This morning was kicked off by Katie Gamanji, of American Express and part of the Cloud Native Computing Foundation. The talk was on Kubernetes; there were 23,000 attendees of KubeCon conferences in 2019, and over 2,000 contributors to the project. She introduced the Cloud Native Interface, which is used to ensure that a pod has its own IP which can be routed to via various mechanisms, and the Container Runtime Interface which abstracted away Docker from other engines such as gviosr, containerd etc. Mostly it seemed to be an overview of what Kube does, rather than anything new; for the people who were attending hoping to learn about more than just the basics, I’m not sure what the benefits were.

The rest of the day I spent hosting the Java track, on behalf of Martijn Verburg, who was unable to assume hosting duties due to other committments. I’m very glad that he had those committments, because I had a very enjoyable day, listening to experts in their field as well as playing compere to a captive audience. I’m very much looking forward to being invited back again!

Ben Evans from New Relic was the first speaker in my track, talking about Record and sealed types in Java, which are in an experimental phase. Record objects are data types on steroids; essentially, a data type wich has an automaticaly generated equals, hashCode and toString with the correct properties in a final data structure. Together with sealed types, which are a way of doing inner classes properly, it looks like the various experimental Java projects are really providing the goods.

Andrzej Grzesik, better known as “ags”, talked about the path that Revolut had in mirating to Java 11 over the last year. They moved over to Java 11 as the compile engine and as the runtime engine for all of their apps over the year, following up with various bugs reported against OpenJDK as they wen through, and some of the pitfalls of their experience. The main one seems to be updating all of the dependent libraries and build tools; for example, moving from Gradle v3 to Gradle v4 and v5, a step at a time. They are keen to try keeping up with the latest JDK releases, although their use of Gradle and more specifically Groovy is holding them back from migrating at the moment. Making sure that all of the dependencies worked seemed to be the biggest challenge, though most (non-abandoned) Java libraries work at this stage.

David Delabassee gave an overview from Oracle about how to best drive Java applications inside Docker containers. His examples and slides (to be uploaded later) showed how to use a multi-stage Docker build along with jlink and the --no-man-pages and --no-header-files along with compression to build a custom base image which was about 20% of its original size. He also highlighted using Alpine as a distribution and Musl as a replacement for glibc, but noted this wasn’t officially supported; project portola aims to provide a means to do this in the future. By using AppCDS he was able to shrink the launch time down further, and talked about the evolution of Docker and docker rootless along with a podman blog talking more about enabling this functionality.

Emily Jiang gave a talk and live demo of how to build a 12-factor app with Open Liberty and MicroProfile. The demo code is available on GitHub and since it was a live demo, the screencast from InfoQ will have a lot more detail. In essence, Emily demonstrated having two services, connecting via localhost, to be run inside different Kubernetes pods and with redundant services, and used asynchronous calls to be able to route around delays or failures in the underlying service implementations. One to watch carefully on the replays, I think.

The day was rounded off nicely by James (Jim) Gough whom I’ve had the pleasure of working with commercially before. He gave a talk on how GraalVM executes code, and showed a number of demonstrations of how Graal can eecute code that has been compiled using the Java compiler, by debugging through how the JDK’s JIT (in the form of Graal) works. He also demonstrated the jaotc tool for compiling Java code ahead of time for faster startup and lower memory footprint. I had had a prior audience for this talk, and so almost everything went to plan in this presentation – with the exception of the QCon sign falling off the podium by the end. Oh well, it had been a long day …

This brought to the end my 12th? QCon London. I don’t think I’ve been to all 14, but I have certainly been to most of them over the past years, and all in all, it’s just as great as ever. Obviously this year was a little ‘special’ due to all the changes in place, but I thought that the staff (both at QCon and also at the QEII conference centre itself) handled everything marveously. I can’t wait to be back again this time next year, either as an attendee, speaker or track host!