Say yes to.. GraphQL

Circl (Gustav Mahlerplein 1B, 1082 MS Amsterdam)


18:30 – 19:00 Doors open

19:00 – 20:30 Speakers: Gerard & kees

20:30 – 21:30 Drinks & Bites


We will be diving into the world of GraphQL with Gerard. Following to Gerard’s presentation we will be facing a common problem, business demands vs realistic requirements.

Kees Jan will be walking us through his thoughts on how to say “No” in the work field and how to overcome your technical challenges by doing so.

Be prepared to learn something new while enjoying a drink and a bite!


Gerard Klijs

Gerard has been a Software developer for almost 8 years, mainly doing Java backend work for web applications, a couple of times also using Kafka. In his spare time he also writes Rust and Clojure(script). He recently became interested in GraphQL and has made several related open source contributions.GraphQL subscriptions on the JVM

In this talk I will start with a short introduction to GraphQL. As we learn queries and mutations are commonly used in GraphQL, while subscriptions are sometimes not even supported by servers or clients, or not correctly implemented. Because with subscriptions state is stored on the server, they are harder to implements than queries of subscriptions, which are for a big part similar to how REST works. I will share some anecdotes working towards being able to compare the performance of several server implementations on the JVM. Also you will learn some of the limitations of subscriptions and how they might be resolved.


Kees Jan Koster

Kees Jan Koster is Java expert and team coach. Kees Jan speaks often and energetically about people, Java and distributed systems in general. He likes to challenge the audience to ask questions and offer rebuttal to his ideas. Kees Jan previously gave presentations at JavaOne, JCrete, Devoxx, TheServerSide Symposium, ScanDevConf, jPrime, ejug and J-Fall. His JavaOne presentations earned him a JavaOne 2012 Rockstar Award.

“No” is a Working Word

We deal with the word "no" surprisingly often. Kees Jan examines the word "no" in a dialogue with the audience. He looks at the personal aspects of saying and hearing no, but also dives into the things that people deny themselves to force themselves into developing better systems. Participants leave the session with more respect for the word "no". They will say and receive "no" more effectively. Participants are more aware of the role that no plays in their daily work


CIRCL is located next to Amsterdam Zuid Station and is therefore easiest to reach by public transport. If you come by car, there are cheaper parking options near the meetup location. You can park in the streets after "De Boelenlaan" (5/10 minutes' walk) for € 1.40 per hour between 08:00 and 19:00. After 19:00 it is free. Otherwise use one of the many Q-Park options.


We have shaken up the agenda a little: we will have consecutive presentations and will therefore reserve more time to talk to each other. Because we want to prevent unnecessary throwing away of food, we have stopped serving hamburgers. Once started with the Meetup, we will pass on the exact number of participants to the catering, after which we will provide nutritious and healthy bites after the Meetup. Of course accompanied with a (cold) drink. We assure you that you will leave the building without being hungry.

Do you want to eat something in advance? Then you can go to CIRCL for a discount price of € 15 including a drink (normally € 19). You can also visit Julia's, Market 33 or Urban Salad, among others.