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Mail: stefan.bente@th-koeln.de
Tel.: +49 2261 8196 6367
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Adresse:
Steinmüllerallee 4
51643 Gummersbach
Gebäude LC4
Raum 1708
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GP »Event-Driven Architecture in an eCommerce Application« (GP Event-Driven Architecture in ECommerce (WS23)), WS23

In this project, an eCommerce application is to be implemented using a microservice architecture. In order to achieve the highest possible resilience and decoupling, the services should communicate asynchronously with each other based on events. The goal is to explore the asynchronous pattern, overcome “mental model”, and look for good programming practices along the way.

Keywords
event-driven architecture, domain-driven design, microservice, eCommerce, software architecture
Study Program and Module Description
Master Digital Sciences (specialization Software Architecture) (see also module description in the study program web site)
Begin/End and Scheduling
Beginning of October - End of Feb 2024. Organized as an agile project with sprints every 2 weeks. Workload depends on the type of project, will be clarified at kickoff.
Location
The module takes place in a hybrid format. Please refer to the respective time slot or workshop day (see below on this page), to check if it is online or in presence. If there are no details given on this page, please check the other communication channels (e.g. Discord).
Room 1: 1708 (Building LC4 (library building). Room 1708 is our lab office space, with enough room for small workshops. However, the room is only accessible with by transponder. Thereore, please be at the door left of the library entrance (where you see the label "Kriminalkommissariat", since the Gummersbach police criminal investigation unit is our office neighbour :-). I will fetch you there. Call me (+49 176 8072 2689) or a fellow student by mobile phone in case you should run late), see also detailed directions
Room 2: Innovation Hub (Building LC7, the building to the right of the passage to Gummersbach station. The Innovation Hub is not not open to the public. However, the main entrance door is open during office hours. Come up to the second floor and ring the bell there. Please call me (+49 176 8072 2689) or a fellow student by cell phone if no one answers), see also detailed directions
Video conference link: https://th-koeln.zoom.us/j/4425088059?pwd=bxHOJB7D3pBHdTpruFHSdC1Y66e9Rr.1
Discord Server for fast Communication
Discord has been proven as a very effective platform for information sharing, discussions, and consultations. Therefore, please join the ArchiLab Discord Server at https://discord.gg/YYNYb5whU8. Navigate to channel #rollenzuweisung and click on gp. Then you see all channel(s) relevant for this module.

Content

Problem Description

When making decisions within a software architecture, there is no right or wrong, there are only trade-offs. This also applies to the communication between microservices. In a previous project in the Coding Excellence (CEX) module, an attempt was made to find out what are the trade-offs between synchronous and asynchronous communication, based on events, between services using the microservice architecture of an eCommerce store.

As it turns out, it’s noticeably difficult to switch from a synchronous to an event-based architectural style. It seems that our “software education” is preparing us to think in a synchronous request / reply pattern. When switching to an asynchronous implementation, this mental model needs to be overcome, or else we’ll implement a synchronous communication pattern using asynchronous technology - and therefore will not work truly event-based. The story so far can be examined in a paper written in the module CEX.

Project Definition

An eCommerce application is to be implemented using a microservice architecture. In order to achieve the highest possible resilience and decoupling, the services should communicate asynchronously with each other based on events. Beside the event-driven service architecture, the project is focusing on

  • asynchronous test concepts (Test driven design, TDD)
  • hosting / dev-ops approach (CI / CD), and
  • security aspects (https/encryption, authentication).
  • The goal is to explore the asynchronous pattern, overcome “mental model”, and look for good programming practices along the way. There should be even more unit tests that in a traditional test pyramid and even less integration tests. This is because in async/events, there is a larger proportion of business logic expressed as pure functions, thus unit-testable.

The “ops” part of the project is explicitly part of the implementation, trying for a true “DevOps” approach where the development team also tackles ops architecture and implementation.

Project Outcomes

The following outcomes should be delivered by the project:

  • MVP with robust, near-production-level code
  • Tests
  • A delivery pipeline able to deploy the MVP to a laboratory environment, from day one
  • Documentation with an assessment / reflection of the architectural patterns used

If there is enough time, the following aspects would be an interesting extension:

  • Minimal observability capacity for microservices participating to the product
  • Minimal identity and access management for microservices participating to the product
  • Operational experimental setup able to demonstrate the resilience of the product under several service disruption scenarios
  • Operational experimental setup able to demonstrate the resilience of the product under heavy payloads

Learning Outcome

  • Understanding what a event based communication truly is
  • Knowledge about microservice architectures
  • Tradeoff for asynchronous communication between microservices with event-based message brokers
  • Testing in a asynchronous environment (e.g. unit tests, integration tests, end2end, …)
  • Knowledge in the Dev-Ops approach
  • Learning from practitioners (Michaël and Wolf from ThoughtWorks)

Requirements for participating

  • Solid coding experience in Java, .NET Core, or any other language suitable to implemented a microservice
  • Interest in architecture patterns and good practices in coding
  • Frontend or backend experience
  • Experience with an event broker (Kafka) helps, but is not a must

External Project Partner

ThoughtWorks, with Wolf Schlegel and Michaël Le Barbier both working for thoughtworks.com

Grading

The grading for this Guided Project will follow the general grading scheme for Guided Projects outlined here.