Solution Architect — Java Platform Modernisation

Our client, a leading organization in the transport and infrastructure sector, is looking for a Senior Solution Architect for a mission-critical planning platform used for train traffic and infrastructure works. You will design, document and govern the solution architecture in line with the enterprise architecture, maintain the architecture repository in ArchiMate, and stay close enough to the code to discuss the concrete impact of decisions with the engineering teams. The landscape combines legacy and microservices: OpenShift, AIX, Oracle, Redis, Java 8 and 17-21, Angular, Swing, HashiCorp Vault, IBM MQ, Kafka and Elastic.

• Identify stakeholders and analyse and challenge functional, non-functional, regulatory and security requirements.
• Define the scope, boundaries, assumptions and dependencies of the solution.
• Build a technical inventory and architecture roadmap covering legacy maintenance, platform modernisation and cybersecurity.
• Design the target architecture and compare scenarios on benefits, cost, risk, impact and reversibility.
• Record key decisions in Architecture Decision Records.
• Run gap analyses, propose transition stages and estimate implementation costs.
• Prepare architecture reviews and perform conformity reviews during delivery and before go-live.
• Guide design, development, integration, test, security and operations teams; take part in refinement and do targeted code reviews on service boundaries, interface contracts and error handling.
• Build and maintain the architecture models in ArchiMate (e.g. Sparx EA) and enforce modelling conventions.
• Organise knowledge transfer and keep architecture documentation up to date.
• Be available for the on-call service.

• You have 10+ years of experience with enterprise and solution architecture, governance and requirements management.
• You have 10+ years of experience as a solution architect on production systems, designing and integrating solutions across multiple technical domains and stakeholders.
• You master architecture modelling and produce coherent views across business, data, application and technology.
• You reason in scenarios, trade-offs, risks, dependencies, cost and value.
• You know integration patterns, APIs, data, infrastructure, cloud and cybersecurity, and understand operability, resilience, continuity, performance and lifecycle.
• You have experience with architecture reviews, risk analyses and guiding implementations.
• You have hands-on software development experience recent enough to be credible towards an engineering team.
• Practical knowledge of TOGAF is recommended; certification and knowledge of security practices and an ITSM framework are a plus.
• You are fluent in French and/or Dutch and English, spoken and written.

• Start date: 01-12-2026
• Duration: 5 years
• Work regime: Full-time
• Location: Brussels
• Working model: Onsite (including availability for the on-call service)
• Contract: open to both permanent employees and freelancers