MACROMEDIA FLASH REMOTING MX-USING FLASH REMOTING FOR FLASH MX 2004 ACTIONSCRIPT 2.0 Specifications download pdf (Page 9)

This is the Title of the Book, eMatter Edition

How Does Flash Remoting Work?

Action Message Format

Flash 5 movies could send XML or name/value pairs across HTTP. Although these

packets could be parsed automatically by Flash or manually by the developer using

custom ActionScript, parsing could be slow because all XML data is sent as text

strings encased by cumbersome tags. Flash Remoting is able to handle complex

datatypes, such as objects, structures, arrays, and recordsets. A proprietary format

was needed to transfer information back and forth between the Flash movie and the

application server.

The protocol used for communication between the Flash Remoting gateway and the

Flash Player is Action Message Format (AMF). AMF is a binary protocol designed by

Macromedia to provide a lightweight, efficient means to serialize, deserialize, and

transport data between the Flash Player and the Flash Remoting gateway, as shown

in Figure 1-3.

It is not necessary to understand AMF in detail to develop robust Flash applications

that utilize Flash Remoting; however, it is useful to have a basic understanding of the

protocol. Macromedia has not documented the protocol publicly, but the HTTP

packets can be examined to gain insight into the format, which seems to be closely

based on the format used in remote shared objects (RSOs). The developers of the

AMFPHP project have partially documented the format at:

http://amfphp.org/?g=amf_format

The Flash Player communicates with the Flash Remoting gateway via the AMF pro-

tocol sent via standard HTTP requests. An AMF packet is sent as a binary

POST with

the body of the request containing the binary data serialization and remote proce-

dure call information.

Figure 1-3. Flash Player/AMF/Flash Remoting

Flash Player

Flash Remoting

Application

server

HTTP response

HTTP post

AMF

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MACROMEDIA FLASH REMOTING MX-USING FLASH REMOTING FOR FLASH MX 2004 ACTIONSCRIPT 2.0 Specifications Page 9