PaedNet (part of Schulportal Hessen)
PaedNet is used within the local school network. It serves the administration of computers in the computer lab and the management of teaching scenarios with school-owned devices. The software enables, among other things, the central control of computers in the classroom (monitor lock, internet lock), the automated distribution and collection of files, the installation and updating of software on all school computers, and the generation of standardized code snippets with AI.
- Architecture redesign for existing software
- Modernization of existing software
- Code refactoring with a focus on maintainability
- Introduction of current standards (Logging, Dependency Injection)
- Training in best practices of the standards
- Establishing automated tests
- Teaching agile concepts (requirements refinement, regular reviews)
- Consulting and designing pragmatic solution approaches to reduce technical complexity
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
Central File Service
Lowell processes many documents — scanned letters, legal documents, evidence of claims, and files from consumers. The goal of the project was to provide a central file service capable of storing and serving large volumes of unstructured documents in an audit-proof manner.
- Concept and implementation of the file service, including deciding how to store metadata
- Design of the gRPC API
- Upload and download functionality in the gateway to the consumer portal
- Extension of the file service with MIME type support (required for downloads)
API-First
Lowell follows an API-First strategy. The goal was to make the API available to external processes as well. To this end, a central API was provided fully automatically and used by all services. The API is subject to strict guidelines regarding design and backwards and/or forwards compatibility depending on the use case.
- Concept and creation of a central API-First repository based on Protobuf
- Automated generation of release and pre-release versions for multiple programming languages to optimize development speed
- Concept for API versioning
- Creating APIs
- Documentation of the API
- Reviewing APIs with a primary focus on clarity, documentation, and breaking changes
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
Schleupen.CS 3.0 – Architecture and Framework
The Schleupen.CS software solution is a distributed application with numerous functional and technical components, aimed at providing a standardized and configurable software solution for the energy and water sector across different market roles. The "Architecture and Framework" team works directly with the enterprise architect and handles all cross-cutting concerns of the backend. The team's tasks involve creating cross-team best practices, design patterns, and a framework for over 100 developers, so that the architecture is implemented as consistently as possible across the many different applications.
- Development and consolidation of the application architecture
- Reducing dependencies between teams through better modularization of the framework
- Development of SOAP services for platform components
- Analysis, design, and implementation of a new deployment solution based on Puppet
- Writing and automating CoffeeScript (a JavaScript dialect) unit tests
Legacy Pub-Sub Solution
To comply with legal requirements for smart meters (intelligent electricity meters), it was necessary to establish a communication solution between Schleupen.CS 2.0 and 3.0. This had originally been excluded from the initial architecture but became necessary for business reasons.
- Concept for asynchronous communication between separate systems
- Mapping Pub/Sub queues in a database
- Implementation of generic receiver and sender solutions
Stabilization of Asynchronous Communication – Business Components
When distributed systems communicate asynchronously and messages are lost, it is very difficult to find out where they go missing. Since the previous project had shown that the errors were no longer in the platform components, the team's task was to provide solutions within the framework to support the business developers.
- Concept and implementation of the Transaction Outbox Pattern in the framework
- Documentation of the Transaction Outbox Pattern
- Training sessions on idempotency and the Transaction Outbox Pattern
Stabilization of Asynchronous Communication – Platform
When distributed systems communicate asynchronously and messages are lost, it is very difficult to find out where they go missing. The task of the project was to analyze the existing code and identify and fix weaknesses in the platform components. Solutions were also developed to increase the confidence of testers and developers in the platform components.
- Concept and implementation of the Test Message Pattern