Java Enterprise Best Practices

Efficient Distributed Computing Architecture

High-performance architecture for enterprise systems consists of one or more frontend load balancers (the Front Controller design pattern) distributing requests to a cluster of middle-tier web application servers running J2EE, with a database behind this middle tier. Components designed to operate asynchronously with message queues holding requests for the components optimize the throughput of the system (the Message Façade design pattern). Server management of client socket connections should use the java.nio package classes, and in particular sockets should be multiplexed with the Selector class. Load balancing is efficiently supported using multiplexed I/O (the Reactor design pattern). (Typically, the application server manages sockets transparently in the application, but if your application manages sockets directly, do it with NIO multiplexing.)

In addition, these main architectural components should be supported with caches, resource pools, optimized database access, and a performance-monitoring subsystem, and should have no single point of failure. Caches and resource pools should be made tunable by altering configuration parameters—i.e., they shouldn’t require code tuning. Resource pools are recommended only for resources that are expensive to replace or need limiting, such as threads and database connections. Database access optimization is made simpler if there is a separate database access layer (the Data Access Object ...