Jens Rehsack - Technical Product Owner

Recommended expert

Kerpen, Germany

Experience

May 2025 - Present

9 months

Technical Product Owner

App Development

Developed a mobile app to slow down the progression of dementia
Coordinated software development (TPO – Technical Product Owner)
Agile requirements management (agile requirements engineering)
Prioritized tasks in consultation with stakeholders
Stakeholder management
Documented and managed the software architecture
Conducted PoCs for technology decisions
Documentation as Code
docToolchain, arc42, req42, aim42, tpo42, C4 model, Archimate
ADR, Architecture Decision Records
Docker
Pre-Commit, Conventional Commits, Semantic Versioning
Liberating Structures, Agile Principles, Holacracy, Sociocracy 3.0
Mobile frameworks
AI development interfaces, LLM
Cordova, Unity
Google Gemini, OpenAI, Character.AI
Prompt development

Jun 2024 - Present

1 year 8 months

Technical Product Owner

Test & Measurement Technology

Delivered the software platform for the next generation of inspection technology
Coordinated software development (TPO – Technical Product Owner)
Agile requirements management (agile requirements engineering)
Prioritized tasks in consultation with stakeholders
Stakeholder management
Documented and managed the software architecture
Guided the team to self-organization (agile coaching)
Led agile ceremonies
Prepared and facilitated retrospectives
Software supply chain management
Documentation as Code
docToolchain, arc42, req42, aim42, tpo42, C4 model, Archimate
ADR, Architecture Decision Records
Confluence, Jira, ConceptBoard
Bitbucket, GitLab
Docker, Yocto, SDK
Pre-Commit, Conventional Commits, Semantic Versioning
Kanban, regular status meetings, moderation techniques
Liberating Structures, Agile Principles, Holacracy, Sociocracy 3.0
Agile ceremonies (retrospectives, refinements, demonstrations)
QA metrics
SBOM, Software Bill of Materials
VISCA protocol
Jira management (administration)
Hardware architecture

May 2024 - Mar 2025

11 months

Consultant / Konzeption

Energy Industry

Built a continuous integration platform for distributed product development
Consulting, design, and development of platform software
Advised on the transformation from manual to automated integration
Git coaching
Pair/crowd programming
Agile coach support
Guided team self-organization (agile coaching)
Led agile ceremonies
Prepared "Agile Snacks"
Product Owner support
GitHub Actions, GitHub Workflows
Documentation as Code
docToolchain, arc42, C4 model, Archimate
ADR, Architecture Decision Records
Confluence, Jira, ConceptBoard
Liberating Structures, Agile Principles, Holacracy, Sociocracy 3.0
Docker, Podman
Azure Cloud
Pre-Commit, Conventional Commits, Semantic Versioning
BOM, SBOM
HiL, hardware-in-the-loop simulation
SiL, software-in-the-loop simulation
SAFe, LIFe
Agile transformation

Aug 2023 - Apr 2024

9 months

Consultant / Konzeption

Energy Industry

Yocto / Linux platform development
Consulting, design, and development of platform software using C++ (C++17, C++20) and Yocto
Further development of the CI pipeline and automated regression tests
Further development of GitHub CI/CD workflows and pipelines
Creating and maintaining concepts and guides
Agile implementation of EPICs (story creation, stakeholder management)
Supporting agile transformation ("Agile Snacks")
Agile coach support, facilitation, Agile Manifesto
Yocto
arc42
Scrum, Kanban, moderation techniques
Agile Snacks
Liberating Structures, Holacracy, Sociocracy 3.0
GitHub, GitHub pipelines, GitHub Workflows, GitHub Actions
Docker, Docker containers, Podman, Toolbx
ADR, Architecture Decision Records
Confluence, Jira, ConceptBoard
Agile architecture principles, agile requirements development (aim42)
C++17, C++20
CMake, CMake modules, CMake extensions
Unit testing, GTest (Google Test), code coverage tests
Pre-Commit, Conventional Commits, Semantic Versioning
SBOM
Maintained cloud IoT gateways in Yocto
Coverity, Tics
Python Poetry
Azure Cloud
Polarion
Robot testing
SPES, SysML, UML2

Jul 2022 - Oct 2022

4 months

System architect for embedded product development

Engineering

System architect for embedded product development
Analyzed and evaluated existing architecture
Developed architecture optimizations
Developed implementation optimizations
Identified gaps in knowledge management
Reverse engineering
Agile ceremonies
arc42, PlantUML, C4 model
Bitbucket, Confluence, Jira
Agile architecture principles
doctoolchain, Asciidoctor
PlantUML standard library
Connecting cloud IoT platforms with Yocto (MQTT, Kafka, Azure)
Connecting energy industry gateways to smart home gateways (e.g., Matter)
Docker, Kubernetes, K8s, ArgoCD, Ansible 2

