Security Issues in Distributed Computing System Models

Background

A distributed computing system is the system architecture that makes a collection of heterogeneous computers or workstations act and behave as being one single computing system. In such a computing environment, users can uniformly access local or remote resources, and run processes from anywhere in the system (Firdhous, 2011). A distributed system is a collection of (homogenous/heterogeneous) automata interconnected by a network. Its distribution is transparent to the user. So the system appears as one local machine. In a distributed system, the nodes communicate by sending and receiving messages over the network. Various distributed resources (i.e. files and printers) are shared across the network between the nodes in the form of network services that are provided by servers. Individual processes, clients, direct request the appropriate server in order to access recourses. Thus, a distributed system has three primary characteristics: multiple nodes, interconnections, and shared states. This section provides an introduction to the distributed systems and how to characterize them.

Coulouris et al. (2012) have defined a distributed system as “a system where the hardware and software components have been installed in geographically dispersed computers that coordinate and collaborate their actions by passing messages between them”. Tanenbaum & Steen (2007) have defined a distributed system as “a collection of systems that appears to the users as a single system”. Combining these definitions, it could be stated that a distributed system is an application that communicates with multiple dispersed hardware and software in order to coordinate the actions of multiple processes running on different autonomous computers over a communication network, so that all components (hardware and software) cooperate together to perform a set of related tasks that are targeted towards a common objective (Firdhous, 2011).