† Abstract–Portals Direct I/O (" PDIO") is a special-purpose middleware infrastructure for writing data from compute processor memory on Portals-enabled compute nodes to remote agents anywhere on the WAN in realtime. The prototype implementation provided a means for aggregation of outgoing data through multiple loadbalanced routing daemons, end-to-end parallel data streams through externally connected “I/O nodes”, and a bandwidth feedback mechanism for stability and robustness. It was used by one research group, demonstrated live at several conferences, and shown to deliver bandwidths of up to 800 Mbit/sec. Although the prototype met the initial design requirements for the target application, it had some limitations due to the special-purpose nature of that design. Based on experiences with that implementation, the beta version now under development has a number of interface, functionality and performance enhancements. We present the motivations for this infrastructure and the revisions that should make it a general purpose solution for users on PSC’s Cray XT3 and other compute platforms.