Programming Flash Communication Server

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Remoting Basics

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Remoting Basics

All of the processing and conversion of AMF is handled internally by the FlashCom

Server (or Flash Player) and the Flash Remoting gateway, so you never have to deal

with it. The NetConnection class, the base class for RTMP communications, also

serves as the foundation for Remoting. A NetConnection instance on the client pro-

vides the developer interface to create the binary data and transmit it to the destina-

tion server.

Let’s start with a simple example in which the Flash Player is the client. You could

also run this example script inside a FlashCom application if the path to the imagi-

nary service were correct. Example 11-1 shows how to use a NetConnection object to

call a remote method on an application server with the remoting gateway installed.

The first two lines should look familiar to anyone building a FlashCom connection.

In this case, the URI passed to the connect( ) method refers to the remoting gateway

that comes bundled with ColdFusion residing on the local host. Unlike an RTMP

connection, the call to connect( ) does not actually make a connection to the server,

so the call will always return

true. Internally, the client (in this case, the Flash Player)

checks the protocol used for the connection. If the protocol is

rtmp://, rtmpt://,or

rtmps://, the Flash Player immediately tries to establish a socket connection with the

remote host, and the connect( ) method returns a Boolean value indicating whether

the URI is valid. If the protocol is unspecified or is anything other than

rtmp, rtmpt,

or

rtmps, the Flash Player doesn’t try to make a connection to the remote host and

always returns

true.

The next segment of code creates a response object (also known as a responder),

named

response, with an onResult( ) method to handle the response to the remote

method call. When the server sends back a response, the Player automatically calls

the onResult( ) method of the specified object and passes the results as a single argu-

ment. Within this body of this method is where you would either process the result

or forward the result to another object for processing.

The final line uses NetConnection.call( ) to invoke the remote procedure, using the

following format:

NetConnection.call(remoteMethod, resultObject | null [, p1, ...pn])

Example 11-1. Flash Remoting with NetConnection

my_conn = new NetConnection( );

my_conn.connect("http://localhost/flashservices/gateway");

response = new Object( );

response.onResult = function (result) {

trace(result);

};

my_conn.call("services.TestService.dataEcho", response, "test message");