Programming Flash Communication Server

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Chapter 2: Communication Components

Nested Flash UI components

The AudioConference component uses four Flash MX UI components: CheckBox,

ListBox, PushButton, and ScrollBar.

Component process overview

When the AudioConference component loads into a Flash movie, the component

uses an existing NetConnection object (which can be provided by a SimpleConnect

component) to create or connect to a non-persistent RSO named

FCAudioConference.

audio

.

Whenever a communication component instance uses an RSO, any

changes made to the RSO are broadcast to all connected users (or par-

ticipants) of the same application instance. The communication com-

ponents do not prohibit or exclude users of the same application

instance from sharing data with one another.

This RSO keeps track of each connected user. When a user clicks the Talk button,

the component attaches his microphone output to a NetStream instance and sets a

property within the RSO to

true. This property’s name is based on the user’s ID,

which is provided by the server-side component framework. When other clients

receive this updated value in the SharedObject.onSync( ) handler, the audio stream

from the other user is played. When the user releases the Talk button, the compo-

nent sets the RSO’s property to

false, and the user’s microphone output detaches

from the stream.

AVPresence

The AVPresence component, by far one of the more popular communication compo-

nents, allows a user connected to a FlashCom application to send an audio and/or

video stream to other users. An AVPresence instance presents a masked area of the

user’s camera output as shown in Figure 2-3. The user can selectively mute the audio

and/or video output. The component displays the microphone’s activity level along

the right border.

Figure 2-2. The AudioConference component

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Summary of Communication Components

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One of the special attributes of the AVPresence component is that it can be used to

either send a user’s audio/video stream or receive another user’s audio/video stream.

The AVPresence instance name establishes a unique identifier within the FlashCom

application. If you place an AVPresence component instance named

user_1_mc

within a Flash movie (a .swf file), anyone who loads the Flash movie and connects to

the FlashCom application can engage the

user_1_mc instance to begin streaming

audio/video. Once a user has started to publish a stream with the

user_1_mc instance,

any other users who have loaded the same Flash movie will start to see that user’s

stream in their instance of

user_1_mc. If you want to provide multiple users simulta-

neous access to the functionality of the AVPresence component, you will need to cre-

ate a unique instance of the AVPresence component for each user.

Once a user relinquishes control of an AVPresence instance, another user can use

that same instance to start publishing her audio/video stream.

In order for a user to gain access to the AVPresence component, the following events

must occur:

1. The AVPresence component must be connected to the active NetConnection

instance of the FlashCom application. This connection can be created with the

SimpleConnect component (discussed later in this chapter) or with custom

ActionScript.

2. The user must specify a preferred login name in the SimpleConnect component,

or AVPresence.setUsername( ) must be invoked with a string value. If a user’s

name is not set, the AVPresence instance displays the text “Login to Send Audio/

Video.”

3. Once a username has been established, the user can click the Send Audio/Video

link within the AVPresence instance to begin publishing an audio/video stream

to the FlashCom application. Any other user viewing the same AVPresence

instance will receive the streaming audio and video.

4. To stop sending an audio/video stream, the user must roll over the instance’s

video area and click the button depicting a red X in a circle, in the lower-left cor-

ner of the component as seen in Figure 2-3. Once the stream stops publishing,

another user can begin using the same AVPresence instance.

Figure 2-3. The AVPresence component