An application server is a mixed framework of software that allows both the creation of web applications and a server environment to run them. It can often be a complex stack of different computational elements running specific tasks that need to work as one to power multiple clouds and web-based software and application. Sitting between the primary web-based server tier and the back-end tier of a database server, the application server is essentially a go-between for the database server and the users of the business or consumer apps it supports through putting various protocols and application programming interfaces (APIs) to use. An application server is designed to install, operate and host applications and associated services for end users, IT services and organizations and facilitates the hosting and delivery of high-end consumer or business applications.
Depending on what is installed, an application server can be classified in a number of ways, such as a web server, database application server, general purpose application server or enterprise application server. It's commonly paired with a web server or contains a web server, which means the two can be converged and named a web application server. It is also versatile enough to be used with other application servers simultaneously. Application servers can also contain their own graphical user interfaces for management through PCs, but they can also take care of their own resources, as well as transaction processing, messaging, resource and connection pooling, and performing security tasks.
For high-end requirements, applications servers tend to have high availability monitoring, clustering, load balancing, integrated redundancy, and high-performance distributed application services as well as support for complicated database access. Among the popular application server platforms are J2EE, WebLogic, Glassfish, JBoss Enterprise Application Platform, Apache Tomcat, and Apache Geronimo, to name but a few.
Application servers are best put to use when there is the need to integrate with databases and servers, for example, web servers, which have already been set up and are part of an organisation's existing IT infrastructure.