1.1 J2EE Web site topologies and caching
J2EE-based systems commonly incorporate the Model-View-Controller (MVC) design pattern, where the responsibilities of an application are assigned to layers of code that support the user interface (View), business logic (Controller), and data access (Model).
Similarly, the physical topology of the hardware that serves the application is often split into tiers:
- An edge tier made up of caching proxies and/or load balancers
- A Web tier consisting of Web servers such as Apache or IBM HTTP Server
- An application tier for managing data
The data or persistence tier for storing and retrieving data
In these types of distributed architectures caching can be used to maximize the performance and minimize the workload of each tier, resulting in substantial performance improvements. Cached items fall into two groups:
- Static data, such as HTML, images, and Java™ Script files
Dynamically created data that contains the output results from the runtime program execution of code components, such as servlets and JSPs.