Feb 2022 - Mar 2023

1 year 2 months

System Architect for Product Organization

Energy Industry

System architect for product organization
Creation of architecture documentation using arc42, C4 model
Development and introduction of guardrails (e.g. architecture manifesto)
Coaching developer teams in the use of best practices
Building communities of practice (architecture) – guilds in the Spotify model
Facilitating agile workshops
Facilitating architecture decisions and community of practice
Creating PoCs for ongoing architecture documentation
Integration into knowledge management
arc42
ADR, Architecture Decision Records
PlantUML, C4, ArchiMate
GitLab, GitLab pipelines
Confluence, Jira, ConceptBoard
agile requirements management (e.g. aim42)
agile management, Spotify model
agile architecture principles
Liberating Structures, Sociocracy 3.0
doctoolchain, Asciidoctor
leadership culture, servant leadership
facilitation techniques, e.g. tension-based work
connecting cloud IoT platforms with Yocto (MQTT, Kafka, Azure)
Azure cloud
cloud-to-cloud connections
energy-gateway connection to smart home gateway (e.g. Matter)
Docker, Kubernetes, K8s, ArgoCD, Ansible2
InfluxDB, Timescale, Influx cloud infrastructure
cloud RDBMS

Jun 2021 - Dec 2021

7 months

Engineer / Architect Container Platform – Private Cloud Technology

Public Sector Service Provider

Engineer/Architect for container platform – private cloud technology
Capturing & documenting architecture decisions using arc42
PoC for required services in Tanzu Kubernetes clusters
Designing services following cloud-native principles
Agile consulting, support for agile transformation
legacy communication
infrastructure architecture
K8s, cloud-native
requirements analysis
GitLab, GitLab Runner
secret management, ACME (Automated Certificate Management Environment)
GitOps
SAFe / agile transformation
Helm charts
SAP Jam
Let's Encrypt
step-ca
Nexus OSS
repository manager
supply chain management
Helm chart
TOGAF
HashiCorp Vagrant, Packer & Vault

May 2021 - May 2021

1 month

Software Development / Linux Kernel Troubleshooting

Measurement Equipment Manufacturer

Troubleshooting in the customer-specific Linux kernel
Analyzing the existing solution and matching it with application requirements
Capturing and documenting tacit knowledge
Implementing missing features and fixing issues through kernel updates
Advising on ongoing maintenance of embedded systems
Participating in Scrum ceremonies
Linux kernel
requirements analysis
system architecture
Xilinx ZYNQ 7020
embedded Debian environments
Jenkins
OpenVPN

Dec 2020 - Jun 2021

7 months

Architecture and Implementation Support for Microservice Architecture

Leasing Consulting

Architecture and implementation support for introducing a microservice architecture
Analyzing the existing solution and matching it with application requirements
Team grooming to capture tacit knowledge
Capturing & documenting requirements using arc42
Creating specifications in Confluence & draw.io
Reviewing requirements & specifications with the team and the architecture board
Supporting the creation of CI/CD based development workflows
Coaching on building a company-wide software architecture
object-oriented analysis & design
requirements analysis / requirements engineering
object-oriented design
system architecture
management consulting
creating decision templates
Spring Boot
Jenkins, GitLab
OpenVPN

Nov 2019 - Mar 2021

1 year 5 months

Consulting and Support for Embedded Solutions Migration

Measurement Technology Supplier for Aerospace

Consulting and support for migrating embedded solutions from Buildroot to Yocto Linux
Migrating from Subversion to Git
Architecture of a reliably updatable operating system with Yocto Linux
Capturing & documenting requirements and creating specifications
Maintaining and updating the BSP (u-boot, Linux kernel (QorIQ), RCW, TF-A (ATF))
Designing concepts for fast & secure startup and reliable updates
Supporting agile transformation, agile coach consulting
Integrating legacy components
Administering Unix infrastructure components (DNS, DHCP, VLAN) as well as GitLab, Mattermost
NXP QorIQ, Layerscape platform
Yocto, OpenEmbedded
extensible SDK
s6 startup
system architecture, infrastructure architecture
legacy migration
GitLab, GitLab CI, GitOps
Mattermost
TOGAF
Buildroot
Subversion
creating decision templates
OpenVPN

Jul 2019 - Jan 2020

7 months

Consulting and support for migrating embedded solutions

System house for traffic control systems

Consulting and support for migrating embedded solutions from Windows CE to Yocto Linux
Analyzing the existing solution and matching it with the application requirements on the current device generation
Gathering requirements
Conducting a Yocto workshop
Documenting requirements
Creating specifications
Reviewing requirements & specifications with the team and in the architecture board
NXP i.MX6, phyCard
Yocto, Open-Embedded
eSDK
VNC
Requirements engineering
Architecture
Scrum of Scrum
Windows CE
Subversion
Management consulting
Preparing decision papers

