Archive for the ‘opinion’ Category

Work on profit-maximizing IT systems – No thanks

July 24, 2017 Leave a comment

Recently I was contacted by a well-meaning IT recruiter (name omitted for privacy reasons) and explained why I don’t work on financial trading systems anymore:

The request

Hi Oliver,

I came across your profile in my connections this morning and I was keen to reach out to you.

I can see your current experience working with Java, I am currently working on some Core Java opportunities working on the new development of a real-time trading platform.

This opportunity would allow you to work with the latest Java technologies as well as giving the opportunity to learn Scala.

Please let me know when the best date and time to get hold of you would be so we can discuss?

Kind regards,

The response

Hello XXXX,

Is it a trading platform in the financial services sector (i.e. banking)?

If so then I have to politely decline. I have worked on trading systems for a large investment bank in the past. My role was Senior Developer / Technical Lead.

But I decided that I didn’t want to spend my limited life-time helping Wall Street traders or other folks whose only business is to make more money for themselves and their (usually already wealthy) investors.

I currently work on systems that support the Canadian Search & Rescue helicopter fleet. Rescuing people’s lives or health is a cause I feel good about and that motivates me.

Please feel free to contact me again if you come across job openings that contribute to the common good.

Oliver Doepner

Categories: coding, opinion Tags: , ,

Simplest Dependency Injection

January 17, 2017 Leave a comment


Note to self: If you create a Java application and think you need DI but not AOP, then do not automatically reach for containers like Spring, CDI, Guice. Just do all construction and wiring in the standard main method.


My favorite Free/Open Source Intellij Community plugins

July 28, 2016 Leave a comment

“Lidar News” publishes uninformed (L)GPL rant

June 16, 2015 4 comments

In its “Random Points” column, the June 2015 issue (Vol.5 #4) of Lidar News, recently renamed LidarMag, contains an opinion piece called “Open Source Mania” (PDF) by Lewis Graham, a director of the board with ASPRS, the organization that defines the LAS file format.

The article contains grains of interesting and potentially relevant comments on the LGPL, but without properly spelling things out: The LGPL – if not amended with a static linking exception as in the LASzip license – has “copyleft” implications when the library code is statically linked, which is somewhat similar to but not as strict as the “strong copyleft” nature of the GPL. I recommend reading the LGPL section of the “Copyleft Guide” or a good article on the Open Source “risks” and considerations during corporate acquisitions and mergers.

Having said that, Lewis Graham’s piece contains many inaccuracies and unfair judgements:

1) The author underhandedly attacks Martin Isenburg’s broadly supported attempts to have the LGPL-licensed de-facto standard LASzip accepted as an Open Standard and then goes into a rant about the GPL, while lumping both licenses together as “viral”. The LGPL – not the GPL – explicitly allows the use as dynamically linked library without any licensing impact on the main program. Combining the attack on the LASzip community with a rant against GPL while ignoring the main difference between LGPL and GPL is unfair to say the least.

Lewis also fails to mention that the LASzip license is actually LGPL with an additional clause that explicitly allows even static linking without licensing impact on the main program.

2) He falsely claims that “Open Source” was never defined but fails to mention the Open Source Initiative (OSI) who coined the term and provided exactly that Open Source definition.

3) The article misleadingly mentions the Free Software Foundation as the “anchor organization” of Open Source, repeats the old misunderstanding that “Free Software” should not cost money and fails to mention the “Free Software” definition by the FSF.

4) The author spreads long debunked FUD (fear, uncertainty, doubt) about the GPL, claiming that all “code [that] touches GPL code in any manner [..] is now GPL”. In particular he makes false claims that the following uses of GPL code would be “viral”:

  • Executing a GPL licensed program from a script via process execution (“Unix fork”) explicitly does not impose any licensing restrictions on that script, as per GPL FAQ
  • Derived works that incorporate GPL licensed code, do not automatically become GPL licensed. Only when the derived work is distributed the following applies (quoting GPLv2, section 6): “Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions.”

5) The author repeatedly refers to an “Open Software Foundation”. He seems to confuse or conflate Open Source Initiative (OSI) and Free Software Foundation (FSF). The actual “Open Software Foundation” – later merged into “The Open Group” – has not much to do with either OSI, FSF or software licenses.

6) The author keeps calling the GPL “toxic”, while in fact the GPL is a widely known and court-proven license in the software industry that many companies use successfully as part of their business models, for example Redhat (Linux), Oracle (MySQL), etc. Especially Dual Licensing based business models actually benefit from the relatively restrictive nature of the GPL.

