When we began the development of our new Online Shop otto.de, we chose a distributed, vertical-style architecture at an early stage of the process. Our experience with our previous system showed us that a monolithic architecture does not satisfy the constantly emerging requirements. Growing volumes of data, increasing loads and the need to scale the organization, all of these forced us to rethink our approach.
Therefore, this article will describe the solution that we chose, and explain the reasons behind our choice.
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).
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.
LHOTSE is the internal code name for our project to re-develop www.otto.de: in-house, based on open source software and using agile methodologies such as Scrum and XP. LHOTSE went live on 24th October 2013 – three months before schedule. Although it took us roughly two years to develop, with a team of more than 100 experts, getting LHOTSE live was practically a „non-event“. So, why did everything work out so well?