cLean – Debt Collection Software
With the cLean project, Lowell pursued the development of a unified debt collection software for all group companies. All claims of the DACH organization were to be processed as automatically as possible in a highly available system. A key focus was determining the possible scalability of the system at certain times when large volumes of claims had to be imported. C# was the primary programming language, but individual services were implemented in Kotlin and Go.
- Architecture of the microservices system
- Defining service boundaries along business domain lines (DDD)
- Partitioning data into aggregates
- Concept and design of a case reference number readable by both humans and machines
- Concept for an immutable accounting system using Event Sourcing
- Concept and implementation of the accounting component in compliance with business rules
- Research into settlement logic in Germany and Austria
- Implementation of business logic
- Realization of search queries across distributed systems (separate service using CQRS)
- Cross-team coaching, training, and support
Migration of an On-Premise Kubernetes Cluster to Azure Cloud
Initially, services were operated in an on-premise Kubernetes cluster. The goal of the project was to migrate all services to Azure Cloud. Additionally, technologies and cloud services were evaluated, utility classes and templates were created for future development, and a CI/CD pipeline was established.
- Selection of cloud services to be used in coordination with the architect
- Agreements on future autonomy of development teams
- Review of existing code and resulting best practices
- Documentation of the Transaction Outbox Pattern, idempotency, aggregates, and other useful microservice patterns
- Utility classes for sending and receiving Protobuf business events
- Creation of the CI part of the CI/CD pipeline
- Evaluation and implementation of Azure Serverless
- Setting up infrastructure using Infrastructure as Code (IaC)
- Liveness check / readiness check for services in Kubernetes
- Creation of cron jobs in Kubernetes
- Creation of C# templates for building new services
Claim Data for the Consumer Portal
Lowell's consumer portal is a central digital service platform for individuals with outstanding claims at the debt collection agency. Lowell consists of multiple companies that are separated both organizationally and technically. Several different debt collection software systems had to be mapped onto a single API.
- Onboarding new Lowell subsidiaries
- Adaptations and extensions of the interfaces
- Definition of the API with a focus on compatibility
- Testing the interface locally, in the CI build, and in production (partially semi-automated)
- Rolling out the API with zero downtime in a Kubernetes cluster
- Analysis and resolution of production errors
- Reduction of the number of services, as the microservices had been cut too small
- Fixing security vulnerabilities and hardening API interfaces after penetration tests
- Guiding the development team to sustainably avoid identified weaknesses
- Defending the system architecture against external security auditors