This paper studies the problem of checking the simulation preorder for data-centric services. It focuses more specifically on the underlying decidability and complexity issues in the framework of the Colombo model . We show that the simulation test is
-complete for Colombo services without any access to the database (noted
-complete when only bounded databases are considered (the obtained model is noted
). This is a decidability border since we have shown in previous work that the simulation test for unbounded Colombo is undecidable. Moreover, as a side effect of this work, we establish a correspondance between
, restricted to equality, and Guarded Variable Automata (GVA) . As a consequence, we derive EXPTIME-completeness of simulation for GVA.