OPPBTP - Redesign of a Critical Business Software Suite for Risk Prevention in the Construction Industry

The French Professional Organization for Prevention in Building and Public Works (OPPBTP) is responsible for raising awareness among industry stakeholders in order to prevent workplace accidents and occupational illnesses and improve working conditions. To fulfill this mission, the organization provides a web platform delivering personalized content and a range of connected SaaS services dedicated to construction companies.

Between 2012 and 2020, the successive addition of around ten tools within a monolithic eZ Publish architecture generated critical technical debt and significant performance issues. Outdated software versions and the system's growing complexity gradually blocked its ability to evolve, just as web usage patterns were undergoing profound changes.

In this context, Codéin was commissioned to define and lead a global migration strategy : transform this massive system into a suite of independent services, restore the autonomy of each business tool, and modernize the user experience. The chosen approach — progressive, batch-based, and without a tunnel effect — was designed to ensure service continuity and the long-term sustainability of the solution.

Given the platform's functional complexity and the heterogeneous nature of its components, the selected architecture is based on a division into independent services : each business tool becomes an autonomous, specialized unit that communicates with the others through REST APIs. The approach was not a like-for-like technical migration, but a complete redesign of each tool in order to rebuild on solid foundations and meet current usability and business requirements.

The separation of software layers lies at the heart of this architecture. On the front end, each application is developed in React as a Single Page Application. On the back end, business logic and data access are handled by Symfony and API Platform. This clear separation between the interface and the business engine provides immediate reusability : the exposed APIs can power mobile applications, partner portals, or any other channel without rewriting the application core.

A critical challenge in the progressive migration was authentication management. To minimize disruptions to the user experience while the legacy platform and new services coexisted, an SSO (Single Sign-On) solution was deployed in advance. Bridges were implemented to ensure session continuity between environments, although the transition period required some adjustments for users. This mechanism was a key prerequisite for making the progressive migration viable in production.

The migration strategy was validated through an initial concrete case : the redesign of the risk assessment tool (EVR). This service lies at the heart of OPPBTP's offering, enabling companies to meet their regulatory obligations by preparing their Single Occupational Risk Assessment Document (DUERP).

Its selection as the first application to be migrated was deliberate : an urgent need for modernization, a low level of dependency on other services, and a high stability requirement due to its central role in the platform's day-to-day use.

The most demanding workstream was the migration of business data : millions of records from the historical single database had to be redistributed into a redesigned and optimized EVR database. Codéin structured this process into four phases : data definition and qualification, raw extraction, validation and loading, followed by migration verification to ensure service continuity and data integrity throughout the transition.

The success of this first migration validated the target architecture and enabled the process to be industrialized for subsequent workstreams. A shared design system was implemented in parallel to ensure a consistent user experience across all migrated tools, regardless of their redesign schedule.

OPPBTP's progressive migration has delivered measurable results in terms of both adoption and the platform's technical robustness. The software suite now supports 60,000 user companies, with a sustained rate of 1,000 new registrations per month.

For the EVR tool alone, the figures demonstrate the platform's intensive use :

• Risk assessments recorded : 70,000
• Prevention actions created : 500,000+
• Entries in the business / risk reference database : 2 million+
• Database records : 100 million+

The solution is accessible on all devices : desktop, tablet, and mobile.