553852
Creating a distributed environment using object oriented technology
The paper gives a detailed description of the development of a distributed environment. A brief description of an object oriented technology used in the development of the environment is also presented. The environment described is suitable for rapid prototyping of distributed applications and complete development of distributed software systems. This environment was used in the development of client/server applications and the simulation of a cellular system. The cellular system featured Call-Handoff Cell-spitting and the dynamic allocation of cellular phones in the system.
30575380
Modeling a real-time multitasking system in a timed PQ net
A system is described that integrates timed Petri nets and queueing networks to model complex, real-time systems. It includes a graphical modeling tool, called TPQN, a textual specification language, called TPQL, and a simulator, called TPQS. TPQN's capabilities are illustrated by a performance analysis of a real-time, multitasking scheduler that had been previously implemented on top of SunOS on a Sun-3 workstation. A simulation package has been developed for TPQN that allows the behavior of various complicated systems under a designated queueing network topology to be studied before the system is implemented.<<ETX>>
9167410
Computing curricula 2001 how will it work for you?
In the fall of 1998, the ACM Education Board and the Educational Activities Board of the IEEE Computer Society appointed representatives to a joint task force to prepare Computing Curricula 2001 (CC2001), the next installment in a series of reports on the undergraduate computer science curriculum that began in 1968 and was then updated in 1978 and 1991. Interim reports on the initial planning of the curriculum were presented at the SIGCSE symposium and the IEEE Frontiers in Education Conference in both 1999 and 2000. The CC2001 Task Force released its first draft report at the 2000 SIGCSE conference and plans to release its penultimate draft at SIGCSE 2001. The purpose of this session is to describe how we expect the recommendations of the report to apply in practice. The panelists represent a range of institutions and can therefore speak to the questions that audience members from similar institutions might have.
9710130
A specification language for real-time distributed systems
The authors introduce a design specification method, extended modified Petri nets (EMPN), and its description language (EMPNDL). The specification is based on a stochastic Petri-net model and is suitable for modeling real-time distributed systems. The syntax of the language is formally described in BNF grammar while the semantics is based on that for stochastic Petric nets. In addition to the modeling capability of EMPN and EMPNDL, methods for verification and validation of such systems are also discussed. EMPN and EMPNDL have been extensively used to the specification of a prototype switching system, UICPBX. Based on the presented formulation, verification and validation of UICPBX can be automated to a great extent.<<ETX>>
35042753
A Binary Single-Key-Lock System for Access Control
A binary coding method was invented and has been applied to the single-key-lock (SKL) system which achieves access control by associating with each accesser only one key and with each resource only one lock. The new system is called the binary single-key-lock (BSKL) system. In both the SKL and BSKL systems, through operations on the single-key-lock pair, the control information can be revealed. On the basis of the new binary coding method, and because binary operations are much faster, better performance for such an access control system can be achieved. The increased extensibility of the modification is also discussed. >
2457108
An object-oriented real-time distributed simulation of cellular phone switching system
The cellular phone network is a distributed system which is composed of three kinds of subsystems, a mobile phone unit, a base site station and a MSC (mobile switching center). A class of cellular phone switching systems, was chosen as the system to be studied. SUN workstations and the UNIX operating system with X windows have been employed as the core of the development environment. The object-oriented (OO) paradigm and C++ were chosen to develop the simulation. UICCELL was developed as an object-oriented system for cellular phone switching real-time multitasking simulation. UICCELL has been fully implemented and is currently running on an Ethernet LAN. A central monitor is created on the screen to manipulate and monitor the simulator. The graphical user interface displays the configuration of UICCELL and the status of processors, channels, etc. The current implementation contains 60 classes and about 20,000 lines of C++ code.<<ETX>>
8941164
Supporting agent-based distributed software development through modeling and simulation
In today's software engineering environment, it is becoming increasingly commonplace for team members and stakeholders to be distributed in multiple locations and time zones. Under these circumstances, the coordination of software development activities becomes increasingly more complex. One solution uses mobile agent-based tools to support collaborative software engineering tasks, such as requirements management. Despite the fact that development and validation of such tools would be facilitated by the use of modeling and simulation, very little work relating formal methods to agent-based system development has been performed. This paper therefore presents a hierarchical colored Petri Net (CPN) model as a formal framework for agent-based distributed software development, and demonstrates its usefulness by applying the framework to the development of a requirements management system.
