Projects

Please choose from among the project types, platforms, or languages listed on the left, or scroll down to see a reverse chronological list.

Introducing a managed service for traffic data retention

Company:

3M Services GmbH, Hannover, Germany

Period:

03/2017 - 10/2017

Details:

I helped with the introduction of a data retention system for telecommunication metadata as required by the German law §113a-g TKG. We offered this system as a managed service to (usually small) telecom companies. These companies were to provide regular file deliveries containing metadata about phone calls and public IP address assignments. The system platform consisted of a set of servers, a hardware security module, and an Oracle database server with encryption (TDE). The application software was provided by a vendor and had processes for loading the different file types into the database and a web front end for handling database inquiries sent by law enforcement agencies.

I was responsible for the following tasks:

• Specifying the CSV file layouts and field formats.
• Defining the file handover procedure (SFTP server, checksummed files, delivery schedule, error handling).
• Leading detailed discussions with clients and the vendor as topics came up.
• Testing the first few sets of delivered files from each client to make sure the file and field formats were correct and the contents looked consistent.
• Testing the vendor software to make sure all data get stored in the database correctly, and are retrieved correctly when executing a law enforcement inquiry.
• Revising the vendor software configuration (property files) to match our specifications.
• Reporting software bugs to the vendor, discussing possible solutions where applicable, following up, and retesting bug fix deliveries. This was of particular importance because parts of the software had been newly developed for our needs and did not have the level of quality of older, proven software.

I wrote various Perl scripts for verifying client files and for generating test files, which made it possible to achieve the necessary test coverage.

Position:

Consultant

Tools used:

Perl, SQL Plus, Word, Excel

Introducing a traffic data retention solution

Company:

Unitymedia GmbH, Cologne, Germany
Technical center in Kerpen

Period:

06/2016 - 12/2016

Details:

As the project manager, I've prepared for the introduction of a retention and inquiry solution for telecommunications traffic data according to the German law §113a-g TKG:

• Planned the entire solution, including how to connect the source systems:
  • Mediation Device
  • DHCP and authentication servers
  • Reference databases with customer and infrastructure data
• Defined the solution requirements:
  • Legal requirements
  • Operational requirements (performance, hardware redundancy, problem signalling)
  • The logic for performing inquiries on the retained traffic data and for linking them to the reference data
• Evaluated the solution vendors' quotes based on features, one-time costs, operational costs, and total cost of ownership.
• Assessed the data quality delivered by the source systems based on questions like: do key fields match with reference data; are the data unambiguous and current; is there a reliable data history for resolving past events.
• Created initiatives for achieving the necessary data quality.
• Defined needed Change Requests for internal departments and external partner companies.
• Communicated with the solution vendors as well as with the internal departments responsible for providing the source data.
• Reporting, risk control, and cost control.

Position:

Project manager

Tools used:

Word, Excel, Visio, Project, SQL Developer

Testing and bug fixing for a migrated data warehouse application

Company:

T-Systems GEI GmbH, Aachen, Germany

Period:

07/2015 - 12/2015

Details:

A sizeable data warehouse application had been migrated from Informix to Oracle. As a member of a test team, I identified and analyzed problems in the migrated application, and (since the developers who had done the migration weren't available) also fixed them: runtime errors, performance problems, and deviations from the original Informix application's behavior.

These were the skills and tools most relevant to my job: Oracle SQL, PL/SQL, familiarity with various special cases, for instance in the way Oracle handles NULL values or empty strings, how CHAR fields behave differently than VARCHAR2 ones, utilization of indexes, differences in the way exceptions are handled in Oracle versus Informix, implicit conversions between strings, dates, and numbers, dynamic SQL, and measures for avoiding deadlock situations. I also created ETL process chains with Pentaho, and used the JIRA software for tracking problems.

Position:

Quality assurance and bug fixing

Platform:

Unix

Programming languages:

SQL, Perl

Additional tools used:

JIRA, Pentaho

Data analysis, loading, and reporting (free-lance cooperation)

Company:

data2fact GmbH, Königstein, Germany

Period:

07/2014 - 06/2015

Details:

I took time off to specialize in data analysis, data loading, and reporting. These areas are essential in Business Intelligence and Big Data applications, and should help me find attractive business opportunities going forward.