Feb 2019 - May 2019

4 months

Software development for a mobile ECU solution

Automotive supplier

Creating a mobile solution for lab and warehouse updates of control units
Gathering requirements
Planning tasks by requirement in Polarion
Analyzing real-time controls and protocol implementations
Developing update software for the respective chips
Integrating the solutions into an automated overall system
Stakeholder management
Agile work using selected Scrum tools
Programmable Realtime Unit (PRU, PRUSS)
USB device management
SREC, S-Hex firmware updates
libusb
RS232
SanCloud BeagleBone Enhanced, BeagleBone Black, Pinmux
BeagleBoard Debian
Single Wire Debug
Manual Debian packaging
GitLab, Jenkins
Yocto
Valens VA6000
Microchip USB4916
NXP S9KEA

Dec 2018 - Feb 2019

3 months

Software development for embedded Linux operating system platform

Building automation

Creating a lab variant of the embedded Linux operating system platform with cloud support
Porting IEC 61499 compatible embedded software to an embedded industrial PC for cloud integration
Packaging the software and supporting components
Creating Docker containers
Basic operating concept and cloud concept for Composer and Kubernetes
Test scenarios to verify real-time capability
Documenting the setup
Reviewing concepts and sources delivered by third parties
Docker, Docker Compose
Software-defined networking
Cross-compilation, cross-compile SDK
Kata containers
TCP, UDP, Ethernet
Perl6 / Raku
crosstools-NG
LLVM, Clang
Jira, Confluence, Bitbucket
GitLab, GitHub
IEC 61499, IEC 61131
BACnet, CAN-BUS, LON, DALI, FBUS, SBUS, MBUS
EnOcean, ZigBee, KNX
Kafka, Kubernetes
Real-time capability
RS232, RS485

Jun 2018 - Oct 2018

5 months

Software development for embedded Linux operating system platform

Biotechnology

Creating an embedded Linux operating system platform for machines produced by the company
Designing a Yocto/OpenEmbedded-based distribution set for various client devices
Implementing a distribution with Yocto for the next device planned for release
Requirements analysis according to medical standards
Kernel configuration to the latest standards via the Kernel Meta-Framework
Requirements analysis for the needed infrastructure when moving development from Windows to Linux and cross-compilation
Creating and maintaining an SDK
Analyzing optimal CAN host adapters
Maintaining kernel drivers from various CAN hardware suppliers
Developing a network concept to separate development, test (IT), and lab (medical)
Yocto Sumo, Yocto Thud
Intel Bay Trail SoC
Peak CAN, Apacer CAN, MCP CAN
Ethernet tagging, VLAN
Scrum
Bitbucket, Jira, Confluence
Polarion
Cross-compilation, cross-compile SDK
Python 3 updates
gRPC, Protobuf
Industrial PC
Linux 4.14
UEFI

May 2018 - Jul 2018

3 months

Consulting / coaching for code quality

Leasing software

Consulting/coaching to improve code quality
Designing quality control processes based on stakeholder requirements
Improving workflow integration into existing Scrum processes
Coaching skills in working with Git, Git processes, and GitHub
Analysis of existing workflows
Identifying current quality issues
Pinpointing gaps in existing processes
Developing comprehensive workflows including quality control stages
Visual representation of workflows
Creating a cheat sheet for the git commands needed for work
Preparing a report on further improvement opportunities
Linux extension for Windows 10
Git, GitHub, Jira, Confluence
Scrum
LaTeX
Redmine
Windows 10
Dia

Apr 2016 - Dec 2018

2 years 9 months

System Architect Platform Inventory / CMDB

Logistics / Communication

Designed and implemented platform inventory
Created a CMDB for a live platform
Migrated platform administration from manual to automated processes in the data center
Designed automated processes for continuous maintenance
Created a CMDB extension for an additional processing system
Integrated extensions into the CMDB and platform inventory
Requirements analysis for semi-automated administration of the existing platform and infrastructure based on ITIL
Designed milestones for step-by-step data collection and automation
Captured atomic configuration items
Designed and built a Configuration Management Database
Designed and supported platform migration from CentOS 5 (physical) to CentOS 6 (virtual machines)
Designed a RESTful API to query configuration items from the CMDB
Designed a RESTful API to apply change requests against the CMDB
Introduced agile methods from the Scrum toolkit for project management in Jira, following Kanban-based operations
Documented subprojects and guides in Confluence
Planned migration projects
Designed and planned a cloud infrastructure with managed InfiniBand & Gigabit Ethernet
Performed performance analysis of the NetApp cluster
Perl, Perlbrew, Perl5 toolchain
CentOS 5, 6
ITIL, CMDB
DBI, SQLite 3, Oracle 12
Moo, MooX, AnyData2, CPAN
JSON, YAML
git, Bitbucket, Jira, Confluence
Scrum
GnuPG
GitOps
Inventory (Ethernet/IP, filesystem, applications, packages)
Puppet, Hiera
IT baseline protection
Postfix
HAProxy
OpenNebula
VMware ESX
Unicode
TeamCity
OpenVPN

