Resin-EE Features

Overview

When you're building dynamic Web sites using JSP or servlet technologies, two issues quickly come to the forefront: scalability and database access. As the traffic to a Web site increases, there comes a time when all of the functionality overwhelms even the fastest processor. In these instances, you need to change the single-tier architecture—Web, business, and database functionality all on one machine—so that different functionality is hosted on different machines. One of the most popular architectures is called three-tier, where Web, business, and database tasks are handled on three different machines. While you can create JSP and servlet pages to work in a three-tier environment by themselves, a better solution is to use Enterprise JavaBeans (EJBs). There is quite a bit of debate on whether a three-tier environment using EJBs is a good architecture or not. One of the primary issues is the volume of network communication that must take place to transfer data from the first tier to the second, then to the third, and finally back again. One of the purposes of Resin-EE is to create an environment where the remote calls and data transfer aren't needed.

The second issue that Web sites encounter is the hardcoding of SQL statements for database access. As you modify the underlying database, add or expand tables, or add new features, you have to change the SQL as well. When the SQL is strung throughout the application, maintenance becomes a real problem. EJBs come to the rescue here by encapsulating most database access within Java objects. When using EJBs, you employ various frameworks to handle all of the SQL automatically through the entity bean. By simply instantiating an entity bean, you gain transparent access to the database. Whether the Web site is on a single server or a hundred, EJBs simplify database access.

In this chapter, we introduce a product from Caucho called Resin-EE. Resin-EE is a server designed to use some of the best features of EJBs when you're developing smaller, mainly single-tier Web sites, although you can use it for larger sites as well.