Event-driven & Workflow-supported Microservice Landscape

Situation & Challenges

Wiener Wohnen Kundenservice (WrWKS) operates a large, complex IT landscape to support the diverse service processes for the city of Vienna. Prior to the project, applications and data flows were highly coupled, leading to high dependencies, limited scalability, and complex maintenance. At the same time, the demand for flexible, high-performance systems, capable of distributing data in real-time, grew.

Core Problem:

• The existing architecture no longer met the requirements for modularity, performance, and asynchronicity

• Processes were difficult to coordinate in real-time or scale efficiently

• High maintenance efforts due to monolithic or tightly coupled components

Solution – Architecture & Implementation

To address these challenges, an event-driven, decentralized microservices architecture was implemented, utilizing modern technologies for decoupling and scaling:

Event-Driven Microservices

• Core processes as individual, loosely coupled services

• Data and states are asynchronously distributed via event streaming

Apache Kafka for Real-Time Communication

• Central event pipeline ensures reliable data transport between services

• High throughput rates and scalability for live workflows

Workflow Engine with Camunda BPMN

• Modeling and controlling complex business processes

• Transparent process execution across different services

React Frontends & Modern JVM Services

• User-friendly web interfaces connected with robust backend services

• Microservices with Kotlin and Spring framework

Cloud-Native Deployment with Kubernetes

• Container orchestration for automatic scaling, DevOps integration, and stable operation

This approach allowed the solution to be built flexibly, scalably, and robustly – with a clear separation of responsibilities between system components.

Benefits & Added Value

The result of the collaboration brings both technical and operational added value for WrWKS:

Modular and Maintainable System Structure

Through the microservices architecture, multiple teams can independently take responsibility for, further develop, and operate individual services. Clear service boundaries enable genuine ownership per team, reduce dependencies, and accelerate development and release cycles while simultaneously lowering risk.

Real-Time Communication and High Scalability

Apache Kafka provides robust, distributed event pipelines – services communicate efficiently in near real-time and scale with growing demands.

Process Automation & Transparency

With Camunda BPMN, business processes are clearly modeled, orchestrated, and traceable.

Future-Proof Architecture

Kubernetes deployment, modern programming languages, and decoupled architecture ensure long-term maintainability and adaptability to future requirements.

Conclusion

The use of an event-driven microservices architecture has created a powerful, flexible system that technically strengthens WrWKS for the future – more efficient, modular, and scalable. This project demonstrates how modern software architectures help to reliably map complex business processes and create added value for operations and users.