如何使用类文件设置server-to-client-heartbeat-millis的值？

Question

如何使用类文件动态设置此下面提到的xml文件的server-to-client-heartbeat-millis属性的值。

<channel-definition id="my-streaming-amf" class="mx.messaging.channels.StreamingAMFChannel"> 
        <endpoint url="http://{server.name}:{server.port}/{context.root}/messagebroker/streamingamf" 
        class="flex.messaging.endpoints.StreamingAMFEndpoint"/> 
 <properties> 
            <idle-timeout-minutes>0</idle-timeout-minutes> 
            <max-streaming-clients>10</max-streaming-clients> 
            <server-to-client-heartbeat-millis>10000</server-to-client-heartbeat-millis> 
            <user-agent-settings> 
                <user-agent match-on="MSIE" kickstart-bytes="2048" max-streaming-connections-per-session="3"/> 
                <user-agent match-on="Firefox" kickstart-bytes="2048" max-streaming-connections-per-session="3"/> 
            </user-agent-settings> 
            </properties> 
</channel-definition>

    </channels>

提前致谢。