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JavaOne vs Devoxx – One Conference to Rule them All!

devoxx vs javaone
Over the last month or so, we attended a great JavaOne, got back home to enjoy the briefest of breaks before enjoying another full week packed with incredibleness, at Devoxx Belgium.

These are the two biggest Java conferences in the world, both within just 3 calendar weeks of each other. Many of us at ZeroTurnaround attended one or both conferences. We sponsored both events as well as presented many sessions, including 7 conference sessions, 2 ignite sessions, 1 nighthacking/vJUG podcast and 2 BoFs – wow, that escalated quickly!

Rather than talk about each conference individually, let’s have some fun and compare the two events, looking at what makes each of them stand out as a top tier conference. After all, it’s not often possible for developers to get to even one of these conferences, let alone both of them! So if you had to pick, which would you go for? We’ll look at cost, sessions, speakers, networking, expo, food, location and more!

Make it rain!

money rain

Firstly the cost, and whether we need to ask our boss to give us a bit of money to attend a conference or whether they really do need to make it rain in order for us to attend. Well, it firstly depends on where you’re located, if you’re in the U.S., a domestic flight to California is going to be a lot cheaper than a transatlantic flight of a minimum 11 hours. Similarly, if you’re in Europe, Devoxx is going to be the cheaper flight option. However, when you get there, hotels are a totally different story! Because JavaOne is colocated with Oracle OpenWorld, over 50,000 Oracle fan boys and girls congregate in San Francisco with the sole duty of nabbing all the hotel rooms and talking about how cool Oracle DB is. As a result, the locals are wise to this and increase hotel prices heavily. We’re not joking here, as much as 2 to 3 times the cost and more, meaning you might have a commute for a hotel further away, or share with another person you might not know well who might even use NetBeans. We stayed at the Hilton, which is the conference hotel. It’s very convenient and costly at the same time– we’re talking $400 USD per night and that’s the earlybird price!  At Devoxx, many will pick a hotel in Antwerp centre as it’s closer to food and beverage dispensing venues. We stayed at the Radisson Blu which is a popular hotel among Devoxx regulars and only a 15-20 min tram ride from the conference. This ran us about $170 USD per night.  Your conference pass will also vary between the two conferences, with JavaOne costing almost 3 times as much as Devoxx at just over $2,000 USD. That’s a significant amount!

Sessions – Content is King!

Both Devoxx and JavaOne provide amazing sessions. As a speaker it’s probably harder to get into Devoxx as there are many more submissions and fewer slots in comparison to JavaOne. After the conference, sessions are made available on YouTube. Well some of the JavaOne sessions make it and this year they were grouped per room, therefore each video was 10 hours, which is a little tough to digest. Devoxx, on the other hand, was really amazing with video content this year and made them available within 24 hours, typically. Voxxed live was also launched at Devoxx, an interesting live-ish stream from Lucy Carey and Mark Hazel, the Voxxed crew. They took a lot of the great content from Devoxx, streaming a number of sessions live, with some additional exclusive interviews and Devoxx day round ups. If I had to pick, I might say the Devoxx sessions are slightly more hardcore in terms of content, and you’re more likely to find more varied speakers, including those from Google! But it’s hard to pick between them, as we’re really looking at the best content across the circuit at both JavaOne and Devoxx.

Keynote wise, JavaOne sucked pretty bad for the opening keynote. It wasn’t overly technical, although that got better when Mark Reinhold and Brian Goetz came out. Sharat Chandler opened it in a very lively and community focused way, but there were little other points that I would mention, which was quite disappointing. The community keynote which was run by the awesome Stephen Chin was extremely entertaining and well thought out (Caveat: I participated in the community keynote). I hope next year Oracle decides to let Stephen lead the main keynote and focus it on developers. Devoxx on the other hand produced a much better keynote with an outstanding session from Professor Lawrence Krauss looking at the origins of life. Kind of puts the last 20 years of Java into a bit of perspective, doesn’t it! Devoxx also had Mark Reinhold give part of the opening keynote, but if you want to hear from more Oracle language designers particularly, you need to be at JavaOne.

A few of our engineers attended Devoxx just for the sessions (European based). Bram Inniger, Product Engineer (Java developer), lists his top three sessions below, and we’ve linked to the replays for your convenience.

7 Ways to hack your brain by Dan Allen

This was an excellent non-Java talk, essentially on how to change your perspective such that you view writing a document as you would writing source code. Dan goes through 7 “tricks” or rather methods which you can use to achieve this. The main idea is to write in pure ASCII (with simple formatting directives using AsciiDoc), allowing you to do cool stuff like commenting, versioning and intelligently diff-ing your text. This talk actually inspired me to pick up Asciidoctor (a rendering utility to export AsciiDoc text into say HTML) and write my summaries and experiences in it! Great job Dan!

Design Patterns in the light of Lambda Expressions by Venkat Subramaniam

An awesome (perhaps the best) talk, so we’ll call this joint top with Dan’s! Venkat described how you can revisit some old clunky and verbose patterns, and make them sleeker and neater with lambdas. A prime example of this was the Decorator pattern, which becomes beautiful simply by just introducing lambdas. Finally, Venkat covered some new patterns that previously were only usable in functional languages.

