In an effort to understand the glass transition, the dynamics of a nonrando
mly frustrated spin model has been analyzed. The phenomenology of the spin
model is similar to that of a supercooled liquid undergoing the glass trans
ition. The slow dynamics can be associated with the presence of extended st
ringlike structures which demarcate regions of fast spin Rips. An entropy-v
anishing transition, with the string density as the order parameter, is rel
ated to the observed glass transition in the spin model.