Here are the new tools I've learned:

• RapidMiner, a tool for doing statistical analyses like classification, regression, and clustering. Typical use cases are predicting customer churn, estimating the probability for customers to buy particular products, assessing the sentiment of customer comments or tweets, predicting physical properties of material mixes, and much more.
• Yellowfin, a browser-based reporting front-end. Strengths are self-service reports, data governance, collaboration, discussion boards, mobile consumption of reports.
• Talend, an ETL tool (extracting, transforming, and loading of data). This is useful to collect data from various sources: databases, files, Hadoop clusters, web services (like Google Analytics, Twitter etc.), applications (like SAP, Siebel, SalesForce etc.) All these data can then be stored together in a database for reporting (e.g. with Yellowfin) and analysis (e.g. with RapidMiner).

Position:

Data Analyst

Platform:

Unix

Programming languages:

SQL, Java

Additional tools used:

RapidMiner, Yellowfin, Talend

Quality Assurance for a mobile telecom Data Warehouse

Company:

T-Mobile Deutschland GmbH, Bonn, Germany

Period:

11/2008 - 06/2014

Details:

As a member of the Data Warehouse Quality Assurance team, I planned and performed acceptance tests for software changes in processing job chains.

For documenting my test cases and test runs and for tracking the errors I identified, I used the tool HP Quality Center (language: English).

Test case design was based on documents like functional specifications and code designs.

Doing my own investigations in the source code (PL/SQL and Unix shell scripts) and keeping in touch with the developers were no less important, though.

The Data Warehouse was implemented on Unix (Solaris) and Oracle 10 as a collection of nested process networks, each network consisting of a set of processses and often other networks along with their dependencies and synchronization rules.

These process networks were maintained and executed within a tool named UC4.

Usually when running my tests, though, I used manual Unix commands or (for overnight jobs) custom shell scripts.

That way I could skip processes not relevant to my test, and adapt process parameters, e.g. to change the time period to be processed, or to change parallelism.

I managed to make working with complex nested process plans much easier for my colleagues and myself by implementing a tool in Perl that reads process plans exported from UC4 in XML format, analyzes their dependencies, automatically identifies sequential and parallel process groups, and outputs a nested outline with proper indentation.

In addition, I took part in document reviews.

Position:

Quality assurance

Platform:

Unix

Programming languages:

SQL, Perl, VBA

Additional tools used:

HP Quality Center

Application support for Order Intake, Billing, and Customer Care

Company:

TELE2 Billing GmbH, Düsseldorf, Germany

Period:

04/2005 - 06/2008

Details:

As a consultant, I provided application support for the family of Web-based software applications that were being used by different regional branch call centers for entering their growing volumes of orders (wireline preselection, mobile phones, ADSL, VoIP) and that also performed the necessary provisioning with third parties (wireline operator, fulfillment companies, print shops, credit checking agencies, Element Manager, SIP proxy).

I worked on my own first, and later as part of a team.

My main tasks were:

• Creating and maintaining a perl program that permanently tests the call center web sites for availability and automatically sends notifications by mail and SMS. This allowed us to quickly react to problems.
• Creating Perl report scripts that read new orders from the Oracle database and mail them to the regional branches for information purposes.
• Devising work processes and tools (in Perl and Visual Basic) for myself and my team mates.
• Preliminary analysis of software, database, and network problems; communication with the software supplier, database administrators, and network maintenance staff.
• Acceptance testing and installation.
• Handling trouble tickets.

After one and a half years in intake application support, I moved to the neighboring team, now supporting the billing & customer care system, building upon the base of tools and methods that I had developed by then.

As the software supplier for this system had comparably slow, expensive development cycles, I implemented scripts and procedures to provide added functionality and bug work-arounds, using direct database read access and performing safe customer updates through loader executables.

