Programming Flash Communication Server

This is the Title of the Book, eMatter Edition

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

Making a Connection

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79

instance to which to connect, followed by any number of optional parameters. In

this example, a username and password are supplied after the URI. The connect( )

method returns

false if it detects a malformed URI; otherwise, it returns true, and

Flash attempts to connect to the server.

Not all malformed URIs are caught by the connect( ) method. You

must always make sure the protocol is either

rtmp or rtmpt followed by

a colon; otherwise, the connect( ) method may return

true and then

fail.

The URI can be an absolute URI that includes a hostname or a relative URI that does

not. After the connect( ) method is called, the URI passed into it is available as the

uri property of the NetConnection object.

Absolute URIs

An absolute URI is a string that includes protocol, host, optional port, application

name, and optional instance name segments. The format of an absolute URI is:

rtmp[t]://host[:port]/applicationName[/instanceName]

The parts of the URI in square brackets are optional. An absolute URI contains all

the information needed to identify an application instance to which to connect. The

following sections describe all the parts of an absolute URI.

Protocol

The first part of an absolute URI is the protocol or scheme and must always be speci-

fied as

rtmp, rtmpt,orrtmps, followed by :// for an absolute URI or :/ for a relative

URI. RTMP is preferred because it is the native protocol for FlashCom communica-

tions. Adding the optional t in

rtmpt indicates that HTTP tunneling is to be used.

Tunneling is less efficient, because RTMP messages must be wrapped in HTTP head-

ers, and the server must be constantly polled by the Flash movie. However, tunnel-

ing may successfully make connections through firewalls and proxy servers when

RTMP access fails. Tunneling was first added to Flash Player 6.0.65.0 and Flash-

Com 1.5. When run in a browser, the Flash Player uses the browser to make the

HTTP connections to the server that RTMPT relies on. Since the browser normally

also supports SSL, Macromedia added the ability to use the SSL by specifying the

rtmps protocol instead of rtmpt. When RTMPS is used, the Flash Player attempts to

establish a tunneling connection over HTTPS to FlashCom. Even though FlashCom

1.5 does not support SSL, it is possible to take advantage of RTMPS using additional

server software or specialized network hardware in order to have completely

encrypted real-time communications between Flash movies and FlashCom. Config-

uring a system to accept SSL connections is briefly discussed in Chapter 18 and at:

http://www.macromedia.com/devnet/mx/flashcom/articles/firewalls_proxy04.html