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.
45899286
Computer Supported Cooperative Work Oriented Architecture
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. >
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>>
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>>
17140893
An Aspect-Oriented Approach to Resource Composition in Petri net-based Software Architectural Models
Petri net has been widely used for modeling software systems due to its mathematical soundness and support of various tools. In many cases, performance-related analyses of Petri net for a software system need to consider the resource limitations caused by a specific platform. In terms of aspect-oriented approach, the interference of various resources scattered across a software system can be regarded as a specific concern that is only necessary during its performance-related analysis process. To capture the interactions of resources within the Petri net-based software architectural model, we propose an aspect-oriented resource composition model and the XML-based representation language called the resource extension markup language (ReML) for its description. In our approach, one or more resource composition models can be developed and described in ReML separately from the development of base software architectural models. Through the weaving process, a resource composition model can be applied to extend several Petri net-based software architectural models. The resource weaver generates an augmented Petri net used for analyzing performance characteristics of the extended software architectural model with resource interactions. Our aspect-oriented approach facilitates selecting an optimal or superior resource composition model for a software architectural model, and vice versa, which is illustrated using two exemplary server models
39549662
Categorical Data Visualization and Clustering Using Subjective Factors
Clustering is an important data mining problem. However, most earlier work on clustering focused on numeric attributes which have a natural ordering to their attribute values. Recently, clustering data with categorical attributes, whose attribute values do not have a natural ordering, has received more attention. A common issue in cluster analysis is that there is no single correct answer to the number of clusters, since cluster analysis involves human subjective judgement. Interactive visualization is one of the methods where users can decide a proper clustering parameters. In this paper, a new clustering approach called CDCS (Categorical Data Clustering with Subjective factors) is introduced, where a visualization tool for clustered categorical data is developed such that the result of adjusting parameters is instantly reflected. The experiment shows that CDCS generates high quality clusters compared to other typical algorithms.
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.
10778870
An empirical performance study for validating a performance analysis approach: PSIM
Performance analysis gains more attention in recent years by researchers who focus their study on the early software development stages to mitigate the risk of redesign as problems emerge later. Previously we proposed PSIM (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 and the colored GSPN models can then be simulated to perform model-based performance evaluation. In this paper we briefly review the PSIM approach and apply it to model a Web-based 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 data to runtime testing data. The comparison results show the effectiveness of the PSIM method in predicting system performance and identifying system performance bottlenecks.
36174550
Service-oriented design with aspects (SODA)
In this paper, we introduce a service-oriented design method by integrating the concept of aspects, which is called service-oriented design with aspects (SODA) in order to utilize services and aspects as fundamental and abstract elements in the design phase of software lifecycle. The service model is represented in the structural and behavior views using UML with its extension mechanism and Petri net respectively. Aspects are used to capture service-specific concerns required for delivering high-quality and user-friendly services. By weaving services and aspects, we can generate various versions of a service system as well as their Petri net based service semantics that also facilitates the verification of service design results. We exemplify a service design result of SODA by applying it to a supply-chain management application.