DubJUG 269 - Geertjan Wielenga and Ivan Sipka
Join us for DubJUG 269 with Dutch Java Champion Geertjan Wielenga and former Oracle Java engineer and OpenJDK author Ivan Sipka
Talk: From CRUD to Durable: Adding Temporal Workflows to the Spring Pet Clinic
Spring Boot applications excel at handling synchronous CRUD operations, but what happens when you need to send appointment reminders days in advance, manage multi-year vaccination schedules, or orchestrate complex payment workflows that must survive server restarts?
In this talk, we'll transform the classic Spring Pet Clinic application by integrating Temporal.io -- the free and open source durable execution platform that makes long-running processes reliable by default.
You'll learn how to:
* Identify which operations benefit from Temporal (and which don't)
* Implement appointment reminders that survive server restarts
* Build multi-year vaccination schedules with Signals and Queries
* Apply the Saga pattern for reliable payment processing
* Test workflows with Spring Boot's testing framework
* Deploy workers separately from your web tier
Geertjan will start with a 5-minute "Hello World" workflow, then progressively build real Pet Clinic features, showing complete code examples you can use in your own applications.
By the end, you'll understand when and how to add Temporal to Spring Boot apps, with practical patterns for background jobs, scheduled reminders, and complex orchestration.
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About Geertjan
Geertjan is a manager, facilitator, and builder of open source developer communities, their social media, technologies, and technical documentation.
Find Geertjan on Linkedin
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Talk: Testing Java with Java: Inside jtreg and the OpenJDK Test Infrastructure
Every Java developer has written tests - but what happens when the thing you need to test is Java itself?
Testing the JDK presents some unusual problems. Tests may need to launch fresh JVMs with specific configurations, verify compilation failures, or behave correctly across different platforms and architectures. This is the world of jtreg, the regression-test harness used for the bulk of OpenJDK testing.
In this talk, Ivan explores how jtreg works, how OpenJDK tests are structured and executed, and why testing a platform requires a different way of thinking about test isolation and execution environments. He'll zoom out from individual tests to the challenge of establishing confidence across tens of thousands of tests and millions of CI executions.
Along the way he'll encounter a surprisingly general testing problem: if every test that ran passed, how do you know that every test that should have run actually did?
No previous OpenJDK experience is required. If you know Java and automated testing, you'll be able to follow along - and you'll leave knowing how to start exploring the JDK's tests yourself.
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About Ivan
Ivan was a principal engineer in Oracle’s Java Platform Group, responsible for release-critical verification and correctness infrastructure for OpenJDK Core Libraries.
He is a JDK Project Author on OpenJDK.
Find Ivan on Linkedin
About the Dublin Java User Group
Since 2006, the Dublin Java User Group, aka DubJUG, has been working with the global Java community to amplify technical knowledge for the benefit of Irish based developers and businesses. It is a resident member of Dublin's TechMeetup.space.
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Our Partners
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Their team of more than 1,700 professionals is headquartered in bustling New York City, with offices in Dublin, Ireland and Aveiro, Portugal, and coworking spaces in the UK, Netherlands, and Australia.
SQUARESPACE ARE HIRING ➡️ Discover more: Website / LinkedIn
Gong is on a mission to empower companies to unlock their full revenue potential. We help everyone in revenue teams to improve productivity, increase predictability, and drive revenue growth by deeply understanding customers and business trends and taking impactful actions.
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Integral Ad Science is a leading global media measurement and optimization platform that delivers the industry’s most actionable data to drive superior results for the world’s largest advertisers, publishers, and media platforms. IAS’s software provides comprehensive and enriched data that ensures ads are seen by real people in safe and suitable environments while improving return on ad spend for advertisers and yield for publishers. Our mission is to be the global benchmark for trust and transparency in digital media quality.
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Stackand.Co enrich the professional lives of Java software professionals - with over 20 years experience in the Irish tech recruitment market, they have helped many great people elevate their careers, and many great companies build their teams.
Perhaps they can do the same for you working with companies like this one?
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FINEOS is a leading provider of core systems for life, accident and health insurers globally with 7 of the 10 largest group life and health carriers in the US as well as 6 of the largest life insurers in Australia. With employees and offices throughout the world, FINEOS continues to scale rapidly, working with innovative progressive insurers in North America, Europe, and Asia Pacific.
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Geertjan on Java is an independent open source Java-oriented advisory, driven by Geertjan Wielenga, the Java Champion involved in several community-driven projects, such as Apache NetBeans and Foojay.io (the place for Friends of OpenJDK).
Are you, and your organisation, looking for insights into...
* How to better communicate with your developer audience;
* How to have more impactful technical documentation;
* How to bring developers onboard into your open source projects;
* How to leverage the international developer community for maximum effect?
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tcube is a low-cost no frills workspace provider located at O'Connell Bridge in Dublin city centre. They provide hot-desks, dedicated co-working desks, office-for-a-day, meeting rooms, and event space.
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