Programming Flash Communication Server

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Summary of Communication Components

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This Flash movie and HTML document are published and put on your web

server.

5. A Flash document (.fla file), which we’ll use to create SWF #2, is made for the

second application (application B). This document contains the managed appli-

cation monitored by the RoomList component and application A. The Flash

movie (.swf) for this document is embedded in the HTML document specified in

the Room Application Path parameter of the RoomList component as well. For

example, you can create a Flash document that uses the SimpleConnect, Chat,

and PeopleList components for a basic chat room. This document needs to pro-

cess parameters passed by the RoomList component in the URL of the HTML

document hosting the Flash movie (SWF #2). If you use the SimpleConnect

component in SWF #2 that connects to application B, the parameters will be

processed automatically. Otherwise, you’ll need to use client-side ActionScript

to process two

_root variables, username and appInstance, which are passed by

the RoomList component (

username is the string value entered by the user in the

SimpleConnect component of SWF #1, and

appInstance is the name of the

“room” instance specified in the Create Room dialog box or an existing instance

name displayed in the RoomList component).

6. Finally, the application.onConnect( ) method of the Server-Side ActionScript code

for application B must pass the

username and appInstance values to the Server-

Side ActionScript code of application A. There, an RSO used by the server-side

RoomList component stores, updates, and broadcasts the new information. In

turn, any users connected to SWF #1 will see an updated user count and new

“room” (or application instance) displayed in the UI of the client-side RoomList

component.

SetBandwidth

The SetBandwidth component allows a user to control how much bandwidth can be

used by Camera and Microphone objects utilized by other communication compo-

nents, such as the AVPresence and AudioConference components. The SetBand-

width component limits the byte throughput of a client Flash movie to a FlashCom

application. The component’s UI consists of a combo box with labels—Modem,

DSL, LAN, and Custom—as shown in Figure 2-11, indicating four connection types.

These labels are associated with preset bandwidth caps (typical connection speeds),

which can be set in the Properties panel or in client-side ActionScript.

Figure 2-11. The SetBandwidth component menu

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Chapter 2: Communication Components

Selecting Custom opens a separate window, shown in Figure 2-12, in which the user

can customize the Up and Down bandwidth limits.

Whenever a user chooses an item in the SetBandwidth component, the quality and

attributes of Camera and Microphone objects managed by other communication

components will change. As more bandwidth is allocated to the movie, the quality of

the audio/video output improves.

Nested Flash UI components

The SetBandwidth component uses three Flash MX UI components: ComboBox,

PushButton, and ScrollBar. You can alter the look of these components by changing

the appropriate skin symbol in the Component Skins folder within the Flash docu-

ment’s Library panel.

Client-side component parameters

An instance of the SetBandwidth component has six settings in the Properties panel

or Component Parameters panel, as listed in Table 2-2.

These parameters establish the preferred bandwidth limit for the incoming and out-

going connection when the user chooses the specified connection type (Modem,

DSL, or LAN) in the SetBandwidth component. The connection type also affects the

capture attributes of the Camera object (as used by the AVPresence component) and

the sampling rate of the Microphone object (as used by the AVPresence or Audio-

Conference component).

Note that:

• The practical throughput for a typical 56 Kbps dial-up modem is only 33 Kbps.

• The DSL options reflect the typical upper limit of household ADSL (asymmetric

DSL) connections. The default DSL Down value is greater than DSL Up; there-

fore, the quality of incoming streams to the Flash movie client can be more than

twice the quality of the user’s outgoing stream.

Figure 2-12. The Custom options for the SetBandwidth component