Here, my main tasks were:

• Creating work-around scripts that correct wrong/missing data items in files either generated by or loaded into the system.
• Creating add-on scripts that use a combination of attributes like priceplan, phone type, and service options to add certain recurring fees to customers.
• Implementing monitoring mechanisms that detect high-debt customers and take automated steps to control the credit risk, like changing the customers' category attributes, disabling their phone service, or adding them to an action list so the customer care agents can check or contact them.
• Analyzing and cleaning data inconsistencies using direct SQL access.

Position:

Application support

Platform:

Windows XP, Linux

Programming languages:

Perl, SQL, Visual Basic

Additional tools used:

Word, Excel, ARS Remedy

Software development for mobile phone Billing & Customer Care

Company:

T-Systems, Aachen, Germany (formerly debis Systemhaus GEI mbH)

Period:

08/2004 - 03/2005

Details:

As a member of a developer team, I implemented change requests and fixed bugs for the mobile phone Billing & Customer Care system "Jupiter" using C, GemBase, and DCL on DEC Alpha under VMS.

(I had worked for this company before, see below)

Position:

Software developer

Platform:

Dec Alpha under VMS

Programming languages:

C and GemBase DML

Additional tools used:

CMS (Code Management System), MMS (Make Management System), Perl

Billing consulting: Reports, automation, mass updates and fixes

Company:

debitel, Stuttgart

Period:

01/2004 - 04/2004 (I got a letter of recommendation)

Details:

Aa a Perl and GemBase programmer and Jupiter Billing & Customer Care expert, I created reports for analyzing various data problems, implemented a daily batch job that computes and creates credits for a product promotion, and converted several Jupiter-to-Data Warehouse data export jobs from DML to Perl.

Position:

IT consultant and developer

Platform:

Dec Alpha under VMS; Unix

Programming languages:

Perl and GemBase DML

Additional tools used:

Lotus Notes

Software development for mobile phone Billing & Customer Care

Company:

T-Systems, Aachen, Germany (formerly debis Systemhaus GEI mbH)

Period:

08/2003 - 12/2003

Details:

As a member of a developer team, I implemented change requests and fixed bugs for the mobile phone Billing & Customer Care system "Jupiter" using C, GemBase, and DCL on DEC Alpha under VMS.

(I had worked for this company before, see below)

Position:

Software developer

Platform:

Dec Alpha under VMS

Programming languages:

C and GemBase DML

Additional tools used:

CMS (Code Management System), MMS (Make Management System), Perl

Introducing, testing, and operating a new Amdocs billing software installation

Company:

Vodafone D2 GmbH, Düsseldorf, Germany

Period:

01/2001 - 04/2003 (I got a letter of recommendation)

Details:

As a consultant (team member) I helped with introducing, testing, and operating a completely new Amdocs software installation for billing millions of mobile phone customers.

Using a combination of Excel, Word, Visual Basic, and Unix Shell, Perl, and SQL, I created a system that greatly simplifies, streamlines, and semi-automates the numerous manual activities that my team colleagues have to carry out during each and every bill run.

That system also contains the accumulated procedural knowledge of the billing team, which is subject to frequent updates due to on-going process improvements and regular deployment of new software releases.

My work is of great help when training new colleagues and implementing changes in the billing process.

It also contributes significantly to improving the operating safety as well as accelerating the process runtime.

Before my consulting contract ended, I had the opportunity to give a detailed presentation before auditors, giving them an insight into our billing process and our methods of assuring quality and safety. Again, my system helped me leave an excellent impression.

Position:

IT consultant, software tester, operator

Platform:

Enterprise/Unix, Windows PCs

Programming languages:

Unix Shell, Perl, PL/SQL, Visual Basic (VBA)

Additional tools used:

Excel, Word, Visio

Software development for mobile phone Billing & Customer Care

Company:

debis Systemhaus GEI mbH, Aachen, Germany

Period:

10/1998 - 12/2000

Details:

As a member of a developer team, I developed change requests for the mobile phone Billing & Customer Care system "Jupiter" using C, GemBase, and DCL on DEC Alpha under VMS.

