Architecture explained
It is best to learn the intricacies of system architecture with the help of a diagram. For the benefit of a brief but meaningful explanation on the JIRA architecture, let us have a quick look (or a long stare, whichever you are more comfortable with!) at the following diagram:
JIRA is a web application built using the MVC architecture. It is fully written in Java and is deployed as a WAR file into a Java Servlet Container such as Tomcat.
The majority of the JIRA core functionality revolves around the JIRA Utility and Manager Classes, which thus becomes the heart of JIRA. It also interacts with a lot of third-party components, which we saw earlier, to deliver powerful functionalities such as workflows, permissions, user management, and searching.
As with any other web application, let us start with the incoming requests. Users interact with JIRA using web browsers, but there are other ways to interact with JIRA, such as using the Jelly scripts or by making remote calls...
