Freelance software developer              
Freelance software development           
C++, Java (J2SE,J2ME,J2EE,JSP), Perl and PHP
Linux, MacOS, MacOSX and Windows       

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Java-Projects

Most of the following projects where implemented on a contract basis.


ASP Java (J2EE/J2ME/J2SE) Perl PHP Administration



V-CARD

CurriculumVitae
Stefan Sonntag
Computer Scientist
(Freelance software developer)
Sonntagstr. 27
10245 Berlin
Germany
E-Mail stefan@stefan-sonntag.com
Description Language Link
Design and Implementation a Client/Server system to execute electronic payment transactions with different payment methods ( e.g. CreditCards ). Specials:
  • SSL-encrypted communictation between client and server
  • Different payment methods are implemented as plugins
  • Integrating the server in existing payment infrastructure
  • Transactionfiles exported from legacy systems can be convereted customer specific to an internal format to execute the transactions in a batch process. The results can be downloaded by the client
Java/Swing Application
Design und implementation of the multiuser server SUSHI to easily create multiuser applications using FlashMX, Flash Lite and Java (J2SE/J2ME). Java SUSHI Multiuser Server
Implementation of an ecard system.

A web interface allows an administrator to maintain the ecard motifs and categories.

The ecard can be created using two methods:

1.) The ecard is saved a configurable time on the webserver in the form of a html page and the corresponding link is sent to the receiver

2.) An image is dynamically created using the Java2D-API containing the motif and the text and is attached to the email
JSP http://www.wiley-vch.de/publish/dt/entertainment/cards
Porting an intranet news system from PHP to JSP for BASF-Pharma PHP/JSP Intranet
Implementation of a fault tolerant search to find services offered by TÜV-Hessen.

After selecting the desired service the closest center to the users home is selected through a geographic search that uses longitude and latitude information.

The Employees of TÜV-Hessen can administrate the services by uploading an excel sheet or via a web interface.
JSP/Perl http://www.tuevhessen.de
Porting various credit calculators from C++ to Java Servlets for Hypotheken Discount and the direct bank of Volkswagen.

Dynamically generated view of the actual interests.

Hypotheken Discount replaced the Java Servlets by a Net.Data solution.
Java Servlets http://www.vw-bankdirect.de/cgi-bin/vwbankdirect/index.pl?Finanzieren&Hypo&Rechner
Porting a Delphi application to prove the creditworthiness of an applicant for credit to Java Servlets for Hypotheken Discount.

The calculator has been replaced by a Net.Data solution.
Java Servlets Deprecated
Improvement of an existing web based system for entering and evaluating working time.

Employees can enter the time they worked on active projects. The projects are assigned to customers.

With an administration module privileged users can evaluate the project-, customer- and employee specific working time and manage the customers, projects, employees and privileges.

The administration module is protected and is only accessible by employees with the corresponding privileges. The privilege system is based on groups and users being assigned to them. Privileges like adding or deleting a customer or evaluation of projects can be granted to groups and revoked from them.

Employees can see their working time as daily, weekly, monthly or yearly views
Java Servlets Intranet


 

   
StefanSonntag C++, Java, Perl, PHP-native speaker