MACROMEDIA FLASH REMOTING MX-USING FLASH REMOTING FOR FLASH MX 2004 ACTIONSCRIPT 2.0 Specifications download pdf (Page 36)

This is the Title of the Book, eMatter Edition

Chapter 1: Introduction to Flash Remoting

Presentation Tier

The presentation tier is responsible for the application’s user interface (UI) and any

client-side logic that is needed, such as client-side data validation. It communicates

with the middle tier by sending and loading data on a request-driven basis. In most

cases, the presentation layer consists of a Flash file embedded within an HTML page,

but it can also be a Flash Standalone Projector running on the desktop, or even a

Flash sprite within a Director Projector.

Middle Tier

The middle tier sits between the presentation layer and the data source. Its primary

role is to separate the presentation tier from the data tier and provide access to the

data tier from the Flash Player. The core application logic is also normally imple-

mented in the middle tier. This frees the client to do what it does best—presenta-

tion—and frees the server to do what it does best—communicate with databases and

manipulate data.

The middle tier resides on the server and can be implemented with various technolo-

gies, such as ColdFusion, ASP.NET, and Java. In addition, the middle tier can con-

sist of multiple levels, each adding a layer of abstraction from those immediately

above and below it.

In Flash 5, it was common to have a multitiered middle layer, with the uppermost

layer serializing and deserializing data to and from the Flash Player, as shown in

Figure 1-8.

However, using Flash Remoting and Flash Player 6 or later, this logic is handled by

the Flash Remoting gateway, sitting on the server atop the middle tier, as shown in

Figure 1-9. Flash Remoting eliminates the need to write Flash-specific code in the

middle tier.

Data Tier

The data tier is the lowest level of the architecture and is responsible for managing

the application’s data, as well as the data’s persistence. The data source resides on

the server side and can be implemented as a database (such as SQL Server, DB2,

MySQL, or Oracle), XML file, comma-separated file, and so forth. Client-specific

data, such as user interface preferences, can be stored on the client side using cook-

ies or ActionScript local shared objects (LSOs). Whether this data is stored on the

client side or in the data tier on the server side depends primarily on the importance

of the data to the functionality of the application, with application-critical data gen-

erally being stored on the server, which is considered more reliable.

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MACROMEDIA FLASH REMOTING MX-USING FLASH REMOTING FOR FLASH MX 2004 ACTIONSCRIPT 2.0 Specifications Page 36