Using Flex in an n-tier application model

By definition, enterprise applications are multitiered, where each tier brings specific benefits to the application design. A tiered architecture provides natural access points for integration with existing and future systems.

Each tier serves a specific purpose, and lets you divide the functionality of a business application into discrete components that you can implement independently from each other. For example, the following figure shows the tiers of a five-tier application model:

An n-tier architecture offers the following advantages:

• The tiers, or even components of the tiers, can be distributed across multiple hardware systems to improve system scalability and performance.
• The client and presentation tiers shield clients from the complexities of accessing the enterprise data store.
• You can distribute application development across your development group. For example, JSP developers are typically concerned with information presentation rather than with implementing business rules. Conversely, EJB developers are concerned with data access and manipulation, but not with presentation.

In traditional n-tier applications, the presentation tier logic executes on the server, so every client interaction requires a data transfer between the client and server.

Flex adds new functionality and options to the n-tier model. The following figure shows the same five tiers for a Flex application:

In Flex, Flash Player provides the platform for interface development so that both client and presentation tier logic executes on the client computer. Flex applications that execute in Flash Player process user interactions; perform data validation; issue HTTP, SOAP, AMF requests; and perform other operations previously performed on the server. Because Flash Player runs consistently across all major operating systems and browsers, you do not have to program your applications for a specific browser or platform.

Note: You can still develop presentation-tier logic for the server as part of your application, and connect to that logic from the client.

The Flex server executes on a J2EE platform or servlet container, and provides the integration point for Flex applications to server-side functionality. The Flex server also includes the Flex compiler, caching mechanism, and web service proxy.

You do not need to modify the business and integration tiers to integrate with Flex. This means that you code the business and back-end functionality in the same way you did for your existing applications. Flex lets you connect to your back-end systems and application logic using web services, HTTP, EJBs, or other methods.

Version 1.5

Send me an e-mail when comments are added to this page | Comment Report

Current page: http://livedocs.adobe.com/flex/15/flex_docs_en/00000003.htm

Add Comment