International Journal of Computer Applications (0975 – 8887) Volume 60– No.3, December 2012 20 Modeling Aspects for Step and Bus Topologies under Distributed Computing System Taskeen Zaidi Deptt. of Computer Science Babasaheb Bhimrao Ambedkar University Vidya Vihar, Rae Bareli, Lucknow Vipin Saxena Professor, Deptt. of Computer Science Babasaheb Bhimrao Ambedkar University Vidya Vihar, Rae Bareli Road, Lucknow ABSTRACT The distributed computing approach has the several advantages over the old centralized computing approach like reduction of execution time and low cost involvement. Many researchers have applied the modeling concepts for the distributed computing system. The most popular approach is the object-oriented modeling also known as Unified Modeling Language (UML) approach which is a platform independent to any programming language. In the present work, Unified Modeling Language (UML) is used for the various aspects used in the distributed computing system. This paper consists of the modeling of newly developed step topology and compared with the bus topology under distributed computing system. UML activity diagrams are designed for these topologies and the diameters of bus and step topology are also computed by varying the nodes through hope count and represented in the form of table and graph. Keywords Distributed computing system, UML, Activity diagram, Step topology, Diameter. 1. INTRODUCTION Topology plays an important role for static interconnection of the computer systems. In the literature, many topologies appeared but some of them like star, bus are frequently used by the network administrator for establishment of the computer centre. In this connection, an important reference Tanenbaum [1] has written a famous book on computer networks which describes the generation of computer networks including network topologies, adhoc networks, wireless networks etc. Since, many of the software industries are using the concept of the distributed computing systems for execution of the tasks on the local area network which are well described by Frouzan [2] and it consists of detailed processing of networks, structures, models, classification and categories of networks. The distributed computing algorithms for execution of the processes are available in Milenkovic [3] who has also explained security threats caused by users and providers on the network. In the current scenario and faster transfer of the data, dynamic connections are also used by the network administrators which are based on the various types of topologies like hyper cube, digital bus, etc. and these are available in Hwang [4]. If one is transferring the data from one machine to the another machine, then the architecture of the computer systems play an important role for transferring of the data and these are well described by Mano[5]. Patterson et al. [6] has described the architectures and recent technologies used in the computers. Sharing of resources, data, files, audios, videos and various information in distributed environment as well as mutual exclusion of tasks for static connection are available in[7-8]. On the other hand, software and hardware architecture research problems can be solved through the modeling language. Due to evolution of the object-oriented technologies, a well known modeling language called as Unified Modeling Language [UML] is used by the various researchers and this modeling language has been created by the OMG group [9-10]. This language is also used for computing the various performance metrics to create the applications for parallel and distributed systems which have been proposed by [11-12]. Booch [13] has described the various stages of the development of the UML and currently version of the UML is used by the various researchers is 2.0. The use of UML for solving the research problem, how to draw read and create projects to make it effective are well explained in [14]. The various prospects of UML to create effective projects are illustrated by Gomaa [15]. Recently, Saxena and Zaidi [16] have proposed a step topology for static interconnection of computer system under distributed environment. In India, distributed computing approach is used to establish the National Knowledge Network (NKN) project with main objective to connect the higher learning Institutions for sharing the knowledge. Recently, Saxena and Zaidi [17] have studies a case study for computing the % utilization of NKN alongwith the advantages and difficulties faced under this project. Saxena et al. [18] have also measured the performance of processors for different object-oriented software systems under distributed environment. UML modeling of a protocol for establishing the mutual exclusion in the distributed computing system has been done by Saxena and Arora [19]. Ladder topology which is used for the circuit designing and later on performance of this topology is evaluated by the authors [20-21]. Performance of various static and network topologies have been computed by Saxena and Raj [22-23]. Saxena and Zaidi[24] has computed the performance of Endian operating system in which user’s identification has been monitored by internet protocol (version4) and users are connected under static step topology. On the basis of above, the present work emphasized on the modeling aspects for the step topology and it is compared with the similar kind of famous bus topology. The UML activity and class diagrams are designed for these two topologies used for the static interconnection under the distributed computing environment. Before this, a process id is created for the execution of the processes on the static interconnection and later on a comparison between bus and step topologies are also explained in the form of table and graph. 2. BACKGROUND 2.1 A Distributed System Distributed system is a collection of various devices which are communicated to each other by message passing techniques. Devices like laptops, ipads, pdas, etc are connected under