layout	pattern
title	Priority Queue Pattern
folder	priority-queue
permalink	/patterns/priority-queue/
categories	Behavioral
tags	Decoupling Cloud distributed

Intent

Prioritize requests sent to services so that requests with a higher priority are received and processed more quickly than those of a lower priority. This pattern is useful in applications that offer different service level guarantees to individual clients.

Explanation

Applications may delegate specific tasks to other services; for example, to perform background processing or to integrate with other applications or services. In the cloud, a message queue is typically used to delegate tasks to background processing. In many cases the order in which requests are received by a service is not important. However, in some cases it may be necessary to prioritize specific requests. These requests should be processed earlier than others of a lower priority that may have been sent previously by the application.

Class diagram

Applicability

Use the Priority Queue pattern when

• The system must handle multiple tasks that might have different priorities.
• Different users or tenants should be served with different priority..

Credits

• Priority Queue pattern