18329174
Enhancing 3D Graphics on Mobile Devices by Image-Based Rendering
Compared to a personal computer, mobile devices typically have weaker processing power, less memory capacity, and lower resolution of display. While the former two factors are clearly disadvantages for 3D graphics applications running on mobile devices, the display factor could be turned into an advantage instead. However the traditional 3D graphics pipeline cannot take advantage of the smaller display because its run time depends mostly on the number of polygons to be rendered. In contrast, the run time of image-based rendering methods depends mainly on the display resolution. Therefore it is well suited for mobile devices. Furthermore, we may use the network connection to build a client-server framework, which allows us to integrate with nonimage-based rendering programs. We present our system framework and the experiment results on PocketPC® based devices in this work.
8773045
Characterizing and Exploiting Reference Locality in Data Stream Applications
In this paper, we investigate a new approach to process queries in data stream applications. We show that reference locality characteristics of data streams could be exploited in the design of superior and flexible data stream query processing techniques. We identify two different causes of reference locality: popularity over long time scales and temporal correlations over shorter time scales. An elegant mathematical model is shown to precisely quantify the degree of those sources of locality. Furthermore, we analyze the impact of locality-awareness on achievable performance gains over traditional algorithms on applications such asMAX-subset approximate sliding window join and approximate count estimation. In a comprehensive experimental study, we compare several existing algorithms against our locality-aware algorithms over a number of real datasets. The results validate the usefulness and efficiency of our approach.
36323277
Event-Based Traceability for Managing Evolutionary Change
Although the benefits of requirements traceability are widely recognized, the actual practice of maintaining a traceability scheme is not always entirely successful. The traceability infrastructure underlying a software system tends to erode over its lifetime, as time-pressured practitioners fail to consistently maintain links and update impacted artifacts each time a change occurs, even with the support of automated systems. This paper proposes a new method of traceability based upon event-notification and is applicable even in a heterogeneous and globally distributed development environment. Traceable artifacts are no longer tightly coupled but are linked through an event service, which creates an environment in which change is handled more efficiently, and artifacts and their related links are maintained in a restorable state. The method also supports enhanced project management for the process of updating and maintaining the system artifacts.
18643244
An Empirical Performance Study on PSIM
It is well known that errors caught in the early stages of system development life cycle greatly helped reduce the expense for later error fixing and mitigate risks and complications. Performance analysis is one of the methods to ensure satisfactory system performance that can avoid redesign and patch in the later stage of system development when performance problems emerge. Much work has been done to address such concerns collectively known as the 'performance engineering' problem. However, a comprehensive method is still needed to provide an end-to-end support for performance evaluation on software architecture design. Automated tools to support the method must be developed, and its validation must be carefully planned and conducted. In response to this need, we propose our approach, PSIM (performance simulation and modeling). PSIM is a performance simulation and modeling tool that integrated performance properties into software architecture specifications expressed in several major UML diagrams. PSIM models can be transformed into Colored GSPN (colored generalized stochastic Petri nets) via an automated tool. As a result, the Colored GSPN models can be simulated to perform model-based performance evaluation. In this paper PSIM is first briefly reviewed and illustrated through modeling a web-based electronic conferencing system, called M-Net, to derive performance metrics. We then conduct runtime performance testing to the implementation of M-Net and compare the simulation results against the runtime testing data. PSIM is shown to be effective in predicting system performance and in identifying system performance bottlenecks through this experimentation.