Amsterdam Java User Group

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.

Join in with the latest Amsterdam JUG Meetup at Trifork, Vlaardingenlaan 15, 1062 HM Amsterdam. Upon arrival, take the elevator to the 5th floor where the Amsterdam JUG and the Trifork team will be ready to welcome you.

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.

Notes:

• Complimentary parking is available, request a spot by sending a mail to amsterdamjug@googlegroups.com. Parking spots are limited and not guaranteed, first come, first served. Make sure to submit your request at least one week before the event.
• Vegetarian options: we'll make sure that we cater both to vegetarians and non-vegetarians.

In this meetup, in addition to food, drinks, and networking, you will experience four excellent talks of approximately 30 minutes each:

18:00 - Doors Open (And Food!)
19:00 - 19:35 Talk 1: Joris Kuipers — Runtime Configuration Updates with Sping Boot
19:35 - 20:10 Talk 2: Jeremy Meiss — From DevEx Disaster to Delight: How to Champion a DevEx Revolution in Your Organization
20:10 Short Break
20:15 - 20:50 Talk 3: Raphael de Lio — Count-Min Sketch, Bloom Filter, TopK: Efficient probabilistic data structures
20:50 - 21:25 Talk 4: Jonathan Vila — AI-Powered Productivity in the Development Lifecycle
21:30 - The End

Abstracts

Runtime Configuration Updates with Sping Boot (Joris Kuipers)

Spring Boot applications provide rich abstractions for working with various property sources to configure your applications. Most applications will only read their configuration at startup and require restarts to pick up any changes. However, it doesn’t have to be this way! In this session, we will learn about Spring’s support for dynamically picking up changes in external configurations, so that you don’t need restarts anymore.

From DevEx Disaster to Delight: How to Champion a DevEx Revolution in Your Organization (Jeremy Meiss)

Is your development team struggling with bugs, inefficient tools, and demoralizing processes? Do you often hear your developers expressing their frustration with the deployment process and the codebase? Don't worry, this talk is your ticket to transforming your organization's Developer Experience (DevEx) from a disaster zone to a developer utopia. Join us for a session filled with humor and insights that will equip you with the tools to improve your team's productivity and satisfaction.

Count-Min Sketch, Bloom Filter, TopK: Efficient probabilistic data structures (Raphael de Lio)

A Count-Min Sketch, a Bloom Filter, and a TopK might sound fancy, but they’re just smart ways to work with huge amounts of data using very little memory. In this talk, we’ll explore three powerful probabilistic data structures that trade a bit of accuracy for a lot of speed and scalability. By the end, you’ll see how these tools help you process large data streams without blowing up your memory, and how to apply them in real-world systems where being fast matters more than being perfect.

AI-Powered Productivity in the Development Lifecycle (Jonathan Vila)

In the current software development context, staying updated is essential, and that means using Artificial Intelligence (AI), particularly Code Generative AI. It is changing the way developers work, offering never-seen productivity improvements throughout the entire development life cycle. This talk will go into the practical applications of AI-powered tools and methodologies focused on software development. This talk will showcase practical tools and strategies to integrate AI into your development workflows, increasing productivity and efficiency levels.

Bios

Joris Kuipers. Joris has worked as a hands-on architect and CTO for Trifork for over a decade, in markets as diverse as education, healthcare, news media and government. Before that, he was a trainer and consultant for SpringSource, and he still teaches the occasional Spring training for the Trifork Academy. To his own astonishment, he has been building enterprise applications in Java for 25 years now.

Jeremy Meiss. Jeremy is an international speaker and is currently the Director of DevRel at OneStream Software, previously at CircleCI, Solace, Auth0, and XDA. With almost 30 years in Tech, Jeremy is active in the DevRel and DevOps communities, a co-creator of DevOpsPartyGames.com, and organizer for DevOpsDays Kansas City.

Raphael de Lio. Raphael is a passionate software engineer who loves to think about solutions and ways to improve anything he touches. Currently he serves as a Developer Advocate at Redis, where he combines his love for coding with his enthusiasm for empowering others through education, advocacy, and community engagement.

Jonathan Vila. Jonathan is a Java Champion, member of the Barcelona JUG and cofounder of JBCNConf/DevBcn conference in Barcelona. Currently he works as a Developer Advocate in Java at Sonar (SonarLint,SonarQube), focused on Code Quality & Security.