Paul J. Leach

An overview of the Rialto real-time architecture

The goal of the Rialto project at Microsoft Research is to build a system architecture supporting coexisting independent real-time (and non-real-time) programs. Unlike traditional embedded-systems real-time environments, where timing and resource analysis among competing tasks can be done off-line, it is our goal to allow multiple independently authored real-time applications with varying timing and resource requirements to dynamically coexist and cooperate to share the limited physical resources available to them, as well as also coexisting with non-real-time applications.This paper gives an overview of the Rialto real-time architecture as it is implemented today and reports on some of the early results obtained. In particular, it describes the use of time constraints, activities, CPU and other resource reservation, and the system resource planner, and how they work together to achieve our goal of providing a flexible, dynamic real-time computing environment.

Modular real-time resource management in the Rialto operating system

This paper describes ongoing investigations into algorithms for modular distributed real-time resource management. These investigations are being conducted in the context of the Rialto operating system-an object-based real-time kernel and programming environment currently being developed within Microsoft Research. Some of the goals of this research include developing appropriate real-time programming abstractions to allow multiple independent real-time programs to dynamically coexist and share resources on the same hardware platforms. Use of these abstractions is intended both to allow individual applications to reason about their own resource requirements and for per-machine system resource planner applications to reason about and control resource allocations between potentially competing applications. The set of resources being managed is dynamically extensible, and may include remote resources in distributed environments. The local planner conducts resource negotiations with individual applications on behalf of the user, with the goal of maximizing the users perceived utility of the set of running applications with respect to resource allocations for those applications.

Support for User-Centric Modular Real-Time Resource Management in the Rialto Operating System

This paper describes ongoing investigations into algorithms for user-centric modular distributed real-time resource management. These investigations are being conducted in the context of the Rialto operating system — an object-based real-time kernel and programming environment currently being developed within Microsoft Research.

A Conceptual Authorization Model for Web Services

This paper describes a conceptual authorization model for Web Services. It is an adaptation of those of Taos [Lamp92] and SDSI [Lamp96] with terms changed to correspond more closely to those introduced with the WS-Security model [WS02]. In contrast to the more formal and mathematical presentation used for Taos and SDSI, this presentation is conceptual and informal, which hopefully may provide more intuition for some readers; it also might provide an outline for the class hierarchy of an object-oriented implementation. In addition, this model abstracts away from issues of distribution and network security such as authentication [Need78] and encryption (for example, by assuming that messages include the unforgeable identity of the sender and are private and tamperproof) so as to focus on authorization, but it does deal with the extensibility and composability of security services, and partial trust. It also

Position paper for a workshop on "making distributed systems work"

Apollo has implemented one generation of distributed system, and is currently working on a second. In this paper, we will briefly describe: the system we have already bullt; what we learned from it; the architectural directions that we think are important for the new system; and what we expect to learn as we implement the new architecture.