Jan 2015 - Present

11 years 1 month

Open-Source / Community Engagement

The Linux Foundation / Yocto Project

Adding, updating, and fixing packages for OE-Core, OpenEmbedded, and Java, especially Perl5 (OE-Core), Samba (OpenEmbedded: meta-networking), Nginx (OpenEmbedded: meta-webserver), and OpenJDK 8 (meta-java)
Maintained a custom layer for Perl modules as offered on CPAN (meta-cpan)
Maintained layers for systemd replacements (meta-sysinit)
Maintained a layer for provisioning and updates, e.g. OTAU (meta-prd-flash)
Ported and packaged OpenJDK 8
Safety, reliable boot system, read-only filesystem
Developed and adapted BSPs (Board Support Packages)
Developed an SDN for workshops and development/integration/test stages
Yocto, OpenEmbedded
git, Mercurial, Subversion
Patch management
Patch review
Bootloader
Docker, Linux Containers (LXC), QEMU, KVM, VirtualBox, VMware, Vagrant
Managed switches, single-tagged Ethernet VLANs
LLVM 3.5, LLVM MCJIT
Java 8 HotSpot, Java 8 Shark (Zero/Shark)
Samba 4 (incl. waf), dnsmasq, systemd

Oct 2014 - Jul 2015

10 months

Modernizing provisioning components

Telecommunications / Provisioning

Modernized existing provisioning components
Created an operations concept
Agile transformation
Designed and implemented software components based on requirements and existing APIs
Developed deployment strategies
Module testing & test automation
Agile operating models (ITIL)
Kanban, ITIL
Perl, Perlbrew, Perl5 toolchain
RHEL 6, Solaris 10
DBI, Oracle 11, SQLite 3
Moo, MooX, AnyData2
SFTP
git
AngularJS
CableMaster
NetApp

Jun 2014 - Feb 2016

1 year 9 months

Embedded Linux operating system software development

Home Automation / Smart Home

Designed and implemented a fully updatable Linux-based operating system for embedded home automation to prevent security issues for end users
Analyzed available frameworks for cross-compiling custom Linux distributions with a focus on long-term update availability
Assembled the distribution for the home automation system
Integrated and system-tested board support packages (BSPs)
Modularized images for optional installation of Kodi/media players
Designed full system updates using a rescue system
Designed update strategies for legacy devices in the field
Release management
Provided technical support for application development
Refactored BSPs to harmonize interfaces across all platforms
Agile transformation: introduced Kanban evolving to Scrum
Agile coach, established the Product Owner role
Migrated from Subversion to git (GitHub, Bitbucket)
Designed & implemented a software-defined network for development (IT), testing (IT), testing (business unit), production (factory), and goods receipt (factory)
Administered build environment (OpenZFS on Ubuntu)
Yocto, OpenEmbedded
System security & reliability
Linux 3.0, 3.10, 3.14, 4.1
Freescale i.MX6, Globalscale GuruPlug, Marvell Kirkwood
Cross-compilation
Packaging Perl, Java (OpenJDK), Collectd, RRDTool, CPAN modules, Google V8
libstatgrab, daemontools, daemontools-encore
Moo, MooX::ConfigFromFile, IO::Async, Dancer2
Wireshark / tcpdump
git, Mercurial, Subversion, nginx
Kanban, Scrum
Jenkins
Linux firewall (nftables)
RAID-Z2
ZFS performance tuning
Network segmentation with VLANs (separate developer networks), single-tagged Ethernet
Managed networks
ARM assembly, NEON
LLVM, MCJIT
ARMv7 optimizations, ARM5-TE cross-compile fixes, ARM5 assembly, Thumb
U-Boot (bootloader)
Z-Wave, DuoFern
Jira, Confluence, Bitbucket, GitHub
GCC 4.8, 4.9, 5.2
Ant, Maven, Groovy
Scrum Master
GPG, OpenVPN

