The data needs of current and future PetaScale applications have increased over the last half decade to the extent that appropriate data management has become a crucial requirement. This concerns not only the storage of data produced by the new class of PetaScale applications, but also the data exchanges needed for coupling applications with concurrent analysis, online data visualization for validation, and others. To address such dynamic code coupling, we introduce the concept of an extensible, dynamic, and flexible data workspace, termed LIVE. In contrast to the data exchanges programmed with MPI, MPI-IO, or grid software, LIVE focuses on data exchanges carried out without a priori knowledge of potential data requirements. Examples include exchanges required by ad-hoc or dynamically determined methods for data validation, for general data analysis tasks, or for data visualization. Run on an execution environment comprised of integrated dynamic discovery and on-line management services, LIVE is used to create a dasiadata workspacepsila for a working molecular dynamics code base utilized by mechanical and materials engineers at Georgia Tech, for multi-scale materials modeling. Measurements of both this applicationpsilas data workspace and of the basic primitives in the LIVE framework demonstrate that the environmentpsilas substantial flexibility has minimal impact on overall performance, and in fact, that it improves performance in a number of usage scenarios. In particular, for a visualization pipeline example derived from our collaborators, we see a slight improvement over a solution based on MPI-IO, and a further improvement of up to 5% by utilizing LIVEpsilas ability to overlap communication with user-specified computation.