Multitiered Architecture Design

Java Enterprise System is well-suited for multitiered architecture design, where services are placed in tiers according to the functionality they provide. Each service is logically independent and can be accessed by services in either the same tier or a different tier. The following figure depicts a multitiered architecture model for enterprise applications, illustrating the client, presentation, business service, and data tiers.

Figure 4–3 Multitiered Architecture Model

The following table describes the logical tiers depicted in Multitiered Architecture Design.

Table 4–4 Logical Tiers in a Multitiered Architecture

Tier	Description
Client tier	Contains client applications that present information to end users. For Java Enterprise System, these applications are typically mail clients, web browsers, or mobile access clients.
Presentation tier	Provides services that display data to end users, allowing users to process and manipulate the presentation. For example, a web mail client or Portal Server component allows users to modify the presentation of information they receive.
Business service tier	Provides back-end services that typically retrieve data from the data tier to provide to other services within the presentation or business service tiers or directly to clients in the client tier. For example, Access Manager provides identity services to other Java Enterprise System components.
Data tier	Provides database services accessed by services within the presentation tier or business service tier. For example, Directory Server provides LDAP directory access to other services.

Multitiered architecture design provides several advantages. During the deployment design phase, the placement of services according to functionality in a multitiered architecture helps you determine how to distribute services in your network. You also can see how components within the architecture access services of other components. This visualization helps you plan for availability, scalability, security, and other quality of service solutions.