Oct 2013 - Apr 2014

7 months

Software development IPv4/IPv6/IPSec components

Telecommunications / Embedded

Developed IPv4/IPv6/IPSec components in the LTE transport environment (routers)
Designed and implemented software components based on requirements
Designed communication layers between Linux and bare-metal SE units
Linux kernel drivers
Module testing & test automation
Set up test infrastructure for module and manual tests (including remote debugger and Lauterbach)
Renewed the deployment platform after hardware failure using ZFS
Architected updated hardware acceleration features for IPv6
Architecture consulting for cross-compile toolchain
Lauterbach debugger
Cross-compilation using third-party SDK
IPv4, IPv6
IPSec (StrongSwan, Kame)
g++ 4.2, 4.3, 4.7
Scrum, daily standup using Kanban
VNC
eMake
Subversion, git
Linux From Scratch (LFS)
Ixia network tests
Cisco
Wireshark / tcpdump
Routing
Perl
Zettabyte File System (ZFS), OpenZFS
Managed networks
Single-tagged Ethernet, double-tagged Ethernet
Soft switch, software-defined network
Bare-metal programming
Virtual compile nodes (VMware)
Scrum Master
PkgSrc
Lua

Jul 2013 - Jul 2013

1 month

SNMP Agent Development

Rail / Embedded

Development of an SNMP agent for use on railway tracks
MIB design and implementation
Programming of sensor measurements
Test and acceptance support
Technical documentation
Debian Linux, µCLinux
net-snmp
gcc
Cross-compilation
embedded Linux (uClinux / µCLinux)
Ethernet control

Jan 2013 - Jun 2013

6 months

Porting Existing Services

Government Agency

Porting existing services
Porting existing applications to SLES 11
Debugging and optimization
SLES 11
Adabas 5.7
AutoConf/AutoMake
GNU C Compiler
Micro Focus COBOL
OpenCOBOL
XML-RPC
Character conversion / Unicode interoperability
Shared Memory, IPC
Synergy (CM / Rational)
Kanban
COBOL
BS2000

Dec 2012 - Jan 2013

2 months

Web Application Development

Marketing Agency

Development of a web application
Taking over an existing, unfinished application
Adjusting components to customer needs
Database optimization
RHEL (Red Hat Enterprise Linux) 6.1
MySQL 5.1
Apache Web Server 2.1

Feb 2012 - Dec 2012

11 months

Integration and Operations Team Support

Telecommunications Provider

Supporting the integration and operations team
Developing Perl scripts to support the operation and monitoring of applications in the data center
Developing Nagios plugins to replace end-of-life products and monitor new applications
Performance analysis of operated applications
RESTful API for various web frontends using MySQL, PostgreSQL, and SQLite databases
Operating Smart-SNMPd including MongoDB plugins (C++, Linux/Solaris)
Statistical analysis of distributed log files (Perl)
Configuration and operation of Debian Linux including Nagios, Jenkins, PostgreSQL, MySQL, OpenVZ, and Xen
Monitoring
Performance optimization
Developing end-to-end tests for location services in C & Perl (Swig)
Multi-stage application for automatic position alignment with SUPL on Linux using oFono
D-Bus communication with USB test hardware
Debian 6 (Squeeze), Solaris 10 (x86), MacOS X 10.8 (Mountain Lion)
VMware ESX, Xen, VirtualBox
Nagios, Smart-SNMPd, libstatgrab
Perl (Module::Build, DBIx::Class, Moose, Moo, DBI, SQL::Statement, cpanminus, JSON, Dancer, Net::DBus, Dist::Zilla, Devel::NYTProf, DBD::CSV)
Swig
pkgsrc
Kanban
gcc, g++ (3.4, 4.4, 4.7)
CVS, Subversion, git, fossil (SCM)
D-Bus
MySQL 5.1/5.5, SQLite 3, PostgreSQL 9.1
ASN.1 (SUPL, SNMP)
GSM, UMTS, LTE
Network monitoring (Ethernet, IP, NGN)
Application monitoring
glib/gobject
oFono
S7
Daemontools (supervision, system startup)
MongoDB
HPE iLO

Nov 2011 - Jan 2012

3 months

Linux Operations Support

IT Service Provider for a Retail Corporation

Supporting the Linux operations team in the data center
Developing Perl scripts to support Linux administration
Installing third-party applications (e.g., Tivoli Monitoring Agent)
Designing a DBIx::Class-based database for managing installations
Interfacing with the systems management team
Maintenance of Subversion installations
Documentation in MediaWiki
Red Hat Enterprise Linux 5, 6
Red Hat Network Add-Ons (Satellite, HA cluster)
Open Cluster Framework
Tivoli Monitoring
Perl (Module::Build, Satellite API, DOM::XML)
dmidecode, systool
Kerberos
XIV, EMC, IBM Storage Cluster
Tivoli Storage Manager
Multipath
VMware ESX, KVM