Position:

Software developer

Platform:

Dec Alpha under VMS

Programming languages:

C and GemBase DML

Additional tools used:

CMS (Code Management System), MMS (Make Management System)

Software for generating 3D window models for architects ("ArchiGlazing")

Company:

Graphisoft R & D Rt., Budapest, Hungary

Period:

05/1999 - 05/2002 (besides other activities)

Details:

In a collaboration with Jürgen Siebert from Dimension GmbH, Iserlohn, Germany, I fully developed the GUI application "ArchiGlazing" for creating 3D models of windows for use with the leading architectural CAD application "ArchiCAD" from Graphisoft.

While Jürgen provided the requirements specification, the artwork, and the German user manual, I was responsible for the entire development.

The application offers several window types, including vertical or slanted glass constructions based on free-form footlines, and window frames with a free-form outline and arbitrary window bars.

Graphisoft sells our application world-wide as a standard add-on for use with their product, ArchiCAD, and took over further development after we delivered the first two releases.

I developed the application on Apple Macintosh and Windows computers using C++.

Like with my former development, "StairMaker", an intimate knowledge of math and geometry was required to implement the code for generating the window models.

Position:

Implementation in C++: Gert Rieger. User interface design, graphical artwork, and user manual: Jürgen Siebert.

Platform:

Windows and Macintosh.

Programming languages:

On Windows: MS VC++ (Microsoft Corp). On Macintosh: CodeWarrior C++ (MetroWerks Inc).

Controlling software for industrial pressing machines

Company:

test GmbH und Co KG, Bielefeld, Germany

Period:

03/1992 - 12/1993 and 07/1997 - 08/1998

Details:

I developed the complete software for two subsequent generations of controller boards for industrial pressing machines.

The former generation was a custom design by an electronics company and required me to implement the entire controlling software for the CRT screen, key pad, serial communications line, and MemoryCard interface.

The latter generation was based on a standard industry PC board ("MOPS") running under MS-DOS.

Position:

Software developer

Platform:

The controller software was developed on Windows.
Auxiliary programs for converting the machine feature descriptions and the screen font were developed on Macintosh.
Target system: (a) Custom-designed processor board, (b) industry-standard PC board (MOPS).

Programming languages:

C; assembly language for the 80186 processor and 80154 microcontroller.

3D models for architectural CAD

Company:

Various architectural bureaus

Period:

01/1988 - 08/1998 (besides other activities)

Details:

I created various 3D models of windows, doors, dormer windows, steel construction elements and others for use with the leading architectural CAD application "ArchiCAD" from Graphisoft.

The models were implemented using ArchiCAD's built-in graphic description laguage GDL. They adapt flexibly to different parameter settings and can be used on Windows and Apple Macintosh computers.

Also, I created documentation using Microsoft Word and Adobe Illustrator.

I sold the models directly to architectural bureaus.

Position:

Software developer

Platform:

Creation on Apple Macintosh under System 7 and Mac OS 8.
Target systems: Macintosh and Windows.

Programming languages:

GDL (graphic description language).

Company presentation on a multimedia CD ROM ("EDELHOFF-CD")

Company:

Edelhoff AG, Iserlohn, Germany

Period:

01/1997 - 07/1998

Details:

In a collaboration with Jürgen Siebert from Dimension GmbH, Iserlohn, Germany, I created an interactive, multimedia company presentation for the Edelhoff AG, an Iserlohn waste disposal company.

While Jürgen created the overall look, design, and still graphics material, I was responsible for doing the application programming in MacroMedia Director using its built-in Lingo programming language, digitizing the video material provided by Edelhoff with Adobe Premiere and Apple QuickTime, and putting the finished application on the CD ROM master used for pressing several thousand copies.

The presentation can be viewed on Windows and Apple Macintosh computers.

Position:

Creating the presentation in MacroMedia Director complete with programming in Lingo; digitizing the customer's video tapes with a Targa video card and compressing the movies for CD ROM: Gert Rieger.
Creating the overall presentation design and button artwork, preparing the still graphics, video editing in Adobe Premiere: Jürgen Siebert.

Platform:

Creation on Macintosh.
Target systems: Macintosh and Windows.

