As a platform, Java has been evolving a set of mechanisms that can capitalize on the inherent strengths of server-side Java. The servlet API, which connects browsers to Web-based services more adroitly than the Web's conventional Common Gateway Interface mechanism. Java Server Pages technology. Similar to Microsoft 's Active Server Pages, it injects Java logic into HTML page templates. Enterprise JavaBeans, which define a standard component architecture for deployment of Java-based business logic.
Application servers create and maintain user sessions.
Network services also need to know which logged-in user can see which Web page. Application servers can define and enforce access-control scenarios. High-performance database connectivity. An application server can create a pool of database connections, then reuse them to ensure speedy access to data. A network service can't fail.