffrey Janssen (SVB)
19:30 - 20:00 Talk 2: Level Up Your Java Streams with Gatherers—Hinse ter Schuur (SDB Professionals)
20:00 Short Break
20:15 - 20:45 Talk 3: Be More Productive with IntelliJ IDEA—Marit van Dijk (JetBrains)
20:45 - 21:00 Exit

Abstracts

Increasing Portability in a Containerized World (Spoiler: It’s More Than Just Docker)—Jeffrey Janssen (SVB)

When we talk about portability, containers often steal the spotlight. But what happens when you’re migrating an entire DevOps process—from on-prem OpenShift on bare metal and CI/CD pipelines to the cloud? It’s not just about containers: it's about transforming the way your Java applications are built, deployed, and scaled in a cloud-native world.

In this session, I’ll take you through our journey of moving everything to the cloud: setting up cloud-based CI/CD pipelines, using OpenShift in Azure, and automating everything with ArgoCD based on GitOps principles. This talk focuses on the DevOps techniques surrounding Java applications—how to make them portable, how to integrate them into cloud environments, and how to automate the deployment process for faster, more scalable solutions.

If you're a Java developer looking to understand how cloud-native DevOps practices can help automate your workflows and scale your applications, this session is for you.

Level Up Your Java Streams with Gatherers—Hinse ter Schuur (SDB Professionals)

Since Java 8, the Stream API has been a valuable tool for Java developers. However, our hunt for better solutions has often left us wanting more. Until now, we could only use the standard provided intermediate operations on streams, like map, filter, and flatMap.

Enter Java 24's new Stream Gatherers, which allow for adding custom intermediate operations to our streams.

In this session, you'll learn what Gatherers are, where they shine, and how you can implement your own. By the end of the session, you'll be fully equipped to use this powerful new feature in your day-to-day work.

Be More Productive with IntelliJ IDEA—Marit van Dijk (JetBrains)

IntelliJ IDEA is designed to help developers stay in the flow while working. It has a powerful editor, refactorings, navigation, and all kinds of smart features to help you write and read code. At the same time, it is jam packed with tools professional developers need, like Maven, Gradle, Spring, Git, Databases, Test tools and more. And did I mention a fantastic debugger?

In this talk, you will see how IntelliJ IDEA supports your workflow without having to leave the IDE, and learn how you can be a happier and more productive developer.

Join in with the latest Amsterdam JUG Meetup at Elastic, Keizersgracht 281 · Amsterdam, NH.

Note: This meetup is being held together with the Elactic Netherlands User Group (making available a limit of 50 attendees each), who also have a registration page for this event, so if you have already registered at their meetup page (here), there's no need to register again here, i.e., don't register here if you're already registered there.

For more details and discussions on the below, go to bit.ly/join-foojay-slack to join the Friends of OpenJDK (Foojay.io) Slack and use the #jug-amsterdam channel for conversations related to the below.

In this meetup, in addition to food, drinks, and networking, you will experience the following program and talks:

17.45: Doors open
18.00: "One Does Not Simply Query a Stream"—Viktor Gamov, Principal Developer Advocate, Confluent
18.45: "ES|QL FTW!"—Piotr Przybyl, Senior Developer Advocate, Elastic
19.30: Networking, food with drinks
20.00: Wrap up

Abstracts

"One Does Not Simply Query a Stream"—Viktor Gamov, Principal Developer Advocate, Confluent

Streaming data with Apache Kafka has become the backbone of modern applications. While streams are ideal for continuous data flow, they lack built-in querying capabilities. Unlike databases with indexed lookups, Kafka’s append-only logs are designed for high-throughput processing—not for on-demand queries. This necessitates additional infrastructure to query streaming data effectively.

Traditional approaches replicate stream data into external stores: relational databases like PostgreSQL for operational queries, object storage like S3 accessed via Flink, Spark, or Trino for analytics, and Elasticsearch for full-text search and log analytics. Each serves a purpose—but they also introduce silos, schema mismatches, freshness issues, and complex ETL pipelines that increase system fragility.

In this session, we’ll explore solutions that aim to unify operational, analytical, and search workloads across real-time data. We'll demonstrate the following:

• stream processing with Kafka Streams, Apache Flink, and SQL engines
• real-time analytics with Apache Pinot and ClickHouse
• search capabilities with Elasticsearch
• modern lakehouse approaches using Apache Iceberg with Tableflow to represent Kafka topics as queryable tables

While there's no one-size-fits-all solution, understanding the tools and trade-offs will help you design more robust and flexible architectures.

"ES|QL FTW!"—Piotr Przybyl, Senior Developer Advocate, Elastic

NoSQL for years was associated with JSON. The thing is: if you're a hardcore backend Java developer, JSON, YAML, and other data formats might not feel native to you. Also, if you were ears-deep into debugging a query from Java code, sending the same request for visualization in Kibana using KQL wasn't trivial.

Meet ES|QL: Elasticsearch's new query language, being at first glance a mixture of SQL and... Bash ;-) Works the same in Java and Kibana (and other programming languages too!) Additionally, by leveraging Project Valhalla and vector operations, ES|QL can achieve performance improvements over previous solutions.

If you're eager to investigate the options of the ES|QL and how it makes your life easier (while also giving a feel of being a SQL DB), this talk is for you.