Queuing system

Queuing Systems
Queuing theory establishes a powerful tool in modeling and performance analysis of many complex systems, such as computer networks, telecommunication systems, call centers, manufacturing systems and service systems. Many real systems can be modeled as networks of queues, such as the waiting line in a bank, a bus stop, waiting line in airport, material flow in factory, and signal flow in network. So, each of these simple systems consists of three major components:
• Entities:
Something that changes the state of the system. In many cases, particularly those involving service systems, the entity may be a person. In the customer service center, the entities are the customers. Entities do not necessarily have to be people; they can also be objects. Similarly, in the factory example, the entities are components waiting to be machined; entities can be signals waiting to be received in communication networks.
• Queues:
Queues are the simulation term for lines. Entities generally wait in a queue until it is their turn to be processed.
• Resources:
Processer or server that serves the entities those are in the queue. Example factory machines, computer processer, nodes in communication networks. The relationships among these components are illustrated in figure (1).