Jens Rehsack

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

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

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

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

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

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

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

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

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

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

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

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

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

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)

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

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

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

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