Chapter 6 Queueing Networks Modelling Software (QNs) and Computing Language(s)

Transcription

1 Chapter 6 Queueing Networks Modelling Software (QNs) and Computing Language(s) 6.1 Introduction This chapter, reviews the evaluation of queueing networks software (QNs) and computing language(s) and their use in queueing theory modelling. There are different groups of software tools. Some queueing networks software require a good knowledge of the queueing theory, while other networks software designed for the model development process which is automated. (e.g.: for manufacturing). For the analysis of quaueing networks, the developed theory motivated the development of many software packages for the purpose. These software packages require a good level of familiarity of the theory of queues. There are some early packages, which are based on original algorithms. We are considering some early packages, some of them are given below: (i) (ii) (iii) QNA (Queueing Network Analyzer): This package was proposed by Whitt [1983]. QNET: This is another software package for performance analysis of queueing networks. This package is the implementation of the analysis algorithm based on Brownian approximation of queueing networks. Dai and Harrison [1993], Harrison and Nguyen [1990]. This package is written in text mode and its source code is available for free download. PEPSY-QNS / Win PEPSY: This package was developed at the University of Erlangen Nurnberg in early 1990's. This package includes more than 50 different algorithms. The windows version (Win-PEPSY) has some special characteristics.

2 (iv) QNAT (Queueing Network Analysis Tool): This is a windows graphical software package for analysing a large variety of quaueing networks. QNAT uses MATHEMATICA as its computing platform and can handle general configurations of open and closed networks, of both finite and infinite capacity of queues. These both open and closed networks are shown in the following figures : 6.1 and in 6.2 Figure 6.1: Open queueing network. Figure 6.2: Closed queueing network. (v) RAQS (Rapid Analysis of Queueing Systems): This software is windows graphical queueing software. Kamath et al. [1995]. This software is based on the Whitt'e QNA method. 112

3 (vi) (vii) QTS (Queueing Theory Software): This Software is based on the textbook of Gross et al. [2008]. This software is written as excel spreadsheet for solving a wide range of queueing model and other probability models like Marker chains, birth and death processes, etc. In this software the user has all in one model. JMT (Java Modeling Tools): This is a free open source suite implementing several algorithms for the Excel, asymptotic and simulative analysis of queueing network models. Java Modeling Tools (JMT): version 8.0 is a suite of applications developed by Politecnico, di. Milano, and released under GPL license. The current stable version of the suite encompasses six Java applications given as follows: 1. JSIM graph: Queueing network models simulator with graphical user interface. 2. JSIM wiz: Queueing network models simulator with Wizard-based user interface. 3. JMVA: Mean value analysis of queueing network models. 4. JABA: Asymptotic analysis of queueing network models. 5. JWAT: Workload analysis from log and usage data. 6. JMCH: Markov Chain simulator (didectic tool). The above packages are freely available for download (while some are open source of QTS, JMT, etc.). 113

4 We explain download links for some free QN software which are given as follows: QN-Software Win-PEPSI QTS JMT RAQS QNAT Download Links Table 6.1: Download links for some QN software Some other queueing network software, we have included in APPENDIX-B. 6.2 Queueing Software's: Use and Applications In the last few years there is a growing interest in integrating performance evaluation tools in early stages of software development, life cycle and queueing network models have been used for quantitative analysis and validation of software system. Queueing networks are useful to model and measure the performance of manufacturing systems and also complex service processes. Queueing software can be used by industrial analysts, managers and educators. It is a good tool to help students to understand factory physics along with modeling and analysis techniques, de Treville and Van Ackere [2006]. Close contact between researchers and industrial users has been critical to the growth in use of QN, software. Along with better linkages to Operational Systems, which will ensure continue growth of manufacturing applications of queueing software, Suri et al. [1995]. The use of the queueing software are in education may help to enlarge its use in companies. When students realize the usefulness of these software tools, it becomes natural and practical, they will use, it after they join work in the industry. The process of a software package depends upon many factors 114

5 other than the accuracy of its computational method. Users look for a powerful tool with evidence of efficiency but also a user friendly, easy to learn and well supported product. The ability of the software to import / export data from / to other packages allows the users to gain in time and effort. When using available software libraries, it is still necessary to develop programs representing the behaviour of a modeled system. The behaviour of each modeled component, the connections among the components (how a job moves from one component to another), and the way in which a waiting queue of jobs is processed must be coded into simulation. To solve practical problems, the first step is to identify the appropriate queuing system and then to calculate the performance measures. The level of modeling depends on the assumptions. It is recommended to start with simple system and, then if the results do not fit to the problem, continue to the more complicated software packages. 6.3 Computing Language(s) MATLAB is a high level technical computing language and interacting environment data visualization, data analysis, and numerical computation. It manipulates every data in the form of matrix. So, it is Matrix Laboratory abbreviated as MATLAB. Using MATLAB, We can solve technical computing problems faster than with traditional programming languages such as C, C++ and Fortran, Linux, Solaris and Mac, etc. MATLAB's functionality can be extended by adding different tool boxes for optimization, data analysis, signal processing, financial modeling etc. We have find out numerical results in our published paper, Awadhesh Kumar Mishra and R.K. Shrivastava [2014]: "Queueing Analysis of Machine Repair System with Warm Spares and Multiple N-Policy Vacations for Repairmen". International Journal of Mathematical Sciences (IJMS), Vol. 13, No. 1-2, pp We have used MATLAB Our original Codes of MATLAB programming are included in Appendix-A of the thesis. 115

6 6.4 Summary In this chapter, we have developed and explained, Queueing Networks Software and Computing Language(s). We have developed many software packages which are used for the analysis of queueing networks. Queueing software can be used by industrial analysis, managers and educators. Researchers and industrial users find the growth in the use of QN software. In our calculation, finding numerical results, we have used MATLAB , Codes are placed in the Appendix-A of the thesis. 116