Oct 2011 - Nov 2011

2 months

Multi-Platform Compilation

Software Development Company

Multi-platform compilation of application components
Setup / configuration of build environments for Solaris, AIX & HP-UX
Compiling required open-source components (apr, apr-util, log4cxx, boost, gzip, bzip2, 7zip)
Compiling the application components
Support for internal developers
Bug fixing
HP-UX 11.31 (IA64)
Solaris 10 (SPARC)
AIX 6.1
C++, shell scripting
GNU Compiler Collection 4.2 (gcc 4)
Standard Template Library (STL), Boost
IBM VisualAge for C++ (XLC) 11.1
Oracle/Sun C++ Compiler (SunPro) 12.2
Apache C/C++ libraries (apr, apr-util, log4cxx)

Aug 2010 - Sep 2011

1 year 2 months

Monitoring and 3rd-Level Support for Unix Operations

IT service provider for an automotive manufacturer

Support for OS and application monitoring in the data center
3rd-level support for Unix operations
Development of a multi-threaded SNMPv3 server for Unix and Linux in C++
Software architecture and design using the Booch method with UML
Design and further development of the Management Information Base (MIB)
Implementation of a proof of concept for the SNMP server
Implementation of necessary statistics collectors (as a library) for Linux, Solaris, AIX and HP-UX in C
Porting the C++ libraries snmp++ and agent++ to various Unix environments using autotools
Development of SNMP plugins for Nagios in C++
Development of SNMP daemon plugins for additional application monitoring in Perl
Creation of automated tests in C++ and Perl
Packaging software for systems management using epm
Creation and maintenance of CFEngine rules
Debugging (trace analysis, gdb, valgrind, ...)
Documentation (LaTeX, Doxygen)
Data center operations
HP-UX 11.11-11.31 (HP PA-RISC & IA64)
SUSE Linux Enterprise Server 9-11
Solaris 8-10 (SPARC & x86)
Operating system and application virtualization
AIX 5.2-6.1
Programming languages C, C++, Perl, shell scripting
GNU Compiler Collection 4.2 (gcc 4)
CFEngine, Red Hat Package Manager (rpm – SLES, RHEL), Licensed Program Products (lpp, bff – AIX), Software Bundles (swinstall – HP-UX) & Packages (pkg – Solaris)
Standard Template Library (STL), Boost
snmp++, agent++
libstatgrab, POSIX system API, vendor-specific system API
libjson, libConfuse
autoconf, automake (GNU Autotools)
Ethernet parameters, controller parameters, disk parameters
Kerberos, LDAP, NDS
Perl5 (5.8)

May 2010 - Jul 2010

3 months

Redesign Database Driver

Open-Source / CPAN

Redesign of the pure-Perl database driver DBD::File
Requirements analysis
Software architecture and design with UML
Implementation of the new design in Perl5 (with Perl 5.8 compatibility)
Documentation of the API and extension possibilities in POD
Perl DBI & DBD interface
libdbm, GNU DB, BerkeleyDB
JSON, YAML (mapping multi-column tables to key/value structures)
PostgreSQL (as a reference)
SQL::Statement vs. DBI::DBD::SQL::Nano
Introduction of an abstraction layer (DBI::DBD::SqlEngine) for pure-Perl DBDs

Mar 2010 - Apr 2010

2 months

CRM Application Migration

ISP / Cable Provider

Migration of a CRM application
Provision of a Perl 5.10 environment including multithreading on HP-UX 11.23
Provision of DBI/DBD modules for database access
Performance optimization (databases, Perl)
Multithread programming with Perl
HP-UX 11.23
GNU Compiler Collection 4.2 (gcc 4)
Perl 5.10
DB2 8.5, Oracle 10i, PostgreSQL 8.3
Log::Log4perl
DBI 1.609, DBD::DB2, DBD::Oracle
Profiling with Devel::NYTProf

Oct 2009 - Dec 2009

3 months

Böblingen, Germany

Porting Backup Solution

IBM Lab Böblingen

Porting the backup solution Tivoli Storage FlashCopy Manager from AIX to Linux & Solaris
Refactoring the Makefiles into a more flexible structure (OS-specific compiler adjustments & flags)
Porting & integrating OpenPegasus, ICU and OpenSSL in the latest version
Setting up machines with the target platform (SLES 10, Solaris 10)
Developing a C++ interface to Python (based on the Python C API)
Designing new software components in UML
AIX 5.3 TL5, Solaris 10, SLES 10, SLES 11, RHEL 5, RHEL 6, VMware Server
IBM C/C++ Compiler for AIX 8.0, IBM C/C++ Compiler for AIX 9.0
Sun Studio C/C++ 12.1
GNU Compiler Collection 4.1 (gcc 4)
GNU make 3.74, GNU make 3.8
Perl 5.8
Agile Development
Tivoli Storage FlashCopy Manager
ksh scripts for auto-build
Unit tests
Ubuntu Karmic
Scrum
Python 2.6 C API
Managed network
Veritas Cluster Manager
Oracle Backup (via backint), SAP Backup, DB2 Backup
Installing Oracle and DB2 instances
Linux LVM2, Solaris ZFS, Veritas Volume Manager, AIX LVM
Python 2.6
SAN storage: XIV, DS8000 cluster, SVC
CMVC

