Migration from a Java 6/Spring 3 base to Java 21/Spring Boot 3.5.
Context
Manpower, the world leader in temporary work, is launching a program of gradual modernization of its IS built on legacy technologies to facilitate innovation on their application park. The objective is strategic because it affects applications that are essential to Manpower's business. Hosted in their private cloud, 4 of these applications, some of these applications, some of these applications will no longer be maintained in the coming months and are exposed to security risks.
Not having skills in AI-assisted modernization, Manpower entrusts Theodo with the migration, in 9 weeks, of a first critical application (Java 6/Spring 3 to Java 21/Spring Boot 3.5). This project allows them to test the feasibility of large-scale migrations while raising standards of quality, security and testing.
Challenges
- Respect functional parity: the migration must be isofunctional, without business disruptions.
- Improving quality: improving test coverage, vulnerability treatment, readability and maintainability of the code.
- Responding to strong strategic pressure: a failure of this pilot would have compromised the trajectory of complete modernization of Manpower's IS.
Our approach
3 experts (delivery, AI and software engineer) collaborated with the Manpower teams.
What made the difference:
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Tech-enabled networks of teams
Combined use of tools: Amazon Q (specialized in Java), Copilot and Cline (recognized on test migration) allowed the Theodo and Manpower teams to iterate together, quickly, to raise quality and to reduce by 3 the estimated migration time without AI.
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Right First Time
Orchestrated multi-agent AI workflow: specialized agents managed targeted tasks aligned with the target architecture, allowing 10x faster migration while maintaining continuous improvement of quality standards (tests, security, readability) via a structured technical review framework.
“This pilot had to be flawless. The Theodo method, enhanced by AI, combined technical rigor, transparency and speed — exactly what we needed to start our modernization journey.”
