The evolution of the World Wide Web from hypermedia information repositories to hypermedia distributed applications and services oriented architectures (SOA) has introduced new features in the current and incoming web. An important feature is the dynamism of its contents and services, which induces the dynamism of the client behavior. This feature represents a major constrain when modeling and generating current web workload. In this paper, we first review the state of the art for web workload generation, focusing on the approach based on workload models. After that, we analyze a representative subset of the state of the art workload generators that use workload models, concentrating on those model characteristics that represent dynamism in the workload generation. The study reveals that five generators present some capabilities to reproduce this dynamism, but only the GUERNICA approach improves the dynamic workload generation by using users' behavior models. Finally, we discuss GUERNICA and describe how it generates dynamic workload by addressing both user behavior and workload distribution.