Résumé : We investigate the use of cooperation between solvers in the scheme of constraint logic programming languages over the domain of non-linear polynomial constraints. Instead of using a general and often inefficient decision procedure we propose a new approach for handling these constraints by cooperating specialised solvers. Our approach requires the design of a client/server architecture to enable communication between the various components. The main modules are a linear solver, a non-linear solver, a constraint manager, a communication protocol component and an answer processor module. This work is motivated by the need for a declarative system for robot motion planning and geometric problem solving. We have implemented a prototype called \groak %({\bf \sf C\raisebox{.2ex}o}nstraint {\bf \sf S}ystem {\bf \sf %A}r{\bf \sf \raisebox{.2ex}c}hitecture) (\textbf{\textsf C}\raisebox{.2ex}{\textbf{\textsfo}}nstraint \textbf{\textsfS}ystem \textbf{\textsfA}r\raisebox{.2ex}{\textbf{\textsfc}}hit- ecture) to validate our approach using cooperating solvers for non-linear constraints over the real numbers. Our language is illustrated by an example that also shows the advantages of cooperation.