Fred H.-Senior Java Architect and Developer | Domain Architect (DDD, Knowledge Systems)

Recurring problem in my own AI-assisted projects: requirements analysis, use cases, and architecture decisions can be created quickly with AI support, but remain difficult to follow and scattered across Markdown files – knowledge is lost as soon as it is no longer in the context window. arknet turns requirements engineering and architecture knowledge into structured, verifiable data instead of plain text: requirements, use cases, and architecture decisions form a consistently linked knowledge graph, traceable from requirement to architecture decision – queryable by both people and AI agents. Technically based on RDF/OWL and a custom MCP server.

Result: Working MCP daemon, Docker image published automatically to GHCR, nine hexagonal modules, eleven ADRs (including an Open-Core licensing model). Requirements engineering and Ubiquitous Language hexagons are active. Public as a Community Edition under Apache-2.0 since 07/2026 (github.com/kogn-io/arknet), together with the Claude Code plugin and GHCR image; Open-Core model.

Label: Java, Maven, RDF, RDF4J, OWL, SPARQL, Model Context Protocol, Spring AI, Docker, GitHub, Git, Claude Code, Obsidian, DDD, Hexagonal Architecture, ArchUnit, JUnit, AssertJ, Interface Development, Software Architecture, Continuous Integration, Knowledge Management

Building a fully local (on-premise) AI environment for structured extraction from emails – local language models instead of being tied to a major cloud provider. Evaluation of several local models on consumer hardware based on suitability, quality, and resource requirements; integration with my own Java application via Spring AI; securing model output through schema validation with a repair loop. Consistent use of DDD and Hexagonal Architecture.

Result: Working local environment on a used consumer GPU. Practical comparison under realistic conditions: a small model performs the extraction in around 2.5 seconds per email (warm, 14-fixture benchmark); key finding that model selection on this type of hardware is primarily a VRAM question (a considerably larger model was around seven times slower because it did not fit entirely into graphics memory). Schema validation with a repair loop catches structurally broken output. The approach is described publicly in a two-part technical article on hauschel.de.

Label: Java, Spring Boot, Spring AI, Ollama, Claude Code, Docker, Git, GitLab CI, JUnit, jMolecules, DDD, Hexagonal Architecture, arc42, GitLab, Spring, Software Architecture, Continuous Integration

Legacy analysis and modernization in an accounting product. Replacement of an existing module, refactoring of historically grown integration code, and development of a custom migration tool based on Spring Statemachine, built completely from scratch.

Coordination with various teams regarding implementation, testing, and the interface

Interface documentation

Analysis of the existing interface

Code refactoring

Architecture refactoring

Architecture and development of the migration tool

Result: Working migration tool based on Spring Statemachine, analyzed and documented interface for the successor module, and refactored integration code. Go-live after leaving the project.

Label: Java, Java Swing, Spring Boot, Spring Statemachine, ActiveMQ, SQL, Hibernate, Git, GitLab, Confluence, Jira, Scrum, Spring, Interface Development, Software Architecture

Architecture of a microservice marketplace platform, structured by the business domains organizations, solutions, orders, and offers (one separate service for each).

Analysis of an existing platform and assessment of its reusability and extensibility

Design and documentation of an architecture for a new platform (microservices)

Implementation of initial microservices to serve as templates

Integration with Keycloak, configured via the Keycloak REST API

Implementation of asynchronous task management based on ActivityPub

Result: Microservice architecture designed and documented; initial microservices implemented as templates; asynchronous task management based on ActivityPub designed and implementation started; Keycloak integration via REST API.

Label: Java, Spring Boot, Spring WebFlux, RDF, JSON-LD, Turtle, RDF4J, ActivityPub, Keycloak, Docker, Maven, Git, GitLab CI, Testcontainers, Spring Config Server, Spring JPA, Confluence, Jira, Scrum, GitFlow, REST, Spring, DDD, Hexagonal Architecture, GitLab, Interface Development, Software Architecture, Continuous Integration

Microservice that automates the rule-based placement of commercials in commercial breaks; changes can be controlled through a UI, and rule violations are reported.

Initial setup of the project, including Continuous Delivery and integration with monitoring systems in close cooperation with the Ops team

Design and development of the automated optimization of commercials in a Scrum team

Import of commercials via REST interfaces

Coordination and implementation of the REST interface for the UI

Result: Production microservice with Continuous Delivery pipeline and monitoring stack (Prometheus, Elasticsearch, Kibana); UI integration and reporting of rule violations via REST.

Label: Java, Maven, Spring Boot, REST, Postman, Docker, AWS, Git, GitLab CI, Jira, Confluence, Prometheus, Elasticsearch, Kibana, Terraform, Scrum, GitLab, Spring, Interface Development, Software Architecture, Continuous Integration

Over more than two and a half years, established a continuous approach to test automation across several consecutive projects. Started by analyzing the separate Development and Quality Assurance departments (different tools, high redundancy), then created a test framework for Development, which Quality Assurance subsequently took over and further expanded. Across the projects, quality, reporting, and collaboration between both departments improved significantly.

