Definition: Queue Structure is the crucial element of a queuing system, as it shows the queue discipline, which means the order in which the customers are picked from the queue for the service. Simply, the way the customer is selected from the waiting line for service is shown by the queue structure.
The customers can be chosen from the queue in one of the following ways:
- First-come-first-served: When the services are rendered to the customers in order of their arrival, the queue discipline is the first-come-first-served type. Simply, serving the customer first, who comes first to the service facility. For example, At the movie ticket counter, a person who came first will get the tickets first.
- Last-come-first served: It simply means, the person who comes last will be served first. Sometimes the customers are serviced in the order reverse of the order in which they enter the service facility. For example, a pile of files, the file that comes in the last will be read first.
- Service-in-random-order (SIRO): Under this type of queue structure, the customer is chosen for service randomly and hence all the customers are equally likely to be selected. Therefore, the time of arrival of the customer has no consequence on the selection of the customer.
- Priority Service: In this system, the customers are serviced on a priority basis. Customers may be called due to some identifiable characteristic (length of job, for example) for service. Generally, it is seen that VIPs are given preference over the other patients in the hospital.
Thus, these are the ways in which an individual is selected from the queue depending on his arrival and the nature of service being offered.