with a nice camera remote control

[Click here for the German text version.]

My new project is finished. Normally I build websites… This time, I wanted to create something real! :-)

So I drive my Raspberry Pi through my flat… with two continuous servo motors, wheels, wireless power and a smartphone camera control.

What did I need?

mit einer praktischen Kamera-Fernbedienung

[Click here for the English Text Version]

Mein neustes Projekt ist fertig. Sonst baue ich Webseiten… Dieses Mal hatte ich Lust auf was Echtes! :-)

Also lasse ich meinen Raspberry Pi durch die Wohnung fahren… mit zwei Servomotoren, Rädern, kabellosem Strom und einer Handy-Kamera-Steuerung.

Was habe ich dafür gebraucht?

Ever wanted to develop a web application with an easy to use, yet powerful persistent item storage? Then how do you like this one?

I finished the first version of the POCZone.net Client API. It is written with Google Web Toolkit (GWT). GWT allows you to develop web applications in Java. These applications are compiled to JavaScript. A GWT application can easily include my Client API.


  1. Create new items, list all items or get items by their ID.
  2. Get and put item properties synchronously and delete items. Each item is a JSON object.
  3. Local changes will be synced with…

Management of shared spaces and invocation of apps

I proudly present the first version of the Portal Application for my website POCZone.net!

POC is for Proof of Concept. The website hosts a bunch of experimental note taking applications. I’m currently rewriting it. The main design goal is to have a platform that handles all the common app requirements, so the apps can focus on what’s important. I had a week of home vacation in December 2017 and I made good progress! So here we go!

For the bigger picture, read this always up-to-date index article:

Summary (Platform Concept)

Let me summarize the platform concept. …

HTTP Interface for Authentication + Space Management + JSON Data Storage

I finished the Backend Service for the rewrite of my website POCZone.net! POC is of Proof of Concept. For an always up-to-date index article with the bigger picture of the rewrite, visit this story:


The Online Instance of the Backend Service is up and running. You can visit it here:

The source code is available at GitHub:


The Backend Service provides all the functionality! It is written in Java with Servlet API + JDBC MySQL + JSON API.

The code is split into a “framework” and a “backend” part. …

Shared App Spaces with Live JSON Data

I’m currently rewriting my website POCZone.net (with POC = Proof of Concept). The website offers experimental note taking applications. This article covers the requirement analysis and the platform concept.

For an overview of the progress and all articles, visit the following story.

Requirements? A lot in common…

Most of my applications are note taking apps — ToDo lists, Kanban boards, diaries, wikis, etc. I discovered, they have a lot in common:

  1. User context: They require authentication and data must be stored confidentially.
  2. Spaces: I want multiple isolated spaces for each app (e.g. Work, Private, Project A, Project B, …).
  3. Collaboration: I want to share spaces…

I love programming! And I love to experiment and create new web applications. This is why my website is called POCZone.net (with POC = Proof of Concept).

I’m currently rewriting the entire website and want to take you with me on the journey!

This article serves is an index and links articles with published work! It will be updated to reflect the status of the development. I also outline the next steps.

Articles about finished work

What’s next?

Next, I will…

  1. Simplify my existing Apps with the use of the new Client API.
  2. Create new Apps.
  3. Include third party apps, when someone wants to create one…

We hold these truths to be self-evident…

  • that no image must ever be distorted in its aspect ratio!
  • that the only valid image transformations are clipping, rotation and aspect ratio preserving scale operations (+ flipping in edge cases, although some hard-liners will probably not agree on that).

We have been silent for too long!

Speak up against this madness!

(inspired by Carsten Sander)

Have you seen this great TED Talk about how to improve? I found it fantastic!

In his talk, Eduardo Briceño distinguishes between the “Learning Zone” and the “Performance Zone”.

The performance zone is the main part of our work. It’s where we apply our skills, execute, try to minimize mistakes and achieve our best results.

The learning zone on the other hand is all about improvement. We focus on what we don’t know, experiment, learn and make mistakes in a low-risk setting, so we can learn from them and get better.

Don’t just do, do, do.

The problem why many people don’t improve, as…

Hendrik Ewerlin

Web software developer + philosophy lover. See https://hendrik.ewerlin.com/ for projects.

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