Analysis of the current situation in Development and QA, development of improvement proposals

Design and implementation of the test frameworks

Reporting by integrating the test framework, Jira, and HP Quality Center / HP ALM

Advising internal employees on development and architecture topics

Introduction of agile methods and Jira, optimization of reporting capabilities

Communication with a wide range of stakeholders, promoting proven methods

Result: Built a shared test framework for Development and QA that was still in use as of mid-2026 (confirmed by a colleague from the testing department in July 2026). Integrated reporting with HP Quality Center / HP ALM, introduced Jira in QA.

Label: Jenkins, Java, Groovy, JUnit, Spock, Maven, Nexus, SVN, Concordion, SoapUI, HP Quality Center, HP ALM REST API, Jira, Scrum, Confluence, Interface Development, Software Architecture, Continuous Integration

Process consulting for defining the IT incident and change management processes, supported by Jira, including the definition of a new interface between the service provider’s issue tracker and Jira. Advising management as well as Front, Middle, and Back Office on process design, Jira customization, and service provider selection.

Advising management as well as Front Office, Middle Office, and Back Office

Supporting stakeholders in designing the incident and change management processes

Supporting the adaptation of Jira to the processes and the selection of additional external service providers

Label: Jira, Scrum, Confluence, Gliffy, Enterprise Architect, Interface Development

Reorganized the runtime environment: brought 5 products across 6 environments at the hardware service provider onto a consistent setup, replacing fragmented infrastructure. Revised and standardized the build process, software structure, and development and rollout processes; updated frameworks/libraries and the database.

Analysis of the existing infrastructure, software, processes, and documentation

Planning and monitoring the new infrastructure according to the bank’s specifications

Coordinating various teams

Optimizing and documenting the software lifecycle process

Migrating existing software to new structures and frameworks or libraries

Moving redundant code into central libraries

Introducing and developing tools for monitoring the infrastructure

Label: Java, JBoss (v7.1), Oracle (v11g), Jetty, Hibernate (v4), Spring (v3.1), Maven (v3), Nagios, Jenkins, Sonar, Nexus, SVN, XML, XMLBeans, Enterprise Architect, Redhat Linux, SQL, Continuous Integration

Build reorganization for 21 web applications and 30 libraries: the existing Ant build is migrated to Maven 3, made simpler and more flexible, and integrated into Continuous Integration (Hudson), with the goal of automatically generating documentation and metrics. The migration is performed by a script that creates the Maven-compliant project structure without interrupting maintenance and further development, while preserving the SVN history.

Analysis of the existing build management

Optimization and modeling of development and build processes

Design of build management in Maven 3

Creation of an Ant migration script (svn4ant) that restructures the project according to Maven standards and preserves the SVN history

Implementation of the new build process

Automatically generated documentation and code metrics (Javadoc, Xref, PMD, FindBugs, Checkstyle, Cobertura/Code Coverage, Dependencies, Release Notes)

Quality assurance and refactoring of legacy code

Result: Reorganized build landscape (Ant → Maven 3), automated metrics, preserved SVN history.

Label: Java, Ant, Maven (v3), Hudson, Proximity, PMD, FindBugs, Checkstyle, Cobertura, SVN, Tomcat (v6), JUnit, Servlets, JSP, Struts, XML, Apache Commons, Continuous Integration

Cross-product-category redesign of a highly complex logistics platform that had grown over many years: the existing PL/SQL solution is replaced by a message-based architecture based on Enterprise Integration Patterns (Gregor Hohpe). The goal is to modularize the platform, reduce release errors, and create a flexible foundation for future requirements.

Design of the cross-product-category logistics redesign

Replacement of the PL/SQL logic (extraction from the order management system, delivery note to the logistics service provider) with a messaging architecture based on EIP

Documentation of the architecture using Gregor Hohpe's pattern symbols to establish a link to the literature

Result: Logistics platform converted from PL/SQL to a message-based architecture (EIP).

Label: Java (v1.4), Maven (v2), Archiva, SVN, Web Services, WSDL, XSD, XML, Mantis, Oracle OC4J, Confluence, Enterprise Architect, Enterprise Integration Patterns, Share Point, UML, SQL, Oracle, Interface Development, Software Architecture

Expanded the installation service into a "full-service installation concept": an installer application (installer CD) guides customers or service technicians through the installation and covers registration, login, ordering and downloading the security package, product information, and setting up and ordering messaging and hosting.

Replaced the PHP service with a Java implementation

Created a new library for authentication and authorization that will gradually replace the difficult-to-maintain legacy code and is also offered as a web service

Extracted the password validation logic from the legacy code and made it reusable for the existing and new library

Connected existing, partly external web services

Result: Replaced the PHP service with a reusable Java service with an authentication library.

