Application server
A software platform that provides the services and infrastructure required to develop
and deploy middle-tier applications. Middle-tier applications implement the business logic
necessary to provide web clients with access to enterprise information systems. In a
multi-tier architecture, an application server sits beside a web server or between a web
server and enterprise information systems. Application servers provide the middleware for
enterprise systems. JBoss, WebLogic and WebSphere are J2EE application servers.