May 2007 - Sep 2009

2 years 5 months

Lead Developer Data Center Automation

IT service provider for a chemical corporation

Data center automation in HACMP and SAP environments (concept/design, architecture & programming)
Developing core functions used by all scripts
Implementing build, test and release management via RPM and tagging using a CVS interface (ITIL requirement)
Designing needed features to bring in additional team support (lead development)
Creating applications for configuration and operational tasks of SAP, Uniq, Oracle and HACMP
Managing virtual machines (Linux) and logical partitions (LPAR, AIX)
Perl 5.8, Perl 5.10, CPAN
Red Hat Enterprise Linux 4 (RHEL4), Red Hat Enterprise Linux 5 (RHEL5), gcc 3.4
Operating Linux server farms, virtualization using shared-root images
AIX 5.2, 5.3, HACMP 5.4, xlC 10, LPAR/WPAR/CoD
Template::Toolkit, SQL::Statement, DBI, DBD::Oracle, ...
Eclipse 3.3, Eclipse 3.4, Eclipse 3.5
EPIC (Eclipse Perl Integration), ActiveState Perl, SQL Explorer, Mylyn, Subclipse
Bugzilla 3, CVS, Subversion 1.5 and Subversion 1.6 (svn)
pkgsrc for own Perl distribution
Rational Software Architect 7.5
XS (C interface for Perl) for speeding up Perl modules and connecting C/C++ libraries
Packaging/converting software packages using pkg, rpm and lpp (installp, bff) and ppd
Generating reports using Template::Toolkit & LaTeX, Template::Toolkit plugins
Single sign-on with Kerberos
SAP Basis administration 4.6, 6.4, 7.0 (backup with backint and rman, virtualization, distributed systems, monitoring, SLA (Service Level Agreement), ...) for R/3 ABAP systems, J2EE and dual-stack instances
Oracle 10 under SAP
Oracle GRID, Oracle RAC
NetApp cluster (NAS)/HP StorageWorks XP (SAN) administration for SAP/Oracle installations
Virtualizing Linux guests with VMware, KVM and Xen (proof of concept)
SAP NetWeaver (with sapnwrfc) for managing administrative SAP users

Jan 2007 - Present

19 years 1 month

Open-Source / Community Engagement

The NetBSD Foundation

Adding and updating 3rd party applications in the pkgsrc environment for AIX, Linux, Windows, Solaris, HP-UX, Mac OS X (Darwin), FreeBSD and NetBSD
PkgSrc, packaging
Package conversion
cvs, subversion, git, mercurial, fossil
Compiling open source software on various operating systems
Security patch management, security risk management
Vulnerability management
IBM XL C/C++ v10/v11 for AIX
Oracle Studio 12.1 for Solaris (Sun Studio)
GNU Compiler Collection 4.x (gcc/g++ 4.2-4.9, 5.2, 6.0, 7.0, 8.0, 11.0, 13.0)
Xcode 3.3, 4.5, 5.1, 6.1, 7.3 (Clang, LLVM), 9.1, 10.1
GNU make, BSD make, GNU Autotools (autoconf, automake, libtool, ...)
Solaris 8-11 (OpenSolaris, Solaris Express), AIX, HP-UX, NetBSD, FreeBSD, Mac OS X, Debian (Lenny, Squeeze), SuSE Linux (SLES, SLED), Red Hat Enterprise Linux
Porting open-source software to AIX, HP-UX, NetBSD, FreeBSD and Mac OS X
Intel x86, x86_64, amd64, Sparc, PowerPC, MIPS, ARM, DEC Alpha
Deploy management
graphviz

Jan 2007 - Dec 2021

15 years

Open-Source / Community Engagement

Perl Comprehensive Archive Network (CPAN)

