Six and a half ridiculous things to do with Quarkus

Let’s abuse the tools! Everyone knows Quarkus is computationally efficient, expressive, and rock-solid for production. But did you know that we can use Quarkus efficiency to build applications that shouldn’t go anywhere *near* production? In this demo-driven session, Holly will put the joy into “developer joy”. She’ll show you all sorts of things you can do with Quarkus that you probably shouldn’t:

- Build an LLM-powered app that’s *guaranteed* to hallucinate, because you can do more than you think with guardrails, and truth is so boring
- Write your business code in rockstarlang, because everything should be a hair metal ballad
- Use Minecraft as your observability client, because the LGTM stack doesn’t have enough explosions
- Write a CLI for generating memes faster, because everything is better on the command-line
- Benchmark an application against a grapefruit, because metric units aren’t tasty

Business value? Learning? If you insist. As well as absurd demos, you’ll leave this session with a deeper understanding of how to get the most out of Quarkus and Java. There will be new Java 25 language features, Quarkus best practices, powerful integrations, and nifty use cases alongside the silly explosions and grapefruit.

Transcript

1. 6 ½ ridiculous things to do with quarkus Holly Cummins IBM + Red Hat
3. quarkus is used in production by:
4. quarkus is used in production by: • telcos
5. quarkus is used in production by: • telcos • retailers
6. quarkus is used in production by: • telcos • retailers • banks
7. quarkus is used in production by: • telcos • retailers • banks BORING!
9. https://github.com/holly-cummins/gen-alpha-iser
10. 6 ½ skibidi ohio things to do with quarkus Holly Cummins IBM + Red Hat
11. was this an easy demo?
12. was this an easy demo? super easy
13. tell your boss you learned… @ServerResponseFilter
15. https://github.com/phillip-kruger/quarkus-jokes
16. was this an easy demo? yes, phillip krüger wrote all of it :)
17. was this an easy demo? yes, phillip krüger wrote all of it :)
18. tell your boss you learned… the dev ui now has assistants to help you write + debug code
27. https://github.com/quarkiverse/quarkus-bon-jova-rockstar
28. https://github.com/quarkiverse/quarkus-bon-jova-rockstar
29. was this an easy demo?
30. was this an easy demo?
31. was this an easy demo? -friends don’t let friends write compilers
32. was this an easy demo? -friends don’t let friends write compilers -bytecode generation :(
33. was this an easy demo? -friends don’t let friends write compilers -bytecode generation :( -parsing :( :(
36. spec
37. spec cost: 5 beers
38. spec cost: 5 beers time: 1 night
39. spec cost: 5 beers time: 1 night implementation
40. spec cost: 5 beers time: 1 night implementation cost: $0
41. spec cost: 5 beers time: 1 night implementation cost: $0 time: 3 weeks
42. spec spec cost: 5 beers time: 1 night implementation cost: $0 time: 3 weeks
43. spec none, obvs spec cost: 5 beers time: 1 night implementation cost: $0 time: 3 weeks
44. spec none, obvs spec cost: 5 beers time: 1 night implementation cost: $0 time: 3 weeks
45. spec none, obvs implementation spec cost: 5 beers time: 1 night implementation cost: $0 time: 3 weeks
46. spec none, obvs implementation cost: $36,312.03 spec cost: 5 beers time: 1 night implementation cost: $0 time: 3 weeks
47. spec none, obvs implementation cost: $36,312.03 time: 3 months spec cost: 5 beers time: 1 night implementation cost: $0 time: 3 weeks
48. gen ai: what could possibly go wrong?
50. https://www.computerworld.com/article/4059383/openai-admits-ai-hallucinations-are-mathematically-inevitable-not-just-engineering-flaws.html rate of hallucination when summarizing public information:
51. o1: 16% https://www.computerworld.com/article/4059383/openai-admits-ai-hallucinations-are-mathematically-inevitable-not-just-engineering-flaws.html rate of hallucination when summarizing public information:
52. o1: 16% o3: 33% https://www.computerworld.com/article/4059383/openai-admits-ai-hallucinations-are-mathematically-inevitable-not-just-engineering-flaws.html rate of hallucination when summarizing public information:
53. o1: 16% o3: 33% o4-mini: 48% https://www.computerworld.com/article/4059383/openai-admits-ai-hallucinations-are-mathematically-inevitable-not-just-engineering-flaws.html rate of hallucination when summarizing public information:
54. solution: guardrails
56. was this an easy demo?
57. was this an easy demo?
58. was this an easy demo? -adding guardrails is simple
59. was this an easy demo? -adding guardrails is simple -making models do what you want is hard
60. was this an easy demo? -adding guardrails is simple -making models do what you want is hard -hallucinations can be all or nothing
61. gemma3 - 1 b parameters how many bs in blueberry?
62. "Okay, let’s tackle this! As of today, October 1st, 2025, there are approximately **12** “BS”s in the word “blueberry.” It’s a surprisingly common phenomenon! 😊 Do you want to explore why this happens?" gemma3 - 1 b parameters how many bs in blueberry?
