Luis Felipe Cabrera

Herald: achieving a global event notification service

This paper presents the design philosophy and initial design decisions of Herald: a highly scalable global event notification system that is being designed and built at Microsoft Research. Herald is a distributed system designed to transparently scale in all respects, including numbers of subscribers and publishers, numbers of event subscription points, and event delivery rates. Event delivery can occur within a single machine, within a local network or Intranet, and throughout the Internet. Herald tries to take into account the lessons learned from the successes of both the Internet and the Web. Most notably, Herald is being designed, like the Internet, to operate correctly in the presence of numerous broken and disconnected components. The Herald service will be constructed as a set of protocols governing a federation of machines within cooperating but mutually suspicious domains of trust. Like the Web, Herald will try to avoid, to the extent possible, the maintenance of globally consistent state and will make failures part of the client-visible interface.

Advances in Windows NT storage management

Windows NT 5.0 introduces fundamental changes to storage management. The new infrastructure in NT 5.0 can adapt to future changes in storage devices and media, brings a more powerful set of management mechanisms, and supports more base services within the system. Most of the changes are transparent to legacy applications and to users, but software producers who want to deploy advanced functionality should realize increased benefits from the underlying infrastructure. Windows NT now supports the dynamic plug-and-play of storage devices and the growth and mounting of storage volumes. It also frees the NT system from drive letter limitations and incorporates several new file system features to aid the development of enterprise-class storage management solutions. The article describes two new mechanisms present in Windows NT 5.0, the reliable change journal and the reparse points. It also presents storage management infrastructure subsystems and services that help administer storage. Both mechanisms are designed to facilitate the robust and efficient administration of an increasing volume of data whose lifetime grows over time.