  We review recent developments in the field of microscopic transport model
calculations for ultrarelativistic heavy ion collisions. In particular, we
focus on the strangeness production, for example, the phi-meson and its role as
a messenger of the early phase of the system evolution. Moreover, we discuss
the important effects of the (soft) field properties on the multiparticle
system. We outline some current problems of the models as well as possible
solutions to them.
