June 1, 2024

Context

THESEE is the national platform used by French security forces to process online scam and fraud reports — a critical business application operating in a regulated, security-sensitive context. The system is built on a multi-technology stack (Java, PHP, Python), reflecting layers added over time as functional needs evolved.

Constraints

• Handling of sensitive data tied to law-enforcement and fraud-reporting activity, under strict security requirements.
• A multi-technology codebase (Java, PHP, Python) to maintain and evolve coherently, without introducing regressions across module boundaries.
• Stability and reliability requirements typical of a nationally used platform, where changes must be qualified before release.
• Continuous functional evolution driven by changing technical and regulatory requirements, requiring maintenance to be both corrective and adaptive rather than one-off.
• Long-term maintainability, given the platform's expected lifespan and the number of contributors touching it over time.

Contribution

• Performed corrective and adaptive maintenance across the Java, PHP, and Python components of the platform.
• Analyzed reported issues and existing code to identify root causes before implementing fixes, rather than treating symptoms.
• Improved existing code where maintainability or clarity issues were identified during maintenance work.
• Took part in the application qualification process, verifying that changes met functional and technical requirements prior to deployment.
• Conducted technical audits, supported deployments, and produced documentation to keep the platform's technical state traceable and understandable for other contributors.

Approach

Work followed a maintenance-driven approach rather than a greenfield build: changes were scoped and qualified individually to limit risk on a platform already in production use. Adaptive maintenance was used to keep the system aligned with evolving technical and regulatory requirements, while corrective maintenance addressed defects as they surfaced. Given the multi-technology environment, care was taken to understand each component's boundaries and conventions (Java, PHP, Python) before making changes, to avoid inconsistencies between modules maintained by different teams over time. Technical audits and a qualification step before deployment provided a check against regressions in a security-sensitive context. Documentation was treated as part of the deliverable, not an afterthought, to keep the platform maintainable as contributors and requirements change.

Outcome

• The platform stayed aligned with evolving technical and regulatory requirements through ongoing adaptive maintenance.
• Issues identified during maintenance and audits were addressed through targeted, qualified changes, limiting risk of regression on a production system.
• Documentation and audit work improved traceability of the platform's technical state for other contributors.
• Working across Java, PHP, and Python components helped preserve consistency in a codebase built on multiple technologies.

Stack: Java, PHP, Python.