This paper presents the modeling of BPEL (timed) constructs by using a new formalism WS-TEFSM (Web Service Timed Extended Finite State Machine). A formal mapping of all BPEL constructs is proposed as well as a model that corresponds to the BPEL Web services composition. The WS-TEFSM formalism allows to deal with timing constraints, data variables, clocks and priority on transitions. To perform the transformation, we define a renaming function and an asynchronous product of all partial machine corresponding to the BPEL process sub-activities. This model is enriched by the addition of priorities on transitions, which permit to handle the termination of the BPEL process and its sub-activities, and by global variables, which are used in the management of events and faults. This transformation step is essential to ensure the test of Web services. A rigorous approach is crucial as we have to deal with complex systems that manage distribution, low-coupled nature and asynchronous behaviors.