Johannes Neubauer – Page 2

Spring Boot Passthrough JWT with RestTemplate

20. July 201920. July 2019 jonny Leave a comment

In a microservice environment it is often the case, that calls from a client to a service result in further calls to other services. One possible scenario is a call to a GraphQL service which gathers information from different backend (REST) services and present it as a cohesive data graph.

In this scenario the user is authenticated to the backend services via OAuth2 (e.g., Keycloak or a Spring Boot OAuth2 server) and the GraphQL service should passthrough the authentication header (a JWT bearer) of incoming requests to the backend services. This way the authentication has to be validated only once in the backend services and as “near” as possible to the (REST) resources.

This is not meant as a replacement for service-to-service authentication, but as an addition if you do not use the full OpenID connect standard with a separate identity token to pass on, but still want to serve verifiable user data to your backend service. In contrast, you may use this to pass through any header (including a identity token). This is just a scenario that I faced.

Repair a Damaged Package System after Ubuntu Dist-Upgrade

5. January 20195. January 2019 jonny Leave a comment

Happy new year.

My blog runs on a VM at Hetzner with an Ubuntu LTS system. That means 5 years of support… I was running trusty from 2014, so there should be support until 2019. But not every open source software has given you this promise, just the Ubuntanians. So, support for Owncloud run out last year and I thought that the days between years are a good time to switch to a new version.

Hence, I did two dist-upgrades after another from trusty to xenial and from xenial to the current LTS version bionic (every 2 years a new LTS version is coming out). The first upgrade was “successful” with a lot of need for adaption in the configurations afterwards. Then after everything worked again, I did another upgrade, which failed because of this issue.

You do not want your system showing you such a message during `do-release-update`.

That is, I had to fix a distro upgrade that failed in between… challenge accepted 🤓.

Change c-time on Unix-Based Systems Based on Filenames

5. January 20195. January 2019 jonny Leave a comment

For quite some time I have a paper-free office (at home). I still physically file the papers I get, but in addition I scan all the paper documents, tag them and put them in a folder. I use a very easy system. For the very recent documents (and the ones work in progress) I have a draft folder. Furthermore, there is exactly one document folder per year and I store everything in there (incoming and outgoing documents, scanned ones and ones that I get mailed, even some printed to PDF emails for document-like emails). Each file has a common naming scheme. There is one part that is relevant for this post: at the beginning of each file I put the date of the document in the format YYYYMMDD. This way, the documents are ordered chronologically in a year, if I sort them by name. There is a lot more to my filing system and if someone is interested, please leave a comment, but for this post, this should be enough about my way of filing documents (digitally).

The issue I would like to address here is, that the date when I scanned a file and the “real” date of the document diverges. Sometimes it even happens, that the creation time of two scanned files are in “the real world” in one order, but the scan-/creation time is the other way around. I do not like this situation. Therefore, each year when I “finish the year”, I run a script (on macOS), which adapts the ctimeto the date-part in the name of the file (a one-liner, which I put on 5 lines, for better readability):

find . -name "2017*" | while read file; \
  do thedate=$(echo "$file" | \
  sed -E 's/^[^0-9]*([0-9]+).*$/\1/'); \
  touch -t ${thedate}0000 $file; \
  done

If you have another unix-based System with sed you can use -r instead of -E. I am unsure why this option behaves differently on macOS although I installed (and use) GNU sed installed via home brew.

Exciting 🤓.

Creating an Alpha Channel Video with Final Cut Pro X

2. July 20182. July 2018 jonny Leave a comment

Lately, I faced the task to make a long-term-support (LTS) backup of a FCP X “green screen” video project. I had two constraints:

The result should take a “small” amount of disk space, only.
It should be possible to alter background, text effects, image effects and so on without loosing quality.

The original data took about $500$ GB, because of junk takes. But, I wanted to store $30$ – $50$ GB, only. Unfortunately, we chose to take very long shots, so that it was not easy to remove the junk from the FCP X project file (there are paid solutions for this, but the ones I found do not work with combined clips). Just rendering the video in good quality would solve constraint one (C1), but it is hard to make changes to such a file (C2).

Therefore I chose another road: Render the green screen scene with an alpha channel as one long video, in order to sort the wheat (good video) from the chaff (bad video). Using the original green screen instead of an alpha channel was not an option, since I animated the green screen video channel (e.g. moving it from the left to the right) which added black “letter-boxes”. An easy solution would have been to use the keyer to remove the green screen and add a new one via a green background (i.e., an artificial green screen). This can be rendered to a video and a second keyer can be used after a reimport. But this seemed kind of lame (in terms of unprofessional) to me. I wanted a cool alpha channel video as I have seen it in the making of of several films, with an additional video (channel), which is just black and white containing the alpha information.

