We extend propositional dynamic logic (PDL) with variables ranging over an innitedomain. This extension, called parametrized PDL or PPDL for short, is interpretedover parametrized transitions systems whose edges are labeled with letters or variablesand whose states are labeled with non-parametrized propositions. We show that thesatisability problem for PPDL is decidable.We apply these results to the composition problem of web services in presence of con-straints on the global ordering of the message-exchange events between the agents.We express the client specication and the available services as parametrized tran-sitions systems and we express the behavioral constraints as a PPDL formula thatthe generated orchestrator must fulll. It turns out that the model of such a formularepresents the desired orchestrator.