Delphi Developer & Java Architect & Java Developer & Kotlin Developer

Jan ist ein Java-Programmierer mit über 15 Jahren Berufserfahrung. Unter den agilen Methoden beherrscht er JIRA und Scrum, und er ist auch Scrum Master. Derzeit leitet er ein Team von 5 Personen. Er spricht Spanisch, Polnisch und Englisch, was er täglich bei der Kommunikation mit ausländischen Kunden anwendet.

Senior Architect Developer (June 2018 – Present)

Designed and maintained scalable architectures for enterprise applications, transitioning from WebSphere Java EE 6 to Spring Boot microservices on AWS and on-premises. Implemented microservices with Spring Boot and Kotlin, developing RESTful web services for inter-service communication. Led technology migrations, moving from Struts to AngularJS, ReactJS, React Native, and Vaadin, while optimizing application performance and database queries. Managed AWS and Google Cloud deployments, led development teams, facilitated Scrum ceremonies, and collaborated with major banks and government agencies.

Senior Software Developer (December 2014 – June 2018)

Developed and maintained Java EE applications on JBoss, WildFly, WebLogic, and WebSphere, utilizing Java 8 features. Implemented microservices architecture with Spring Boot, ensuring scalability and resilience. Managed databases with Oracle 11g and PostgreSQL, developed robust web interfaces using JSF and Spring MVC, and conducted unit testing with JUnit. Engaged in project management using JIRA, implemented CI/CD processes with GIT and Jenkins, and ensured security compliance with Spring Security.

Programmer (January 2011 – December 2014)

Developed and maintained the HELIOS Orange ERP system, including its core functionalities and mobile access through a DataSnap server on Delphi. Led the development of mobile applications for iOS and Android, and used Java EE 7 with CDI, JPA (Hibernate), and JTA for database operations. Collaborated with other development teams and project managers to ensure timely delivery of project milestones. Utilized SOAP and REST for web services, and Objective-C for iOS development.

Programmer (February 2010 – December 2010)

Developed web portals and content management systems for corporate clients using PHP and MySQL. Configured Apache HTTP Server, set up virtual hosts, implemented SSL/TLS encryption, and optimized performance. Created responsive and visually appealing web pages using HTML, CSS, and JavaScript. Worked closely with clients to understand their needs and deliver customized web solutions.

Programmer (February 2006 – January 2010)

Developed in-house systems for production planning, warehouse management, CRM, and ERP using PHP and PostgreSQL. Created and maintained web applications, ensuring they were user-friendly and efficient. Utilized Java Spring MVC for backend development, and collaborated with various departments to meet system requirements. Ensured database integrity and performance with PostgreSQL.

Programmer and Businessman (October 2003 – March 2006)

Developed point-of-sale systems and e-commerce solutions for retail businesses using Delphi Borland Pascal and Java EE. Managed databases with MySQL and Oracle, ensuring efficient data storage and retrieval. Collaborated with clients to understand their business needs and provide tailored software solutions. Balanced technical development with business management to grow a successful freelance career.

Programmer (March 1998 – October 2003)

Developed software for managing telephone exchanges and VoIP solutions using Borland Pascal and Java. Managed databases with Oracle 8i and 9i, optimizing performance and ensuring data integrity. Collaborated with telecommunications engineers to design and implement reliable software systems. Maintained and updated existing systems to meet evolving technological standards.

Programmer (September 1993 – March 1996)

Developed point-of-sale systems for retail chains using Borland Pascal and Delphi, ensuring efficient and reliable transactions. Managed databases using Free Pascal for cross-platform compatibility. Worked closely with retail clients to customize POS systems to their specific needs. Ensured the systems were user-friendly and integrated seamlessly with existing infrastructure.