Deriving Abstractions from a Software Object Network

High level abstractions from programs can be obtained by extracting relational information from programs to form a software object network, and deriving high level abstractions from that network. The authors show how to obtain several interesting abstractions such as subsystems, ripple effects, logical layers and modules from a software object network represented by a C program database. These abstractions assist programmers in understanding the program structure and point out potential areas for improvement. This document then demonstrates how rule-based software restructing can be performed by accessing the relational information stored in the program database. Keywords: Computer programming; CIA(C Information Abstraction)

The derivation of performance expressions for communication protocols from timed Petri net models

Petri Net models have been extended in a variety of ways and have been used to prove the correctness and evaluate the performance of communication protocols. Several extensions have been proposed to model time. This work uses a form of Timed Petri Nets and presents a technique for symbolically deriving expressions which describe system performance. Unlike past work on performance evaluation of Petri Nets which assumes a priori knowledge of specific time delays, the technique presented here applies to a wide range of time delays so long as the delays satisfy a set of timing constraints. The technique is demonstrated using a simple communication protocol

Elasticity and Petri nets

Digital electronic systems typically use synchronous clocks and primarily assume fixed duration of their operations to simplify the design process. Time elastic systems can be constructed either by replacing the clock with communication handshakes (asynchronous version) or by augmenting the clock with a synchronous version of a handshake (synchronous version). Time elastic systems can tolerate static and dynamic changes in delays (asynchronous case) or latencies (synchronous case) of operations that can be used for modularity, ease of reuse and better power-delay trade-off. This paper describes methods for the modeling, performance analysis and optimization of elastic systems using Marked Graphs and their extensions capable of describing behavior with early evaluation. The paper uses synchronous elastic systems (aka latency-tolerant systems) for illustrating the use of Petri nets, however, most of the methods can be applied without changes (except changing the delay model associated with events of the system) to asynchronous elastic systems.Peer ReviewedPostprint (author's final draft

Using influence diagrams for software risk analysis

Proceedings of the International Conference on Tools with Artificial Intelligence128-131PCTI

An Efficient Organization or Large Frequency-Dependent Files for Binary Searcking

[[abstract]]The efficient organization of a very large file to facilitate search and retrieval operations is an important but very complex problem. This paper considers the case of a large file in which the frequency of use of its component subfiles are known. The authors develop the organization of the file so that the average number of entries to locate individual items in it by means of binary search is minimized. The algorithm iteratively partitions the file into `saturated' subfiles, and with each successive iteration the average number of entries to locate an item is reduced until no more improvement is possible. Next, they extend the method to solve the realistic problem of designing an optimal memory hierarchy to hold the file in a computer system. The sizes of various memory components and location of various items of the frequency-dependent file are determined so that the average time to locate an item (over the totality of items) in the memory hierarchy is minimized for a given total cost of the memory system. A number of examples are given to elucidate the methods. Also, the characteristics and results of a Fortran implementation of the algorithms on the CDC 6600 are described[[department]]資訊工程學

Improving I/O response times via prefetching and storage system reorganization

Proceedings - IEEE Computer Society's International Computer Software and Applications Conference143-148PSIC