Recent blog posts from Kevin Webber
Deterministic state evolution is not enough once your event broker provides at-least-once delivery. Idempotence, commutativity, and associativity are the three algebraic properties that protect state-transition functions against duplicates, reordering, and batched folds.
Most event sourcing tutorials teach developers to store events instead of current state, and stop there. Let's go deeper. Automata theory explains why event sourcing works, what properties transitions need, and what breaks under replay.
AI-assisted development accelerates dependency coupling. Onion Architecture, enforced by a strong build system, makes the compiler a structural bodyguard that catches architectural violations at compile time.
The event sourcing community has strong opinions on event naming. In a domain-driven approach, event names come from the ubiquitous language of the business. When events carry their full context, the name does not need to encode what the payload already contains.
A ghost state change is a mutation the system cannot explain. Stronger boundaries, append-only journals, and causal linking eliminate them. Replay proves they are gone.
Fauxpen (faux or false open) represents a trend where commercial software exploits volunteer open source contributions, only to later pivot with restrictive license changes. This post examines the rise of fake open source software, its implications for developers and organizations, and actionable steps to safeguard your contributions and ensure the sustainability of free and open source software…
Producing an ethical benchmark is hard, which explains why high-quality benchmarks are so rare in the industry. The growing trend of biased marketing disguised as analysis, known as benchmarketing, raises critical concerns. This post explores the benchmarketing phenomenon and offers actionable steps toward fostering a more transparent and ethical approach to technical marketing.
The binary search tree algorithm (BST) is one of the most fundamental algorithms in computer science, enhancing tree structures with characteristics that combine the optimal insert with the efficiency of search in an ordered array. Learn this important algorithm by visualizing BSTs with GraphStream, a graph library for Java.
Classical software is primarily based around the notion of decision trees. Any programmer who has coded an if-else-then statement can understand the basics of data science.
When success is ultimately achieved, give the credit to others. There will be time for you to internalize your own impact on the success of a project.
Play embraces a fully reactive programming model through the use of futures for asynchronous programming, work stealing for maximizing available threads, and Akka for distribution of work. Not only does Play have some extreme advantages over servlet-based web frameworks, it also has full support for two of the most popular languages on the JVM, Java and Scala.
It’s been an incredible two-and-a-half years.
Process improvement is the most impactful way to rise above your individual work and impact the overall capacity of the company you work for. All organizations live and die by the quality of their processes.
Akka Streams is a toolkit for per-event processing of streams. It’s an implementation of the Reactive Streams specification, which promises interoperability between a variety of compliant streaming libraries. If you want to get hands-on with streaming, you've come to the right place.
Rather than acting on data at rest, modern software increasingly operates on data in near real-time. Big data is less important than fast data, and fast data is crucial to fast knowledge.
Reactive systems are at the heart of a new breed of enterprise system that fully embraces modern infrastructure.
To understand Reactive — both the programming paradigm and the motivation behind it — it helps to understand the challenges that are faced by developers and companies today compared to the challenges faced only a decade ago.
Advice from a developer who helped rebuild Walmart.ca with Scala and Play.
Agile is challenging to use on certain projects, like those bound by fixed-price, fixed-date contracts. Agencies, governments, and other organizations who are bound by contracts struggle to implement Agile effectively. We'll explore ways that we can borrow the best processes from Agile when we're bound by the limitations of fixed-price contracts and statements of work.
Joy isn't the typical emotion that comes to mind when one pictures enterprise software and enterprise software developers, but technical culture is changing rapidly and more people are recognizing the business value of joy. It's an exciting time to be a software developer.
It was big news in 2010 when Twitter migrated their search from Ruby on Rails to Java-based Netty. Not only was it big in the news department, but it was also big in the results department: Twitter reported their search performance increased by 3x. In this post we'll explore Netty by using it to build a game of multiplayer tic-tac-toe.
A page I'm working on accepts multiple image uploads. Once the images are successfully processed asynchronously on the server, an image panel on the same page is automatically refreshed. The AJAX callback works fine and updates the panel view with the newly uploaded photos, but the net result is that Fancybox stops working completely.
Hibernate uses it’s own built-in connection pool out of the box. There are some pretty heavy duty sites running with the default connection pool enabled in production despite the obvious warning against doing this.
We explore a Forrester report which asserts that Java is a dead end for enterprises and business software should be built with a 4GL such as webMethods. Let's explore why Java won't disappear from the enterprise any time soon.
Java is a utilitarian, status-quo ecosystem for getting things done, albeit not very quickly. This is a good thing. Instead of worrying about sharp edges, developers get to work with a very stable, very slow moving target. What's the future hold for enterprise Java developers?
A desire path represents the evolutionary nature of how people interact with their environment. An engineer designs a concrete path, but people find it more convenient to create their own. Software isn't any different. Users bump up against the limitation of an application but find their own workaround through sheer necessity.
One of the most requested features on any site that accepts file submissions is the ability to handle multiple uploads elegantly. The current HTML standard only permits one file upload at a time, which makes transferring a large number of files quite tedious. This tutorial will show how to painlessly integrate Uploadify and Java using Apache Wicket.
Good developers always try to deliver amazing software in spite of obstacles. The perfect methodology for our team may not integrate well with the rest of the organization. The perfect programming language may be unknown to most developers on the team. The perfect architecture may require three months to develop but the deadline is three weeks away. Good developers embrace a harmonious balance…
It looks like enterprise developers are in for a real treat: the missing secret sauce that allows enterprise application developers to harness the goodness of OSGi.
In my experience I've noticed that flexible and adaptable organizations produce flexible and adaptable applications. Rigid and inflexible organizations tend to produce rigid and inflexible applications. Co-incidence?
The spirit of SOA is fantastic; adaptable, flexible, maintainable, loosely-coupled applications supported by open governance, strong relationships between business and technology folks, and co-operation across all silos and levels of an organization. What's not to love? We'll explore the pitfalls of SOA and explore the future of SOA in the enterprise.