7) The author praises the MIT license as “reasonable” because of its permissive nature (i.e. not imposing any significant licensing restrictions on derived works). As he makes that judgement he takes only the perspective of companies that want to use Open Source libraries in their proprietary closed-source products. He ignores the perspective of Open Source developers, communities and companies who want to protect their work from embrace and extend and other hostile take-over strategies and deliberately use copyleft licenses like the GPL to protect their software.

8) Overall, the author fails to accept that it is the copyright holders freedom to chose a license that suits their needs and intentions.

OSGeo Open Letter for Open Formats of LiDAR data

April 16, 2015 1 comment

A widely unnoticed revolution is going on in the field of capturing landscapes for mapping and other geographic purposes, and it is laser based:

LiDAR is the technology that uses lasers on small airplanes to literally scan in whole geographic regions and turns them into 3d point clouds. In many ways, especially for high-resolution 3D elevation data, LiDAR is already replacing traditional satellite based approaches, and enables a plethora of applications in many fields of science and business.

So far, the de-facto standard file formats for storing these “point clouds” are LAS and its compressed variant LASzip (Open Source, LGPL, developed by the German software engineering firm rapidlasso).

But recently ESRI, the market leader for Geographic Information System (GIS) software, has stepped into the arena with a closed source compression format, deceptively called “Optimized LAS” (aka *.zlas), and is positioning it as a direct competitor to the widely used Open Source LASzip format.

The closed-ness of the ESRI file format and the resulting fragmentation of the LiDAR community and its data stores, has now lead to a concerted “Open Letter of the Need for Open Standards in LiDAR“, signed by many representatives from LiDAR related companies, research institutions and the wider geo-informatics community.

I hope that this is a step towards protecting the LAS format from “hostile takeover” by ESRI and I have added my name to the signature list today.

In the very least the Open Letter will raise awareness of the importance of Open Standards and Open Source in the essential field of geographic data, data about our planet, about the world we all live in, which should be Open Data, available to all via Open Standards via Open Source tools, not locked away in vendor-proprietary binary formats that can only be read and processed using that single vendor’s tools.

Categories: opinion Tags: , , , ,

JBoss Undertow is pulling me in … :o)

March 19, 2015 1 comment

I am very impressed as I am trying out the various code examples for Undertow, a kick-ass, light-weight yet powerful, ultra-easy-to-embed HTTP and Java Servlet engine.

One of my side projects requires an embeddable yet feature-complete Java HTTP engine with low memory footprint and a simple straightforward API. I dismissed Tomcat, briefly considered Jetty, found Winstone too old and unmaintained, simpleframework not well-enough documented, vert.x and netty a little too much for my purposes and/or too complicated, so that a few weeks ago I had actually started to clone and refactor NanoHttpd.

The NanoHttpd refactoring was a great learning experience, but it certainly felt like I was reinventing the wheel in the form of a cute and mobile but slightly rusty foldable unicycle. ;o) – no offense please, nanohttpd developers

Then I found out about Undertow. The author Stuart Douglas is now officially my hero. What an awesome job he is doing! The server meets all of the above mentioned requirements and is apparently also comparatively fast. No wonder it is the HTTP engine used by Wildfly, the new JBoss AS.

Anyway, if you want to try yourself, I’d go with version 1.1 final at this time, i.e. this in your Maven pom.xml:


I decided to pretty much ignore the documentation section of the website for now, as it is still for version 1.0 and the API has changed – improved, I guess – since then. It seems to me, that at this point the core code itself and the usage examples are the best documentation for version 1.1. Both are Maven modules of the undertow github project.

By the way, if you are wondering why the project has no issues section on github: The issue tracking is done in the JBoss Jira.

How to report profiles of LinkedIn spammers

March 15, 2015 Leave a comment

If you use LinkedIn discussion lists – like the “Java Developers” one that I frequently participate in – you might have seen posts about “Fast Loans” and other annoying commercial messages that are unsolicited, way off-topic and commonly referred to as spam.

A first step is to point out to the poster, typically by simply commenting on their posting, that each LinkedIn group has a “Promotions” section and kindly ask them to delete the spam and to select the “Promotions” category accordingly in the future. Sometimes this friendly approach actually works.

LinkedIn has an official guideline for “Flagging an Inappropriate Discussion or Comment in a Group“, but often the recommended flagging of individual posts leads to no visible change and quickly gets tiresome, since it will only temporarily hide the flagged content and – in my experience -leads to no repercussions for the spammer themselves.

If you are lucky, your LinkedIn group has active owners who you can contact and they might block the spammer and/or even lock down the group to “members only”. But unfortunately, group owners often do not have the time or motivation to do this kind of policing.

