The workflow models have been essentially operation-centric for many years, ignoring almost completely the data aspects. Recently, a new paradigm of data-centric workflows, called business artifacts, has been introduced by Nigam and Caswell. We follow this approach and propose a model where artifacts are XML documents that evolve in time due to interactions with their environment, i.e. human users or Web services. This paper proposes the AXART system as a distributed platform for collaborative work that harnesses the power of our model. We will illustrate AXART with an example taken from the movie industry. Indeed, applying for a role in a film is a typical collaborative process that involves various participants, inside and outside the film company. The demonstration scenario considers both standard workflow process and dynamic workflow modifications, based on two extension mechanisms: workflow specialization and workflow exception. The workflows, modeled using artifacts, a...