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Dr. Tomasz Rak
Department of Computer and Control Engineering; Rzeszow University of Technology

Basic Info


Research Keywords & Expertise

0 Internet Systems
0 Modeling and Simulation
0 DISTRIBUTED COMPUTING
0 Cluster Computing
0 ARTIFICIAL INTELLIGENCE AND CONTROLS

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Journal article
Published: 24 June 2020 in Information
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Web systems are becoming more and more popular. An efficiently working network system is the basis for the functioning of every enterprise. Performance models are powerful tools for performance prediction. The creation of performance models requires significant effort. In the article, we want to present various performance models of customer and Web systems. In particular, we want to examine a system behaviour related to different flow routes of clients in the system. Therefore we propose Queueing Petri Nets, the new modeling methodology for dealing with performance issues of production systems. We follow the simulation-based approach. We consider 25 different models to check performance. Then we evaluate them based on the proposed metrics. The validation results show that the model is able to predict the performance with a relative error lower than 20%. Our evaluation shows that prepared models can reduce the effort of production system preparation. The resulting performance model can predict the system behaviour in a particular layer at the indicated load.

ACS Style

Tomasz Rak. Modeling Web Client and System Behavior. Information 2020, 11, 337 .

AMA Style

Tomasz Rak. Modeling Web Client and System Behavior. Information. 2020; 11 (6):337.

Chicago/Turabian Style

Tomasz Rak. 2020. "Modeling Web Client and System Behavior." Information 11, no. 6: 337.

Conference paper
Published: 05 June 2019 in Communications in Computer and Information Science
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Simulation studies for Web systems have been carried out by many academic researchers and practitioners. Models are often less time-consuming to develop and run production system. Performance Engineering is done to determine the system performance. In the paper various performance models of Cluster-based Web Systems are discussed, as well as their influence on response time. The Queueing Petri Nets simulations are based on different loads, but also on changing environmental parameters and system structures. A novelty in this approach is the use of two client-classes related to customer behavior and routes in the system. In all cases Web system architectures include clusters are taken into consideration. Simulation results obtained from this models are compared with data from a real system and show good accuracy.

ACS Style

Tomasz Rak. Cluster-Based Web System Models for Different Classes of Clients in QPN. Communications in Computer and Information Science 2019, 347 -365.

AMA Style

Tomasz Rak. Cluster-Based Web System Models for Different Classes of Clients in QPN. Communications in Computer and Information Science. 2019; ():347-365.

Chicago/Turabian Style

Tomasz Rak. 2019. "Cluster-Based Web System Models for Different Classes of Clients in QPN." Communications in Computer and Information Science , no. : 347-365.

Conference paper
Published: 30 May 2017 in Programmieren für Ingenieure und Naturwissenschaftler
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In this paper, a performance model is used for studying distributed web systems (an J2EE web application with Oracle backend-database). Performance evaluation is done by obtaining load test measurements. Queueing Petri Nets (QPN) formalism supports modeling and performance analysis of distributed World Wide Web environments. The proposed distributed web systems modeling and design methodology has been applied for evaluation of several system architectures under different external loads. Experimental analysis is based on benchmark with realistic workload. Furthermore, performance analysis is done to determine the system response time.

ACS Style

Tomasz Rak. Performance Modeling Using Queueing Petri Nets. Programmieren für Ingenieure und Naturwissenschaftler 2017, 321 -335.

AMA Style

Tomasz Rak. Performance Modeling Using Queueing Petri Nets. Programmieren für Ingenieure und Naturwissenschaftler. 2017; ():321-335.

Chicago/Turabian Style

Tomasz Rak. 2017. "Performance Modeling Using Queueing Petri Nets." Programmieren für Ingenieure und Naturwissenschaftler , no. : 321-335.

Research article
Published: 16 September 2015 in Mathematical Problems in Engineering
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A performance model is used for studying distributed Web systems. Performance evaluation is done by obtaining load test measurements. Queueing Petri Nets formalism supports modeling and performance analysis of distributed World Wide Web environments. The proposed distributed Web systems modeling and design methodology have been applied in the evaluation of several system architectures under different external loads. Furthermore, performance analysis is done to determine the system response time.

ACS Style

Tomasz Rak. Response Time Analysis of Distributed Web Systems Using QPNs. Mathematical Problems in Engineering 2015, 2015, 1 -10.

AMA Style

Tomasz Rak. Response Time Analysis of Distributed Web Systems Using QPNs. Mathematical Problems in Engineering. 2015; 2015 ():1-10.

Chicago/Turabian Style

Tomasz Rak. 2015. "Response Time Analysis of Distributed Web Systems Using QPNs." Mathematical Problems in Engineering 2015, no. : 1-10.

