papers virtual time acm transactions von david jefferson (1 Ergebnisse)

Soft cover. Zustand: Very Good. David R. Jefferson, 2 papers: (1) "Virtual Time" and (2) "Virtual Time II" in "ACM Transactions on Programming Languages and Systems" and "Proceedings of the 9th Annual ACM Symposium on Principles of Distributed Computing". (1) "Virtual Time" appears in ACM Transactions on Programming Languages and Systems" July 1985 vol 3 number 3, pp 404-425 in the issue of pp 359-506. (2) "Proceedings of the 9th Annual ACM Symposium on Principles of Distributed Computing" pp 75-90 in the issue of pp 1-409. Bound in plasticized boards. Ex-library copy with a number of stamps and annotations on the front and rear endpapers and pastedowns, though no external marks. Text clean and fresh. VG copy. [++] I was surprised to find #1 so approachable and inviting! [++] Abstract: "Virtual time is a new paradigm for organizing and synchronizing distributed systems which can be applied to such problems as distributed discrete event simulation and distributed database concurrency control. Virtual time provides a flexible abstraction of real time in much the same way that virtual memory provides an abstraction of real memory. It is implemented using the Time Warp mechanism, a synchronization protocol distinguished by its reliance on lookahead-rollback, and by its implementation of rollback via antimessages." And, from the introduction: "In this paper we propose a new paradigm for distributed computation, called virtual time, and an implementation for it, called the Time Warp mechanism. The virtual time paradigm is a method of organizing distributed systems by imposing on them a temporal coordinate system more computationally meaningful than real time, and defining all user-visible notions of synchronization and timing in terms of it. The Time Warp mechanism implements virtual time, and does so in a manner that is strongly analogous to the way that paging or segmentation mechanisms implement virtual memory. Thus, the well-developed theory and terminology of virtual memory acts as a guide to understanding virtual time. Two major applications for virtual time are as a synchronization mechanism for distributed simulation and as a concurrency control mechanism for databases." 200mp.