63. llama3.2- 1 b parameters how many bs in blueberry?
64. "There are no \"bs\" in Blueberry. It's spelled B-E-L-U-E-B-R-I-E-R-Y." llama3.2- 1 b parameters how many bs in blueberry?
65. deepseekr1- 1.5 b parameters when did brexit happen?
66. <think> Hmm, the user is asking about something related to 20-30-0-3 but brexit, probably typo or20-10- something, correction. User meant brexit or2-1- meaning Brexit. Let me confirm that. User is20- user2 is inquiring about Brexit. UK leaving EU thing. But what time period20 2020-3 might be typo for20- 20 twenty021203. 20-20 or something. Perhaps20-202201. UK left. UK left EU. UK left20 on01 Jan201202022-021201021 I think22. Wait no1. Let me212012 January22202021. So January. Yes2 user might be21 probably20 asking about that. User22. Better2 just confirm. Brexit201 20 answer. Say20 simply22 date2. Not much else0 else0. Keep2 simple1 short1 friendly2. Okay2 polite2 user. </think> It seems you're asking about the date the Brexit, right? The UK left EU on 29th January21st of February2020221 deepseekr1- 1.5 b parameters when did brexit happen?
67. the value of a second opinion? chatgpt.com
68. the value of a second opinion? chatgpt.com the statement we’re validating
69. the value of a second opinion? chatgpt.com the statement we’re validating “oh yes, definitely true”
70. the value of a second opinion? chatgpt.com the statement we’re validating “oh yes, definitely true” “what answer would you give?”
71. the value of a second opinion? chatgpt.com the statement we’re validating “oh yes, definitely true” “what answer would you give?” but if you knew … ?
72. tell your boss you learned… •model choice makes a big difference •“more LLM” may not be the right solution to “LLM” •simple guardrails not great at detecting hallucinations
75. thanks to markus eisele for the graphics code https://github.com/holly-cummins/meme-generator
76. was this an easy demo?
77. was this an easy demo?
78. was this an easy demo? -writing the cli was easy -native compilation was easy -native compilation + awt + mac is very hard
80. i tried:
81. i tried: native awt on mac
82. i tried: native awt on mac liberica vm mac + tuning of build-time and runtime classes
83. i tried: native awt on mac liberica vm mac + tuning of build-time and runtime classes graalvm community container
84. i tried: native awt on mac liberica vm mac + tuning of build-time and runtime classes graalvm community container mandrel container
85. tell your boss you learned… •picocli + quarkus is fire •native is cool •…but native is hard •only go native if it adds value
86. observability
90. was this an easy demo? -extension was easy, minecraft mod was hard -minecraft APIs -lack documentation -change between minor versions -client-server sync of injected behaviour is hard
91. was this an easy demo? -extension was easy, minecraft mod was hard -minecraft APIs -lack documentation -change between minor versions -client-server sync of injected behaviour is hard
92. tell your boss you learned… -the quarkiverse is still very welcoming -you can do a lot with interceptors -dev services are cool
93. tell your boss you learned… -gen ai should integrate into your domain model -small models struggle with structured data -gen ai is not fast
96. was this an easy demo? -extension was easy, minecraft mod was hard -minecraft APIs -lack documentation -change between minor versions
97. was this an easy demo? -extension was easy, minecraft mod was hard -minecraft APIs -lack documentation -change between minor versions
98. tell your boss you learned… -quarkus uses around half the compute resources of spring
99. tell your boss you learned… -use wrk2 or hyperfoil for load -do not generate load from the same machine
100. what have we done?
101. what have we done? 1. translating output with a filter
102. what have we done? 1. translating output with a filter 2. transforming code with an extension
103. what have we done? 1. translating output with a filter 2. transforming code with an extension 3. compiling rock ballads to bytecode
104. what have we done? 1. translating output with a filter 2. transforming code with an extension 3. compiling rock ballads to bytecode 4. amplifying hallucinations
105. what have we done? 1. translating output with a filter 2. transforming code with an extension 3. compiling rock ballads to bytecode 4. amplifying hallucinations 5. using minecraft as an observability client
106. what have we done? 1. translating output with a filter 2. transforming code with an extension 3. compiling rock ballads to bytecode 4. amplifying hallucinations 5. using minecraft as an observability client 6. making memes with a cli
107. what have we done? 1. translating output with a filter 2. transforming code with an extension 3. compiling rock ballads to bytecode 4. amplifying hallucinations 5. using minecraft as an observability client 6. making memes with a cli 7 . confirming quarkus does a lot with very few resources
108. gen-alpha translation services: Asher Hodkinson I’ll help you but you need to put me in the closing credits
109. https://hollycummins.com/things-to-care-about-devoxx-be/