A Java geek

Dynamic watermarking on the JVM

Displaying images on your website makes for an interesting problem: on one side, you want to make them publicly available; on the other, you want to protect them against undue use. The age-long method to achieve it is watermarking: A digital watermark is a kind of marker covertly embedded in a noise-tolerant signal such as audio, video or image data. It is typically used to identify ownership of the copyright of such signal.

Technical

Renovate for everything

In my earlier post about moving from Kotlin Scripting to Python, I mentioned several reasons: Separating the content from the scriptKotlin Scripting is an unloved child of JetBrainsRenovate cannot update Kotlin Scripting files I was wrong on the third point. Here’s my mea culpa. First things first, Renovate does indeed manages Kotlin Scripting files - since 2022. Even better, Renovate can manage any type of file.

Technical

A refresher on GitHub Pages

I moved my blog from WordPress to GitLab Pages in… 2016. I’m happy with the solution. However, I used GitHub Pages when I was teaching for both the courses and the exercises, e.g., Java EE. At the time, there was no GitHub Actions: I used Travis CI to build and deploy. Recently, I had to use GitHub Pages to publish my Apache APISIX workshop. Travis is no longer free. GitHub Actions are a thing. I used the now nominal path and faced a few hurdles; here are my findings.

DevOps

Random and fixed routes with Apache APISIX

My ideas for blog posts inevitably start to dry up after over two years at Apache APISIX. Hence, I did some triage on the APISIX repo. I stumbled upon this one question: We have a requirement to use a plugin, where we need to route the traffic on percentage basis. I’ll give an example for better understanding. We have an URL https://xyz.com/ca/fr/index.html where ca is country (canada) and fr is french language. Now the traffic needs to routed 10% to https://xyz.com/ca/en/index.

DevOps

Even more Opentelemetry!

I continue to work on my Opentelemetry demo. Its main idea is to showcase traces across various technology stacks, including asynchronous communication via an MQTT queue. This week, I added a couple of components and changed the architecture. Here are some noteworthy learnings; note that some of them might not be entirely connected to OpenTelemetry. Here’s an updated diagram. New components appear in violet, and updated components appear in green.

Development

Parsing structured environment variables in Rust

I’m in the process of adding more components to my OpenTelemetry demo (again!). The new design deploys several warehouse services behind the inventory service so the latter can query the former for data via their respective HTTP interface. I implemented each warehouse on top of a different technology stack. This way, I can show OpenTelemetry traces across several stacks.

Development

Workflow, from stateless to stateful

A (long) time ago, my first job consisted of implementing workflows using the Staffware engine. In short, a workflow comprises tasks; an automated task delegates to code, while a manual task requires somebody to do something and mark it as done. Then, it proceeds to the next task - or tasks. Here’s a sample workflow: The above diagram uses Business Process Model and Notation. You can now design your workflow using BPMN and run it with compatible workflow engines. Time has passed.

Development

My opinion on the Tauri framework

I’ve always liked GUI, both desktop-based and browser-based before you needed five years of training on the latter. That’s the reason I loved, and still love Vaadin: you can develop web UIs without writing a single line of HTML, JavaScript, and CSS. I’m still interested in the subject; a couple of years ago, I analyzed the state of JVM desktop frameworks. I also like the Rust programming language a lot. Tauri is a Rust-based framework for building desktop applications.

Technical

The Vary HTTP header

I try to constantly deepen my knowledge of HTTP and REST. Recently, I stumbled upon the list of all registered HTTP Headers. This post is dedicated to the Vary HTTP Header. The problem Two years ago, I wrote about web resource caching server-side. The idea is to set up a component between the client and the upstream to cache previously computed results to avoid overloading the latter. Depending on your infrastructure and requirements, this component can be a reverse proxy or an API Gateway.

Nicolas Fränkel's blog