Maintaining and further developing Perl modules
API documentation
Designing, planning and executing tests (manual and CI)
Patch management (collaborator management)
subversion, git
compiling open source software on various operating systems
Perl package management (CPAN)
IBM XL C/C++ v10/v11 for AIX
Oracle Studio 12.1 for Solaris (Sun Studio)
GNU Compiler Collection 4.x (gcc/g++ 4.2, 4.4, 4.6, 4.7, 4.8, 4.9, 5.2, 6.0, 7.0, 8.0)
MS Visual Studio for C++ 2008, 2015
Xcode 3.3, 4.5, 5.1, 6.1, 7.3 (Clang, LLVM), 9.1, 10.1
GNU make, BSD make, GNU Autotools (autoconf, automake, libtool, ...)
Microsoft Windows Services for Unix (WSU, Interix), Windows Subsystem for Linux
Solaris 10 & Solaris 11 (OpenSolaris, Solaris Express), AIX, HP-UX, NetBSD, FreeBSD, Mac OS X, Debian (Lenny, Squeeze), SuSE Linux (SLES, SLED), Red Hat Enterprise Linux
Intel x86 (i386, i586, i686), x86_64, amd64, Sparc, PowerPC, MIPS, ARM, DEC Alpha
Monitoring sensors / operating system statistics / OS internal structures (process tables, network/interface configuration, libstatgrab, ...)
ANSI SQL
Maintaining SQL::Statement (SQLite & PostgreSQL as reference), DBD::CSV and DBD::File (DBI), DBI::Test
PostgreSQL, MySQL
Test automation, parallel tests, Test Anything Protocol
Porting open-source software to AIX, HP-UX, NetBSD, FreeBSD and Mac OS X
ASN.1 encoding / decoding, SNMP
D-Bus for responding to system events
Continuous integration
WxGTK, gtk2

Apr 2006 - Apr 2007

1 year 1 month

Software Development for NGN Components

Telecommunications, Next Generation Networks

Developing C++ software for NGN components
Porting low-level software from older ISDN hardware to current hardware
Implementing configuration (persistent & volatile) & communication between hardware layer & configuration layer including GUI via XML
Developing communication components for an xDSL board (DSLAM - DSL Access Multiplexer)
Implementing a virtual data link layer for Ethernet
Unit testing (Unix host-based)
vxWorks 5.5, Tornado 2.2
vxWorks 6.3, Wind River Workbench 2.5
Eclipse 3.2
Ethernet drivers (data link layer)
IP, TCP, UDP (TCP/IP, UDP/IP)
PPPoE, DHCP, VLAN, single & double-tagged Ethernet, Wireshark
ISDN
Customer accounting
Windows XP, FreeBSD 6
XML, XSD, SAX
STL, GNU C++ 3.4
C development, C++ development
FreeScale microcontrollers
ADSL, VDSL, SHDSL
Perl, shell scripting
Enterprise Architect
ISDN line codes & protocols
Altova XMLSpy 2005
Fedora Core 5
Java (Virtual Machine)
BNG (B-RAS)

Jan 1993 - Mar 2006

13 years 3 months

Freelance software developer & consultant

Automotive, telecommunications, banking, IT service providers, retail

Programming for Unix
Embedded development (data transmission), driver programming
Software design
Unit tests, regression tests
Quality assurance
Network administration
Software packaging & distribution
Seminar leadership, training
ANSI C (C89, C99)
C++ (C++98), STL, Boost
Perl 5, CPAN, DBI
Oracle, Toad, DB2, MySQL, PostgreSQL
Microcontrollers NEC CAN3+ (e.g. µPD780828, ...), ARM (e.g. PXA270)
GNU C/C++, IBM CSet for C/C++ (VisualAge, xlc), IAR Embedded Workbench, Watcom C/C++, ...
XML (DOM, XML-RPC, SAX, XSLT, SOAP)
Linux, Solaris, AIX, FreeBSD, OS/2, Windows 2000, Windows NT 4.0, MS-DOS
ClearCase, Subversion, CVS, RCS, MSK SI, TeamConnection
Rational Rose
Microsoft Office (incl. Visio)
DHCP, BOOTP, SMTP, UDP, TCP, FTP, SSH, ICMP, ESCON
Sockets, POSIX threads (pthreads)
Andrew Filesystem / Kerberos management
HACMP

Summary

Simplicity is the result of maturity. – Friedrich Schiller

My work does not follow a fixed plan, but adapts flexibly to an evolving project goal – always in line with the company's mission. By choosing small, deliberate steps, we create the openness needed to respond appropriately to unforeseen events and necessary adjustments. The focus is not only on technical requirements but also on business goals, stakeholder interests, and existing organizational structures.

In this iterative approach, usable intermediate results have greater value than merely or quickly reaching an originally set target. With each step, the understanding of the actual needs and framework conditions grows.

In this way, simplicity does not come from simplification, but from maturity: as the result of continuous reflection, honest communication, and the ability to distinguish the essential from the nonessential. It is the expression of a solution that not only works but endures – because it has grown through the interplay of all influencing factors.