JHUG meetup October 30th 2018

Java is famous for the uptime of applications and our meetup certainly meets the challenge. The October meetup was held last Tuesday and it was very interesting.

The place was the premises of Eurobank one of the largest Greek banks. Eurobank provided their auditorium, a very large one indeed, but our meetup scales well and there were about 100 attendants that made the large room seem smaller. Our hosts also provided the treats: coffee, beer and pizzas, the standard essential nutrition for software engineers.

Kostis Kapelonis welcomed the attendands on behalf of JHUG. After a quick recap of the schedule he made a call for talks for our following meetups reminding one of the principles of our group: It is not necessary to be an expert to give a talk, all is needed is a little curiosity and work to tackle a topic and a lot of good will to share your findings. Most, if not all, speakers of JHUG are not professional speakers but give talks for the shake and fun of it and this has worked well so far.

Mr Philip Anastasakos introduced Eurobank to us. The bank is committed to all things digital providing a large portfolio of digital services to their customers. But for Eurobank digital also means Java as they are both committed and satisfied from the platform. The IT department of the bank has great plans for 2019 and they are working to create a talent pool to help them achieve their goals. Anyone interested in participating can contact Philip via LinkedIn.

And now the major part, the talks.

Getting (a bit) familiar with Data Science – Ioannis FoukarakisSlides

The first talk was by Ioannis Foukarakis a senior engineer at Yilu . He decided to make a introductory talk to the topic to lay the foundations for it. He explained what is data science, what is not data science, common traps and pitfalls. Then he presented an application, a spam filter, and how he attacked the problem as a data scientist and the solution he devised using Apache Spark. Finally he concluded with some clarifications about the vocabulary of the field like machine learning, supervised – unsupervised learning, deep learning etc. It was a very good and well paced talk that certainly answered many questions about data science.

This talk was exactly what JHUG is about: Share knowledge, good will and challenges.

Java is still free – Spyros AnastasopoulosSlides

The second talk was a lightning one and lasted about 10 minutes including the Q&A sessions. The topic was the new commercial license of the JDK by Oracle and the confusion and controversy it has generated among the users. The talk was like a journalist’s article gathering facts from many sources on the internet. The slides contain the most important references and the reader should consult them to form his own opinion on the issue. For those who prefer to see front pages and not dig deep in the news just one hint: Follow the AdoptJDK project.

Lightning talks are not frequent in JHUG but this need not be the case. A lightning talk is very easy to prepare and deliver. Many large conferences have sessions for lightning talks and they devote a window of an hour to 5-6 of them. It would be interesting to try something like that in a following JHUG meetup. The submission window for the next meetup is open and accepts lightning talks.

Notes on Java security – Dimitris GlynosSlides

The third and final talk was about Java security. It was delivered by Dimitris Glynos of Census Labs a company that provides IT security services. One of their services is source code audits and he presented to us some of his experience with Java. He presented security holes originated by bad exception handling, race conditions, insecure APIs, insecure serialization of objects and insecure third party components. He introduced each case as a Q&A game with the audience and then presented the detail of the problem and potential solutions. Both the pace of the talk and the quality of the material made this talk very appealing to the audience. The slides are also very well written and will repay study.

Security is a bit weird. You think you have a secure system, then someone shows you a hole and even it is in front of your eyes you still can’t believe how such a thing was introduced in the code base. That talk helped us to start looking not just for bugs but for security holes. The difference is not subtle, it is important:

  • Bug: A user does something unexpected and crashes your application
  • Hole: A user does something unexpected and it is no longer your application


Of course besides the talks there was a lot of networking between our members, old and new, and a lot of ideas exchanged. The positive energy that such meetups give to the attendants is enormous.

In this meet up we also made a draw for one IntelliJ license a gentle offer of Jetbrains. We also shared some sticker with our logo a gentle offer of Thomas Pliakas.

At the meetup page, here, there is a photo gallery from the meetup.

We are looking forward to our next meetup on 3 December. Details will be announced in our official channels. Stay tuned.

Finally we would like again to thank SoftConf and Voxxed Days Athens for the donation of a wireless Shure microphone that we use to record the questions of the audience. Such acts are a great boost for local meetups.


You can learn news about JHUG, participate and exchange ideas and feedback via our channels:


News about meetups and other events are published in all these channels but the interesting discussions are on slack. If you are not there, consider joining.

See you at the next meetup. Until then keep coding.

JHUG event – May 2017

Η εταιρία Agile Actors θα μας φιλοξενήσει στις 12 Μαΐου για το επόμενο meetup (RSVP εδώ)

Οι ομιλίες:

• A Gentle Introduction to Cassandra Database – part 2 (Πέτρος Κακλαμάνης)

Μία απο τις πιο γνωστές NoSQL Βάσεις Δεδομένων είναι η Cassandra DB, δημοφιλής για τα εξής χαρακτηριστικά της: availabilty, scalability, και predictable performance. Σε αυτήν τη δεύτερη παρουσίαση θα εστιάσουμε στους μηχανισμούς της για Lightweight Transactions, καθώς και σε τεχνικές μοντελοποιήσης δεδομένων για αυτήν (Data Modeling, and Schema Design) με παραδείγματα σε CQL και Java. Μπορείτε να παρακολουθήσετε το πρώτο μέρος της παρουσίασης εδώ.

• Reactive Extensions for Java (Σπύρος Αναστασόπουλος)

Οι reactive επεκτάσεις για java είναι ένα ακόμα ένα σύγχρονο topic/buzzword. Σύμφωνα με το site, είναι ένα “API for asynchronous programming with observable streams”, ένας ορισμός πολύ γενικός και διφορούμενος καθώς ισχύει για όλα τα frameworks που περιέχουν έστω και εν μέρη την έννοια του data pipeline. Σε αυτή την εισαγωγή θα παρουσιαστεί η υλοποίηση του παραπάνω spec σε java (βλέπε εδώ) μαζί με τυπικές αρχιτεκτονικές και παραδείγματα χρήσης. Η ομιλία είναι εισαγωγική και δεν προυποθέτει εξοικείωση με το domain.

Συμβουλευτείτε το χάρτη.


• 18.30 – Προσέλευση/ έλεγχος εισόδου

• 18.45 – 19.45 Ομιλία για Apache Cassandra

• 19.45 – 20.00 – Ομιλία χορηγού

• 20:00 – 20:30 Πίτσα/πηγαδάκια/networking

• 20:30 – 21.30 Ομιλία για Reactive Extensions

Για λόγους ασφαλείας, παρακαλούμε κρατάτε μία ταυτότητα για την εισοδο.

Σας περιμένουμε!

(Είσοδος ελευθερη)