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Remote Shared Objects |
  
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Remote Shared Objects |
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Remote Shared Object (RSO) is a WebORB feature natively supported by all RTMP clients (Flex, AIR, Flash). An RSO is a specialized data dictionary containing a set of keys with corresponding values. An RSO has a name used by the clients to connect to it. When more than one client connects to the same RSO and makes a change by adding, removing or modifying a key/value pair, all other clients receive an update from the server notifying them about the change. In the context of a single server, WebORB maintains the RTMP connections with all the clients and, as a result, can easily notify the clients about the changes in the RSO. In a clustered environment, the clients no longer need to connect to the same WebORB instance in order to operate on an RSO. A WebORB cluster shares the state of a remote shared object and thus when a client makes a change in an RSO, all other clients receive an update even if they are not connected to the same server as the original client. Consider the following scenario:
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A cluster consists of two servers running the WebORB RTMP server. There are two RTMP clients: A and B. The servers are identically configured and each has an instance of a remote shared object. |
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Client A connects to the remote shared object hosted on WebORB Node 1 and retrieves its contents. Client B connects to the RSO on WebORB Node 2 and also gets its contents. |
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Client A updates a property in its copy of the RSO. The update is sent to WebORB Node 1. |
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WebORB Node 1 is aware of the clustered environment it runs in and synchronizes the change with the other server in the cluster. WebORB Node 2 receives the update, modifies the remote shared object hosted in that server and delivers the synchronization event to client B connected to the server. |
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Configuration
A special configuration is required to enable clustering of Remote Shared Objects. An messaging application requiring support for clustered RSOs, must contain the following configuration in the application's configuration file - app.xml:
<sharedObjectService>Weborb.Cluster.SharedObject.ClusterSharedObjectService</sharedObjectService>
The minimal configuration file for a message application with cluster-enabled Remote Shared Objects should look as shown below:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<extensibility>
<sharedObjectService>Weborb.Cluster.SharedObject.ClusterSharedObjectService</sharedObjectService>
</extensibility>
</configuration>
