flex.messaging.services.messaging.adapters
Class MessagingAdapter

java.lang.Object
  flex.management.ManageableComponent
      flex.messaging.services.ServiceAdapter
          flex.messaging.services.messaging.adapters.MessagingAdapter

All Implemented Interfaces:

Manageable, FlexComponent, FlexConfigurable, MessagingSecurity

Direct Known Subclasses:

ActionScriptAdapter

public abstract class MessagingAdapter
extends ServiceAdapter
implements MessagingSecurity

Base adapter class for publish/subscribe messaging adapters. You extend this class if you want to implement your own messaging adapter. A custom messaging adapter has the ability to implement authorization logic for specific subtopics, and may also control how messages are routed. A more advanced messaging adapter can take control over the subscription process and have complete control over the subscription process for producers and consumers.

All messaging adapters must provide an implementation for the invoke method. A simple invoke implementation which would give you similar functionality as the ActionScriptAdapter is simply: public Object invoke(Message message) { MessageService msgService = (MessageService)service; msgService.pushMessageToClients(message, true); msgService.sendPushMessageFromPeer(message, true); return null; } This method is called for each data message sent from the client. It gets a reference to the MessageService which is controlling delivery of messages for this adapter. It uses the pushMessageToClients method to send the message to all clients connected to this server. It then uses the sendPushMessageFromPeer method to send the message to other servers which will then route the message to each client connected to those servers. In both cases, we pass the "evalSelector" parameter as true. This indicates that the message service will only send the message to those clients whose selector pattern evaluates to true for the supplied message. If you supply false, the selector pattern is ignored and the message is delivered to the clients even if the pattern evaluates to false.

The default behavior is for the messaging adapter to use the builtin FDS subscription mechanism. The client sends subscribe and unsubscribe command messages which are managed by the MessageService, not the adapter. If you override the "handlesSubscriptions" method to return true, your adapter's manage method is called for each of these command messages instead. You must then override this method to provide an implementation for these operations. See the docs on the CommandMessage class for details on the message format.

See Also:

flex.messaging.ServiceAdapter, MessageService, Message, CommandMessage

Field Summary

Fields inherited from class flex.messaging.services.ServiceAdapter

LOG_CATEGORY

Constructor Summary

MessagingAdapter()

Method Summary

boolean	allowSend(Subtopic subtopic) This method is invoked before a client message is sent to a subtopic, so that custom application logic can determine whether the client should be allowed to send to the specified subtopic.
boolean	allowSubscribe(Subtopic subtopic) This method is invoked before a client subscribe request is processed, so that custom application logic can determine whether the client should be allowed to subscribe to the specified subtopic.

Methods inherited from class flex.messaging.services.ServiceAdapter

getAdapterState, getDestination, handlesSubscriptions, invoke, manage, setAdapterState, setDestination, start, stop

Methods inherited from class flex.management.ManageableComponent

getControl, getId, getParent, initialize, isManaged, isStarted, isValid, setControl, setId, setManaged, setParent

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MessagingAdapter

public MessagingAdapter()

Method Detail

allowSubscribe

public boolean allowSubscribe(Subtopic subtopic)

This method is invoked before a client subscribe request is processed, so that custom application logic can determine whether the client should be allowed to subscribe to the specified subtopic. You can access the current user via FlexContext.getUserPrincipal().

Specified by:

allowSubscribe in interface MessagingSecurity

Parameters:

subtopic - The subtopic the client is attempting to subscribe to.

Returns:

true to allow the subscription, false to prevent it.

allowSend

public boolean allowSend(Subtopic subtopic)

This method is invoked before a client message is sent to a subtopic, so that custom application logic can determine whether the client should be allowed to send to the specified subtopic. You can access the current user via FlexContext.getUserPrincipal().

Specified by:

allowSend in interface MessagingSecurity

Parameters:

subtopic - The subtopic the client is attempting to send a message to.

Returns:

true to allow the message to be sent, false to prevent it.