Conference paper
Published: 29 September 2014 in Proceedings of the 2014 Federated Conference on Computer Science and Information Systems
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ACS Style

Tomasz Rak. Performance Analysis of Distributed Internet System Models using QPN Simulation. Proceedings of the 2014 Federated Conference on Computer Science and Information Systems 2014, 2, 769 -774.

AMA Style

Tomasz Rak. Performance Analysis of Distributed Internet System Models using QPN Simulation. Proceedings of the 2014 Federated Conference on Computer Science and Information Systems. 2014; 2 ():769-774.

Chicago/Turabian Style

Tomasz Rak. 2014. "Performance Analysis of Distributed Internet System Models using QPN Simulation." Proceedings of the 2014 Federated Conference on Computer Science and Information Systems 2, no. : 769-774.

Book chapter
Published: 25 September 2014 in Information Sciences and Systems 2014
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The paper presents the cluster-based web system for that the time rate of changing a system offer is compared to the users’ interaction time with a system. Systems with rapidly changing offer are used in different domains including the electronic trading to build scalable distributed systems. In the paper, such systems are modeled by queueing Petri nets. The aim of this work was to develop simulation models of Internet system by queueing Petri net modeling environment tool to performance analysis. Developed models allow to evaluate their performance (e.g., response time). In our experimental analysis, we use clustered web environment with Apache DayTrader benchmark as an e-trading system. It helped to determine the parameters for the simulation models and then to verify the simulation results. The paper includes the selected results of models simulation. Our approach predicts the performance of the given application deploy on a selected platform.

ACS Style

Tomasz Rak. Performance Analysis of Cluster-Based Web System Using the QPN Models. Information Sciences and Systems 2014 2014, 239 -247.

AMA Style

Tomasz Rak. Performance Analysis of Cluster-Based Web System Using the QPN Models. Information Sciences and Systems 2014. 2014; ():239-247.

Chicago/Turabian Style

Tomasz Rak. 2014. "Performance Analysis of Cluster-Based Web System Using the QPN Models." Information Sciences and Systems 2014 , no. : 239-247.

Conference paper
Published: 01 January 2012 in Computer Vision
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This paper presents the performance analysis of interactive Internet systems, for which the time rate of system offer change is comparable to the users interaction time with the system. In this paper such systems class is called Interactive Internet Systems with Dynamically Changing Offers (IISDCO). In IISDCO systems an offer change may cause cancellation of the started but incomplete transactions. The necessity of cancellation can result from the sale of a set of resources (goods sold) which is getting exhausted or whose price has changed. This paper includes a performance analysis of an on-line stock exchange system (sample of IISDCO). For the analysis we used models in the form of Time Coloured Petri Nets (TCPNs). We also reviewed the proposed models on the example of the Internet on-line stock exchange system.

ACS Style

Tomasz Rak; Jan Werewka. Performance Analysis of Interactive Internet Systems for a Class of Systems with Dynamically Changing Offers. Computer Vision 2012, 7054, 109 -123.

AMA Style

Tomasz Rak, Jan Werewka. Performance Analysis of Interactive Internet Systems for a Class of Systems with Dynamically Changing Offers. Computer Vision. 2012; 7054 ():109-123.

Chicago/Turabian Style

Tomasz Rak; Jan Werewka. 2012. "Performance Analysis of Interactive Internet Systems for a Class of Systems with Dynamically Changing Offers." Computer Vision 7054, no. : 109-123.

Conference paper
Published: 01 October 2008 in 2008 International Multiconference on Computer Science and Information Technology
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This paper presents a timed coloured Petri nets based programming tool that supports modeling and performance analysis of distributed World Wide Web environments. A distributed Internet system model, initially described in compliance with queueing theory (QT) rules, is mapped onto the Timed coloured petri net (TCPN) structure by means of queueing system templates. Then, it is executed and analyzed using design/CPN toolset. The proposed distributed Internet systems modeling and design methodology has been applied for evaluation of several system architectures under different external loads.

ACS Style

Tomasz Rak; Slawomir Samolej. Distributed Internet systems modeling using TCPNs. 2008 International Multiconference on Computer Science and Information Technology 2008, 559 -566.

AMA Style

Tomasz Rak, Slawomir Samolej. Distributed Internet systems modeling using TCPNs. 2008 International Multiconference on Computer Science and Information Technology. 2008; ():559-566.

Chicago/Turabian Style

Tomasz Rak; Slawomir Samolej. 2008. "Distributed Internet systems modeling using TCPNs." 2008 International Multiconference on Computer Science and Information Technology , no. : 559-566.