Business logic components, connection, transaction and security management, component instance pooling, clustering, load balancing, and fail-safe mechanisms are some of the important features that an application server should possess.
A2:
In order to handle a huge load of user requests, multiple application servers are grouped together, often on different machines, with a single point of entry for incoming user requests. This is called clustering.
A3:
Component instance pooling involves the creation of multiple instances of a component by the application server before the component is used or accessed. The EJB container in WebLogic Server 7.0 supports component pooling for EJBs. Similarly, the Servlet engine in WebLogic Server 7.0 also supports pooling of servlet instances.
