Events should always be self-contained

2020-03-31

The term Event-Driven can mean different things for different people. Fowler (2017) (opens new window) identifies three categories of events. However, the topology misses to discuss the contents for each kind of event. I present a classification of events based on their payload and argue that events should always contain the whole state of the modified entity in the context of Distributed Systems.

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The Maintainability Benefits of Property-Based Testing

2020-03-24

Traditional tests are example-based. Many different examples are needed to cover all edge cases of a system under test, which often leads to bloated test suites that eventually become a maintenance burden. This article presents the idea of property-based testing using an HTTP API as example. It shows that property-based tests result in concise and more maintainable test code.

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The importance of client-side libraries for APIs

2020-03-16

Accessing different programs over the network is the norm in a distributed system. Many programs provide programming interfaces that can be used by others. More often than not, software solutions with an HTTP API simply publish its specification on a website and are done with it. This causes a bunch of different problems for users of the API. In this article I argue about the importance of providing client libraries for APIs.

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Choose your software platform carefully

2020-03-09

The choice of a software development platform is the most profound technology choice in a software project. A platform enables rapid development in some direction, but constrains the development process in other directions. It is the software architect's responsibility to make a choice based on the affordances and restrictions of available platforms.

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Building Transactional Systems Using Apache Kafka

2019-08-20

This guest post on the Confluent blog presents one way to create an event-based architecture based on Apache Kafka. The resulting software system retains most transactional properties as provided by an RDBMS.

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Staves – A Container Image Builder based on Gentoo Linux

2019-02-26

I came across a couple of articles about packaging container images, specifically for Docker. The fact that many people are working on their own solutions indicates that the Dockerfile syntax is lacking.^[1] Buildah (opens new window), for example, promises more low-level control over the creation of image layers. Projects like deck-build (opens new window) or Kubler (opens new window) try to give the user more high-level abstractions by providing composition and more expressive commands that can be run during build. In this article, I present my reasoning why the existing tools were not suitable and show what the Staves (opens new window) image builder is capable of. You can either hear me out or skip the rationale and dive directly into Staves. Knowledge of Gentoo Linux is helpful, but not strictly necessary.

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Fetching packages from authenticated HTTP URIs with Gentoo Portage

2019-02-08

Gentoo Linux's package manager Portage is designed to build packages from source code. Packages are installed from ebuilds which represent the installation instructions for a given software. Ebuilds specify the location of one or more source archives which are automatically fetched by the package manager. Several URIs are supported: http and https, ftp and sftp, rsync, and ssh.^[1] This works perfectly well for open-source software, where the source tarball is publicly available. However, if the sources are not public, things get more complicated. In this post, I present different ways to fetch tarballs from URIs that require authentication.

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Breaking up the Monolith – Assessing the status quo

2018-11-13

Breaking up the Monolith is a series of articles about transforming a concrete monolithic application into microservices. This post shows my personal decision making approach on the matter. The architecture of the Ameto image processing service (opens new window) will serve as an example.

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A unified data model for token-based authentication and credential authentication

2018-07-28

Read about how the authentication system in Ameto (opens new window) has evolved over time. I evaluate different approaches for modeling user data for token-based and user-password authentication and present a secure approach for treating them uniformly in the data model.

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Multi-Tenancy Data Models in Kafka

2018-07-02

Data modeling for relational databases is a well researched field. NoSQL databases, however, are more specialized and require different approaches for deriving an appropriate data model. My current project Ameto (opens new window) is making use of the distributed streaming platform Apache Kafka. Ameto is a multi-tenant application and requires an appropriate data model. While there is some advice available on the internet about how to organize your data in Kafka,^[1] little can be found about how multi-tenancy can be approached. In this article, I would like to share my thoughts and findings about structuring your data in Kafka for a system with multiple users.

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