workflow camunda state

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. Sta

Rust Tauri GUI

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. Here&


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. H


Five ways to pass parameters to Apache APISIX

I recently read 6 Ways To Pass Parameters to Spring REST API. Though the title is a bit misleading, as it’s unrelated to REST, it does an excellent job listing all ways to send parameters to a Spring application. I want to do the same for Apache APISIX; it’s beneficial when you write a custom plugin. General setup The general setup uses Docker Compose and static configuration. I’ll have one plugin per way to pass parameters. docker-compose.yml services: httpbin: ima

Rust error management

The try block in Rust

I wrote previously about libs for error management in Rust. This week, I want to write about the try block, an experimental feature. The limit of the ? operator Please check the above article for a complete refresher on error management in general and the ? operator in particular. In short, ? allows to hook into a function call that returns a Result: If the Result contains a value, it continues normallyIf it contains an error, it short-circuits and returns the Result to the calling function.

Languages Design Object Orientation Functional Programming

Dissolving Design Patterns In Design Elements

The book Design Patterns: Elements of Reusable Object-Oriented Software was one of the texts that changed how we think about software design. This book came out in 1994 through the efforts of Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides, later remembered as Gang Of Four (GoF) GoF Design Patterns: The Origin, the Impact The book’s importance lies in its effort to review the software production done up at that moment, giving more structure to the concept of Software Design


Implementing the Idempotency-Key specification on Apache APISIX

Last week, I wrote an analysis of the IETF Idempotency-Key specification. The specification aims to avoid duplicated requests. In short, the idea is for the client to send a unique key along with the request: If the server doesn’t know the key, it proceeds as usual and then stores the responseIf the server knows the key, it short-circuits any further processing and immediately returns the stored response This post shows how to implement it with Apache APISIX. Overview Before starting

HTTP APIs REST idempotency IETF

Fixing duplicate API requests

The first rule of distributed systems is 'Don’t distribute your system'. Designing distributed systems right is infamously hard for multiple reasons. The idempotency concept For example, a call to a function can succeed or fail in non-distributed systems. Once you move the called function to a remote component, a third option appears: you call the remote function but get no response from the component. At this point, it’s impossible to know whether the call reached the component o

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Apache APISIX North America Tour

Once in a while, I write non-technical blog posts when I’ve something worth sharing. Today, I’d like to write about my North America 'Tour' across several conferences and user groups. The first leg of my journey started in Oakland, California, with Developer Week. Developer Week is an established conference with different editions in several locations and online during the year. Though I’m on their advisory board, this is only the second time I’ve spoken at one of their

programming coding rust kotlin

The pitfall of implicit returns

Implicit returns are a feature in some languages. They have recently bitten me, so here’s my opinion. Statements, expressions, and returns Before diving into implicit returns, we must explain two programming concepts influencing them. A lot of literature is available on the subject, so I’ll paraphrase one of the existing definitions: An expression usually refers to a piece of code that can be evaluated to a value. In most programming languages, there are typically three differ