So, I googled and there was surprisingly sparse information on this topic. There are some formats that should be able to contain an alpha channel like Apple Animation, Apple ProRes 4444, but they all have in common, that they take an unbelievable high amount of disk space, which violates C1 (and they didn’t work for me…). I didn’t find any HowTo or tutorial in THE INTERNET that could help me.

Challenge accepted. 🤓

Inherit TimeMachine Backups

4. March 20174. March 2017 jonny Leave a comment

Lately I had to restore my macbook from time machine. Luckily, the reason was that I got a new MacBook 🤓. So I created a last time machine backup, said goodbye to my old macbook, and moved on to my new machine, starting with restoring from my all new time machine backup. I did this several times now and it went well every time. And… no problem this time either and this is what I tell all my jealous Linux and Windows friends. But what I didn’t tell them is that the next step is less fun: inheriting the backups of the old machine.

DIME Landing Page is Online

9. October 20169. October 2016 jonny Leave a comment

In March I wrote about a new project called DIME (Dynamic web application Integrated Modeling Environment), which enables to create full-fledged web applications via a family of GDSLs (Graphical Domain-Specific Languages), with an additional textual representation. It is the beginning of a development style, where technical experts and application experts (e.g., business experts) can work together on one artifact. The underlying idea of the approach is, that the different types of modeling languages (for data, control, and user interface) are interdependently connected and describe the application completely, so that they can be full code generated to a ready-to-use web application. Everything that cannot be captured adequately on the model level, can be integrated in a service-oriented fashion via so called native components.

At the end of that post I announced a DIME landing page, created with this very tool. Now a first version is online, which is responsive and shows already a few dynamic features, like internationalization (you can choose between english and german in the menu) and a comment form, where you can leave your first impressions. But please be kind, the Add Comment-process informs us about new comments and we can delete rude commments in the private area (all generated). The site is work in progress, we will update it with new features, more information, news on public events, and projects where DIME has been used. Further on, we will add a download section as soon as time has come for going public with DIME.

We already have some nice demo applications like a TODO-App as well as a “Reddit”-Clone, which will ship with the DIME installer. Just last week we held a DIME workshop on STRESS’16 co-located to ISoLA 2016 conference.

So please, take a look at the DIME landing page, leave a comment, and stay tuned for more to come.

Exciting, 😉.

Interview with Dr. Jan Köhnlein on Xtext, Xtend, Xcore, FXDiagram, and TypeFox

30. July 201630. July 2016 jonny Leave a comment

Dr. Jan Köhnlein is one of the founders of TypeFox, the moving force behind Xtext, Xtend, and FXDiagram. This is a very extensive follow-up interview to this one. Thanks again to Jan!

Dear Jan, thank you very much for your time. I really like the ecosystem around Xtext, Xtend, Xcore, Xbase, and EMF. I think it is one of the most-disrupting decisions (in a positive way) that, starting from 2.9.0, you address more than just the Eclipse platform! But with this new approach and your all new company TypeFox (as well as the spin-off from itemis), some questions arise…

Using AVFoundation to Play Audio in an SKAction in SpriteKit

16. July 201616. July 2016 jonny Leave a comment

SpriteKit offers two ways to play audio:

SKAction.playSoundFileNamed:waitForCompletion: for playing a sound once
SKAudioNode (since iOS 9): for playing background music in a loop, or do other advanced audio stuff like positional audio (3D spatial audio effects).

The first option is quite unflexible. It just plays the sound once. You cannot change the volume or put any effects on them. SKAudioNode on the other hand offers a lot of cool features via SKActions like changing the playback rate and volume and adding live effects like reverb.

This seems to be a no-brainer. I tried it in my game Fusionate and there was a real bad whistling sound, although I didn’t use any effect or positional audio (just volume changes). So, back to the first option and create a lot of audio files by hand, in order to get the desired effect even for simple things like changing the volume?

No way…

Enhancing Mustache via an if-Statement with EL

8. July 20168. July 2016 jonny Leave a comment

Mustache is a well-adopted template language which itself says that it is logic-less. So, there are pseudo-logic statements, which allow to iterate over a list or do a null-check, and it is possible to add arbitrary (unparameterized) template function. But they make a hold when it comes to an if-statement with a boolean check.

There is a lot of discussion going on in the net^tm on why a null-check and template functions are ok, but an if-statement and parameters are not… but hey we have template functions, so why not add our own implementation of such things?

Convert Markdown to PDF

22. June 201622. June 2016 jonny Leave a comment

Lately, I wrote a small text in markdown and felt the need to share it with someone (non-technical). I searched for solutions to convert markdown to PDF and was very surprised, that there were only so-so solutions. After some googling and coding I found an easy to use solution which comprises a markdown tool for converting markdown to html and phantomJS (a headless WebKit scriptable) for converting html to pdf. The cool things: hyperlinks and custom css work.