Label: Java (v1.4), Maven (v2), Archiva, SVN, Web Services, WSDL, XSD, XML, Apache Commons, Spring, Clear Quest, Tomcat (v5), Oracle OC4J, Confluence, Enterprise Architect, UML, Interface Development, Software Architecture

Optimized the development process in a heterogeneous IT landscape that had grown over many years, with development distributed across multiple teams. As architect and link between the project stakeholders, brought the technology up to date and prepared innovations that delivered both technical and business benefits; led the Middleware team for agent and customer portals.

Established a property management process in which all properties are maintained centrally and divided into .zip files for each environment during the build, with a consistent and interchangeable access mechanism using Spring and Apache commons-config

Introduced Maven 2 and the associated build process

Information portal based on a metamodel (environments, system layouts, artifacts, releases) – displays Maven artifacts with versions, release notes, metrics, documentation, and target/current layouts, with navigation from the environment down to the source code

Introduced a Confluence wiki to document software artifacts

Introduced state-of-the-art technologies such as Axis 2 and Spring

Model-driven software development using a self-developed DSL for describing interfaces at an abstract level; a generator uses templates to create complete technical software components from them (including a WSDL generator), allowing developers to focus on business logic

Result: Modernized the build and toolchain (Maven 2, custom DSL with xtext/xpand, information portal with metamodel).

Label: Java (v1.4), Ant, Maven (v2), Archiva, SVN, CVS, Axis (v1), Axis (v2), Web Services, WSDL, XSD, XML, Servlets, JSP, Struts, Spring, Spring LDAP, OpenArchitectureWare, xtext, xpand, Tomcat (v5), Confluence, Enterprise Architect, UML, Apache Commons, Clear Quest, Quartz, Interface Development, Software Architecture, Knowledge Management

Further development of web-based customer advisory software in a multi-tier architecture: the web application records and evaluates the customer's financial situation and offers products; together with other channels, it accesses the same middleware.

Analyzed the current state (architecture review, assessment of the specification, evaluation of the development approach and tests) and made recommendations for the next steps

Developed an alternative architecture proposal

Advised on tool selection and recommended the development environment

Provided advice on industry- and application-specific questions

Contributed to taking over the web application (especially the middleware connection)

Represented the technical perspective in meetings with the major bank

Initiated closer cooperation with the team of the parallel project

Result: Architecture review and alternative proposal; contributed to taking over the web application (middleware connection).

Label: Java, CVS, Java (v1.3), Tomcat (v4.1), Struts, Apache Commons, Enterprise Architect, Software Architecture

The bank's historically evolved source code organization no longer met requirements and was restructured according to the latest JBF guidelines; special feature: the change had to be completed in one day.

Analysis of the source code organization

Refactoring planning

Development of guidelines for the migration and supervision of the source code migration within CVS

Refactoring, testing, and commissioning

Label: Java, CVS, Java (v1.3), JBF (v4.15)

Modernization of the loan processing application (continuation of the 2001 project): brought up to date with the latest version of the Java Banking Framework and replaced the previous HTML interface with a JBF Swing client launched via Web Start. The three-tier application (client, server, backend) communicates with the Lotus Notes backend via XML in the server layer.

Technical analysis of the interface between client and server

Interface design

Design and implementation of the server layer

Label: Java, CVS, Java (v1.3), Tomcat, JBF (v4), XML, HTML, Interface Development

Replacement of an existing loan processing application with a future-proof application using Java, Servlets, and JBF, including an import interface and integration of a complex host application through standard patterns (GoF).

Technical analysis

Design of an import interface

Design and implementation of the integration of a complex host application using standard patterns (GoF)

Label: Java, Java (v1.1), JBF (v3), Servlets, CVS, Interface Development

Enhancement of the online presence and migration of the financial portal from Microsoft COM to J2EE; the tasks were carried out within a complex project environment and focused on specific topics.

Requirements analysis: requirements catalog created together with the business department and web designer, technical consulting, reporting to the overall project manager, team leadership

Project planning and organization: contribution to the comprehensive technical project plan, scheduling and resource planning, onboarding of team members, communication between the end customer, client, and subcontractors

Integration of a host system into the new portal: analysis of the existing integration, design of a new J2EE-compliant solution, onboarding of the development team, management of the development of a test framework

Integration of a market data provider through XML: design and implementation of an XML interface in Java on a J2EE-compliant platform (Enterprise JavaBeans) through to the web tier

Integration of client and server: connection of static HTML pages to the middleware through JSPs, creation of test JSPs

Result: Financial portal migrated from MS COM to J2EE; J2EE-compliant host integration designed; XML interface to the market data provider designed and implemented; securities sub-team established and led.

Label: Java, TogetherJ (v4), Java (v1.2), Tomcat, BEA Weblogic (v5.1), abaXX ebs, abaXX JSP Framework, PVCS (v6.5), Oracle (v8i), HTML, JSP, UML, XML, Interface Development

A Java application was to transfer program schedule data from a television broadcaster from an XML file to a database.

Design and implementation of the Java application

Graphical display of the data using HiGrid classes (KL-Group)

Testing, maintenance, and enhancement

Label: Java, Java Swing, JDBC, XML, Informix