So if a spammer ignores your friendly requests and continues to fill your favorite discussion group with garbage and you have run out of other options, consider reporting their LinkedIn profile like this:

- Go to the LinkedIn profile of the spammer (by clicking on their name)
- Use the dropdown arrow of the blue "Send [Firstname] InMail" button
- Select "Block or report"
- Click the option "Report [Firstname Lastname] so that"
- For "Flag profile as" select "other"
- In "Details" put this, replace LINKEDIN_GROUP_NAME accordingly:

This profile has been repeatedly used to post unsolicited, completely off-topic, commercial messages on LinkedIn groups like ‘[LINKEDIN_GROUP_NAME]’. The owner of the profile has so far ignored all requests to stop the spamming. Please take appropriate actions.

- Then click "Continue" button on the bottom
- Agree to the prompt "Are you sure you want to report [Firstname Lastname]?"

Finally you should see a notification:

“Thank you. The profile has been flagged for review by LinkedIn Customer Service.”

Optionally, copy that notification text and paste it into a comment / reply to the spam posting that caused you to report the person. That way the spammer will notice that (and how many) people reported them.

Categories: opinion Tags: , ,

Grouping Java skills by categories

November 14, 2014 5 comments

I would like to group skill items from typical Java developer resumes – aka CVs – in a somewhat standardized way. See this jsfiddle for some work-in-progress.

I came up with the primary and secondary categories listed below, each with some sample items.

Your feedback is highly appreciated. Please comment on this blog post.

  • Java features and APIs:
    • Configurable JVM feature (Garbage collection, Remote debugging, JMX, etc)
    • Java language feature (Generics, Threads, Annotations, Enums, Lambdas, …)
    • Java SE API (Collections, Date/Time, NIO, java.util.concurrent, …)
    • Java EE API (EJB, JMS, JPA, JSF, JSP, …)
    • Java SE UI (Swing, JavaFX, WebStart, Applets, …)
    • 3rd party Open Source web frameworks (Struts, Wicket, Spring MVC, …)
    • Other 3rd party Open Source framework (Spring, Hibernate, …)
    • Closed-source vendor technology (Java based but no JSR)
  • Java Tools/Servers:
    • Application Servers (Websphere, Weblogic, JBoss, Glassfish, Tomcat, Jetty, …),
    • Developer Tools (IntelliJ, Eclipse, Netbeans, …)
    • Build automation tools (Maven, Ant, Jenkins, Teamcity, Bamboo, …)
    • Profiling and test tools (JVisualVM, SoapUI, JMeter, …)
  • Methodologies (software engineering approaches and practices):
    • Project level: Agile, Waterfall, RUP, …
    • Engineering level: Dependency Injection (DI), Object-Oriented Development (OOP), Continuous Integration (CI), …
  • Relevant non-Java technologies:
    • Web technologies (HTML, CSS, JQuery, JavaScript, SVG, …)
    • Scripting languages (bash, Perl, ksh, Groovy, ruby, etc)
    • Operating systems (Linux, MacOS, Solaris, …)
    • Database servers (Oracle, MS SQL server, Sybase, …)
    • Team tools (Confluence, JIRA, Crucible, …)
    • Other programming languages (C, C++, Cobol, Fortran, Scala, …)
Categories: java, opinion Tags: , ,

JavaOne 2014 keynote ends awkwardly

October 1, 2014 Leave a comment

Today we watched the JavaOne Technical Keynote at my workplace and the content was fine but a little stale, mostly rehashing last year’s messages, some might even say JavaOne 2014 was “off to a timid start“.

The technical keynote was the final part of a day of keynotes on Sep 28th. Mark Reinhold (Java Platform Architect) looked back at the history of Java, talked about Java 8 and briefly about Project Jigsaw (modules for Java). Then Brian Goetz (Java Language Architect) was finally starting to talk about exciting new initiatives for Java 10 and beyond.

At that point the keynote ended almost rudely, as Reinhold first told Goetz to speed things up, just to then cut him off a few minutes later, taking the slide clickers from him, quickly skipping through remaining slides in awkward silence and ending it with a curt “Have a good week” to the audience.

How unprofessional! Reinhold could have at least smoothed it over by saying that Goetz was trying to explain cool stuff like Value types and refer to a JavaOne session that will go into the details.

Or allow for 10 extra minutes, but maybe Oracle management was too inflexible for that. What a shame and how ironic that the longer term future of Java technology was not important enough. What was the motto of the conference again? “Create the future”? But don’t talk about it for too long, I guess. not found

February 28, 2014 2 comments

Is this the current state of Open Source at Google?

Go to and click on the “Open Source” link under “Developer Programs”:


Categories: coding, opinion Tags: , ,