Data throttling

You specify client-to-server and server-to-client message frequency limits for a destination in the destination’s throttle-inbound and throttle-outbound elements. Use the max-frequency attribute to set the maximum number of client-to-server or server-to-client messages per second that the destination can process. Use the max-client-frequency attribute to set the maximum number of client-to-server or server-to-client messages per second that the destination can process to or from individual clients.

The following example shows throttle-outbound and throttle-inbound elements with max-frequency and max-client-frequency attributes:

... 
<destination id="MyTopic"> 
    <properties> 
        <network> 
            <throttle-outbound policy="ERROR" 
                max-frequency="100" max-client-frequency="10"/> 
            <throttle-inbound policy="IGNORE" 
                max-frequency="100" max-client-frequency="10"/> 
...

The max-frequency attribute of the throttle-outbound element indicates that the destination sends a maximum of 100 messages per second to the entire pool of Flex clients. The max-client-frequency attribute indicates that the destination sends a maximum of ten messages per second to individual Flex clients.

The max-frequency element of the throttle-inbound element indicates that the destination processes a maximum of 100 client-to-server messages per second from the entire pool of Flex clients. The max-client-frequency attribute indicates that the destination processes a maximum of ten messages per second from individual Flex clients.

The maxFrequency property of a client-side Consumer, MultiTopicConsumer, or DataService component lets you limit the number of messages the component receives from a destination. The server read this information and ensures that it limits the messages it sends to the maximum number of messages per second specified. The server sends up to the limit, but can send fewer messages depending on how many messages are available on the server to send. The maxFrequency property is set when the Consumer, MutiTopicConsumer, or DataService component subscribes.

The following example sets the maxFrequency property of a Consumer component that you create in ActionScript:

... 
<mx:Script> 
    <![CDATA[ 
        var consumer:Consumer = new Consumer(); 
        consumer.destination = "chat"; 
        consumer.maxFrequency = 40; 
        consumer.subscribe(); 
        ]]> 
</mx:Script> 
...

You can also set the maxFrequency property of a Consumer, MultiTopicConsumer, or DataService component that you create in MXML as the following example shows:

... 
<mx:Consumer id="consumer" destination="chat" maxFrequency="40"/> 
...

... 
<mx:Script> 
    <![CDATA[ 
        var consumer:MultiTopicConsumer = new MultiTopicConsumer(); 
        ... 
        consumer.maxFrequency = 40; 
        // For this subscription, use the default maxFrequency of 40. 
        consumer.addSubscription("chat.subtopic1"); 
        // Only for this subscription, overwrite the maxFrequency to 20. 
        consumer.addSubscription("chat.subtopic2", null, 20); 
        consumer.subscribe(); 
    ]]> 
</mx:Script> 
...

... 
<mx:Script> 
    <![CDATA[ 
        ... 
        var ds:DataService = new DataService("Meeting"); 
        ds.maxFrequency = 20; 
        ... 
    ]]> 
</mx:Script> 
...

... 
<mx:Script> 
    <![CDATA[ 
        ... 
        var ds:DataService = new DataService("Meeting"); 
        ds.autoSyncEnabled = false; 
        ds.manualSync.producerSubtopics.addItem("flex-room"); 
        // Set the subscription level frequency to 10. 
        ds.manualSync.consumerAddSubscription("flex-room", null, 10); 
        ds.manualSync.consumerSubscribe(); 
        ds.fill(…); 
        ... 
    ]]> 
</mx:Script> 
...

When you enable adaptive client message frequency, the server adjusts the frequency of messages sent from server to client while taking the client’s actual message processing rate into account. You specify the maximum number of messages per second that the frequency is incrementally increased or decreased.

Add something about fact that the calculations the server does are different depending the type of endpoint you are using. For example, RTMP versus long polling AMF.

To use adaptive client message frequency, you configure the adaptive-frequency property of the flex-client-outbound-queue-processor element in the flex-client section of the services-config.xml, as follows:

1. Set the flex-client-queue-processorclass value to "flex.messaging.client.AdvancedOutboundQueueProcessor".

2. Set the value of the adaptive-frequency property to true.

3. Set the value of the frequency-step-size property to the number of messages per second that you want to incrementally increase the message frequency, depending on the server’s calculation. This setting is useful when you want to gradually increase the number of messages sent per second.

   The following example shows an advanced outbound queue processor configured for adaptive message frequency:

   ... 
   <flex-client> 
       <flex-client-outbound-queue-processor 
           class="flex.messaging.client.AdvancedOutboundQueueProcessor"> 
           <properties> 
               <adaptive-frequency>true</adaptive-frequency> 
               <frequency-step-size>10</frequency-step-size> 
           </properties> 
       </flex-client-outbound-queue-processor> 
   </flex-client> 
   ...

   You can also configure an outbound queue processor for a particular endpoint in a channel definition. Such an endpoint-specific configuration overrides the global one in the services-config.xml file.