Content creation system:

MacroMedia Director™ with the Lingo programming language.

Additional tools used:

Illustrator™, Photoshop™, Premiere™ (Adobe Systems Inc.)
Media Cleaner Pro™ (Terran Interactive)

Picture catalog on CD-ROM ("Löwe CD")

Company:

Fox LightWare GmbH, Bielefeld, Germany
Client: löwe team GmbH, Düsseldorf, Germany

Period:

09/1996 - 10/1997

Details:

Like project "Bavaria CD" 05/1995 - 09/1995 (see below).

Added features:

The full resolution pictures are stored in an encrypted format.

Selected pictures are instantly made available when the customer enters a code number they can obtain from the picture agency for a charge.

I developed the application on an Apple Macintosh computer using the CodeWarrior integrated development environment with C++ and Embedded SQL (dtf).

Position:

Software developer

Platform:

Macintosh

Programming languages:

C++, embedded SQL (dtF)

Software for generating 3D stair models for architects ("StairMaker")

Company:

Graphisoft R & D Rt., Budapest, Hungary

Period:

10/1995 - 02/1997 (besides other activities)

Details:

I fully developed a GUI application for creating 3D models of staircases for use with the leading architectural CAD application "ArchiCAD" from Graphisoft.

The application ("StairMaker") offers a range of different stair types and shapes as well as railing types.

The stair's top-down view is displayed and updated while the user enters its various dimensions and measurements numerically.

I also created the German user manual in PageMaker, complete with figures and illustrations, using the layout guidelines provided by Graphisoft.

Graphisoft sells "StairMaker" world-wide as a standard add-on for use with their product, ArchiCAD.

After I had developed three major versions of "StairMaker", I handed the source code over to Graphisoft, and they have been developing subsequent versions since.

I developed the application on Apple Macintosh using Object Pascal with the MacApp framework first, later with the Think Class Library.

Still later I continued on Windows using Microsoft Visual C++ with the Microsoft Foundation Classes (MFC).

An intimate knowledge of math and geometry was required to implement the code for generating the stair models.

Position:

Designing the user interface and functional features, implementation in Object Pascal and C++, creating the user manual.

Platform:

Macintosh and Windows.

Programming languages:

StairMaker release 1 and 2: Object Pascal with the MacApp framework and the Think Class Library.
Release 3: MS VC++ with the Microsoft Foundation Classes.

Additional tools used:

User manual in PageMaker™ (then Aldus Corp.),
graphical artwork for both the user interface and the manual in PowerDraw™ (Engineered Software)

Porting a company catalog on CD ROM ("Who supplies what? CD-Marketing")

Company:

Fox LightWare GmbH, Bielefeld, Germany
Client: Wer liefert was? GmbH, Hamburg, Germany

Period:

08/1994 - 01/1997 (besides other activities)

Details:

I ported a complex CD ROM retrieval application, implemented in the C language, from Windows to the Apple Macintosh.

I did that work for the five subsequent CD ROM releases 1/95 to 1/97.

The application has a graphical user interface (GUI) in six languages, with screens that automatically adapt to different monitor sizes.

Position:

Software developer

Platform:

Macintosh

Programming languages:

C

Picture catalog on CD ROM ("Bavaria CD")

Company:

Fox LightWare GmbH, Bielefeld, Germany
Client: Bavaria AG, Gauting, Germany

Period:

05/1995 - 09/1995

Details:

I fully developed a GUI application designed for a picture agency to distribute a comprehensive catalog with samples of their pictures on CD ROM, allowing the customer to select and order pictures.

The pictures are stored in JPEG format, and I used a small "dtf" database to store information about each picture. The user can search for key words, page through the picture samples, mark desired pictures, and print or fax an order.

The application plays background music, can be switched between several languages at any time, and the graphical user interface adapts seamlessly to screen sizes ranging from 13" to 21".

I developed the application on an Apple Macintosh computer using the CodeWarrior integrated development environment with C++ and Embedded SQL (dtf).

Position:

Software developer

Platform:

Apple Macintosh under System 7

Programming languages:

C++, embedded SQL (dtF)