The Design of a Reliable and Secure Operating System by Andrew Tanenbaum

This was a fantastic talk about the design and direction of Minix. Andrew gave great insight behind the rationale of the system and why it’s so important to be incredibly resilient to failure at a software level. Finally, Andrew also explained the reasoning behind the move towards NetBSD’s userland.

Here are some of Bram’s final tips/takeaways from Devoxx:

  • Multiverses with different physics are perhaps real and can be indirectly observed, though never entered.
  • Lambda’s are awesome!
  • JShell is a pretty damn neat way to write and run some small snippets.
  • Use Asciidoc + Vim to write even awesomer texts in a better way.
  • Re-think latency, where it comes from, how it evolves and scales.
  • Operating Systems are better and safer if their kernel is smaller and written robustly.
  • Do not chase the greatest and latest technology, often it pays very well to just fix your current system in the current stack instead of throwing on X new frameworks.
  • Learn Akka, its actor-messaging-based concurrency models looks absolutely fantastic.
  • HTTP2 is really cool and exciting, we should experiment with setting up Jetty and give it a go.
  • Don’t connect anything unsecurely on the net, expecting no-one to find it, cause it will be found and it will be exploited.

As I mentioned, we also presented at both JavaOne and Devoxx and you can checkout some of our sessions below:

0. JavaOne – Productive Java Development? You Weak-Minded Fool! by Simon Maple


This tongue-in-cheek session takes a look at 10 development tools/projects/products—JIRA, Confluence, Tomcat/TomEE, JRebel, XRebel, Arquillian, JBoss Forge, IntelliJ, Jenkins, and Gradle—explaining what they do and how they “supposedly” help your development practices.

1. JavaOne – Having Fun with Javassist by Anton Arhipov


This session goes through examples of how you can apply Javassist to alter applications’ behavior and do all kind of fun stuff with it. Why is it interesting? Because while you’re trying to do unusual things in Java, you learn much more about the language and the platform itself, and learning about Javassist will actually make you a better Java developer.

2. Devoxx – The Java Council by Simon Maple/Martijn Verburg/Mark Reinhold/Trisha Gee


The Java Council closed out conference season dressed in full Jedi gear.  This is a fun, entertaining and enlightening session where you’ll see blind ignite talks covering 40 years of Java, rockstars on stage playing ‘Just a minute’, interviews with top Java leaders and lighthearted panel discussions.

Speakers and Networking

There’s a track at every conference which is one of the most important to all attendees, but rarely mentioned too much. It’s called the corridor track. This is the track in which you meet like-minded individuals, network with technical leaders, speakers, engage with the community and perhaps even find your next job! As a speaker, JavaOne is seen to be the home of the Java conference. Many speakers when asked would prefer to go to JavaOne, if they could only pick one conference. It really is the one place in the world where for a week you’ll find the highest profile number of Java speakers within a couple square blocks. There are many parties and events throughout the week where you can chat and mingle with these great people. Also there’s a cafe next to the Hilton, well in the road next to the Hilton which is blocked off for the duration of JavaOne! But that’s a great place to hang out and chat with many of the big names at the conference.

Expo halls

From a sponsorship point of view, both conferences are fairly expensive, but you’d expect that given they’re the two largest Java conferences in the world! The JavaOne expo hall is large and very busy. You’ll see people from the JavaOne conference as well as Oracle OpenWorld and will hardly have time to catch breath before talking to the next person during the dedicated hours. The Devoxx expo hall is a lot smaller and you’ll get less space for your booth, but you’ll still talk with a great number of people. The excitement is high and it’s a vibrant room. Attendee scanners are far better at JavaOne. Cost wise, JavaOne is a higher cost, but you get a larger space in which to present. My gut feeling leans towards JavaOne as having the better Expo space, but check out this video as a fun entertaining pit lane walk through the Devoxx expo hall!

Food, Glorious food!

This is where both conferences are left wanting. The JavaOne food is very poor and you’d expect a lot more for the ticket price. There’s a Chipotle a block away so we tended to nip out and get take out instead of the sandwich packs you’re offered at JavaOne. Devoxx is a bit better, but you will get a little bored of soup and baguettes by the end of the week. Ultimately, neither are very good, but at least Devoxx have a sense of humour about it!

So which should you choose?

Well, whichever you decide to go you, you’ll not be disappointed, but if you want an amazing all around experience, I’d pick JavaOne, if you want a similarly high quality conference, with top speakers at a fraction of the cost, go for Devoxx. If you want bad food, you’ll be fine with either! Let us know which conferences you’ve been to and whether your experience differs from ours, we’d love to hear from you in our comments.

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  • Hoyt Summers Pittman III

    You should take a look at DevNexus ( It a large (~1500 people) Java conference in Atlanta. I’m one of the organizers.

  • Simon Maple

    I’ve submitted to it :) Check out the CFP – I’ve never been there but would love to attend!

  • Simon Maple

    Turns out I’ve got two sessions accepted from looking at the DevNexus site, but I just haven’t got the email back yet :)