On March 6th, we hosted the Varnish Developer Day VDD at our Loft 6. We are proud to give the community a place to meet and to support the open source project Varnish.

Why do we do this?
Varnish is one of the main software products we have integrated into otto.de to make our shop fast and to achieve our business goals. Keeping in mind that we have a ’shared nothing‘ software architecture, we need at least one central system where everything comes together. How should each of our independent applications receive HTTP requests? A reverse proxy fulfills this role naturally.

Abstract: „Der Trend zu Microservices in komplexen Systemumgebungen ist die architektonische Antwort auf agile Softwareentwicklung und Continuous Delivery. Kleine Systeme, die unabhängig voneinander entwickelt und separat betrieben werden können – eine Architektur als Enabler für das Business. Den Vorteilen gegenüber stehen aber die klassischen Herausforderungen der Integration. Wie sehen Integrationstests aus, wie kann der übergreifende Betrieb sichergestellt werden und wie werden fachliche Abhängigkeiten behandelt? In diesem Vortrag werde ich anhand der neuen E-Commerce Plattform von OTTO aufzeigen, wie wir den Monolithen Otto.de in vertikale Systeme aufgeteilt und dadurch ein agiles Arbeitsumfeld ermöglicht haben. Besonders für die organisatorischen Konsequenzen werde ich Lösungsansätze mit ihren Vor- und Nachteilen vorstellen. Klassische Querschnittsaspekte wie Tracking, Performance und Security haben wir in die Architektur integriert und diese damit im Laufe der Zeit kontinuierlich weiterentwickelt.“

Die MicroXchg Konferenz am 12./13. Feb. 2015 in Berlin war die erste exklusive Konferenz zum Thema Microservices. In zwei parallelen Tracks gab es verschiedene Vorträge zum Thema Microservices – national und international, aus Anwender- und Beraterperspektive, von Microservice-Pionieren und Kritikern. Dieser Artikel fasst die wesentlichen Aussagen meines Vortrags zusammen und reflektiert die Reise der Otto.de Architektur von einem klassischen Monolithen zu einer verteilten Architektur mit Microservices.

Gibt es etwas zwischen Microservices und monolithischen Architekturen? Die Antwort lautet natürlich: JA. Aber warum?

Recently we released tesla-microservice to github. It is a software written in clojure and it is the basis of some of the microservices we are working on as part of the technical platform of otto.de. We named our software after Nikola Tesla an ingenious engineer and inventor of the late 19th and early 20th century.

tesla-microservice is based on the component library, an elegant and quite minimal framework to build stateful applications in clojure.

Currently tesla-microservice allows you to build a basic web application with some basic features:

  • Load config from classpath and/or filesystem.
  • Aggregate a status based on the status of the different components and their subcomponents.
  • Deliver status details as json.
  • Serve a simple healthcheck based on that status.
  • Report to graphite using the metrics library.
  • Manage routes using compojure.
  • Serve content with an embedded jetty.


Performance has become critical to the success of websites, and of e-commerce sites in particular. With customers expecting web pages to load increasingly faster, they will often lose patience, especially in a purchase process, if they have to wait for too long. The key question is figuring out how long each of the various pages can be allowed to take – at maximum – to load and present relevant content in the browser.

This leads to the next question: what is the relevant page content? What are the must-have elements, and which functions have to be accessible in order for the page to catch and retain the user’s attention? At OTTO we have been engaging with these questions for a number of years, and have made some interesting discoveries during this time.

OpenSpeedMonitor-on whiteIn this process, iteratec has been assisting us in designing the concept and taking the system into practice. Our collaboration over the past two years has produced a tool for measuring the performance of websites: the OpenSpeedMonitor, which we would like to introduce here.

Logo Velocity

Uwe Beßle and Nils Kuhn from iteratec will be presenting the tool on November 18-th at the Velocity Europe Conference event. In this first part of our interview, they give us an overview of the OpenSpeedMonitor tool and a taste of their Lightning Talk in Barcelona.

The architecture of otto.de is based on the concept of vertical decomposition: the whole system is vertically split into several loosely coupled applications.

Every „vertical“ is responsible for a single business domain such as „Order“, „Search & Navigation“, „Product“, etc. It has its own presentation layer, persistence layer and a separate database. From the development perspective, every vertical is implemented by exactly one team and no code is shared between the different systems.

We have already described the details of this architecture in an article in  OBJEKTspektrum (German), a different blog post (German) and at conferences like QCon (English).

Vertical Decomposition
Vertical Decomposition

For some time, a different approach to decompose large systems is becoming more and more popular: microservices. What are the similarities and differences of both kinds of architectures and how is it possible to get the best of both? This is what I want to discuss in this text.

This is part two of my roundup of  EuroClojure 2014. If you missed the first part, find it here.

Day two started with the keynote by David Nolen about Invention, Innovation & ClojureScript. After some interesting discussion on the difference between invention and innovation, he talked about the history of clojurescript, a clojure implementation that does not target the jvm but javascript as a runtime environment. It was released 3 years ago and since then undergoes constant innovation. To date, the innovations come from 81 different contributors. Examples for contributed innovations are persistent immutable datastructures and source maps, which are very useful for debugging clojurescript. David introduced the basics on react.js and then of om. Om is a clojurescript library on top of react.js. It adds a key ingredient to react: Immutability. By having an immutable global application state, communication between components becomes feasible without any of those crazy interactions, that make classical user interface development so hard. As an example David  showed Goya, a pixel editor for the browser. Due to clojurescript’s persistent datastructures it features undo/redo of a virtually unlimited number of steps with little to no performance impact at all. David finished with an outlook on clojurescript 1.0. Among the goals is better code sharing between clojure and clojurescript.