A public-sector organisation in the Belgian social security sector is updating its application landscape, including Java applications that support long-running administrative processes in Brussels, Belgium. This junior Java Developer role focuses on migrating GlassFish applications to Payara 5 while maintaining services built with Java 8, Spring Boot 2.7.x, Spring 5.3.x, Hibernate 5.5.x and GWT 2.7. The work forms part of public-service application modernisation in the Brussels-Capital Region, with data held in DB2 and PostgreSQL.
The mission
The project covers an established application landscape rather than a greenfield build. Applications currently run on GlassFish 2, GlassFish 3 and GlassFish 4, and must be adapted and validated for Payara 5. The persistence layer uses DB2 and PostgreSQL relational databases, while Gradle 5.x manages the builds. The work matters because these applications support administrative services within the Belgian social security system and must continue to operate as the runtime platform evolves.
As a junior Java Developer, you will take responsibility for defined adaptations within the existing codebase and connect them to the wider migration plan. Your day-to-day work will include reviewing application behaviour, updating Java and Spring components, checking Hibernate mappings, and addressing compatibility issues between GlassFish and Payara. You will also work with GWT 2.7 interfaces and with both DB2 and PostgreSQL when changes affect data access. The expected experience level is junior, with approximately three years of professional development experience and the ability to work independently on assigned changes.
Your responsibilities
- Adapt application components running on GlassFish 2, 3 and 4 so they can operate on Payara 5 without loss of required functionality.
- Implement and maintain Java 8 changes across Spring 5.3.x and Spring Boot 2.7.x services.
- Review and update Hibernate 5.5.x persistence logic across DB2 and PostgreSQL relational databases.
- Maintain Gradle 5.x build configurations and resolve dependencies or runtime compatibility issues arising during migration.
- Analyse GWT 2.7 screens and application flows, then validate changes with the relevant technical and functional checks.
- Document migration-related changes and coordinate with colleagues when issues cross application, database or runtime boundaries.
Your profile
Essential skills
- Bring approximately three years of professional software development experience, with a junior-level profile.
- Work confidently with Java 8 and understand the implications of moving toward Java 11.
- Develop applications with Spring Boot 2.7.x and Spring 5.3.x.
- Use Hibernate 5.5.x and GWT 2.7 within an existing application landscape.
- Maintain Gradle 5.x build configurations and investigate build or dependency issues.
- Work effectively with DB2 and PostgreSQL relational database systems.
- Analyse legacy application behaviour, isolate compatibility issues and communicate clear implementation findings to colleagues.