Program guide > Access data with client applications > Use ObjectGridManager
Access the ObjectGrid shard
WebSphere eXtreme Scale achieves high processing rates by moving the logic to where the data is and returning only results back to the client.
Application logic in a client Java™ virtual machine (JVM) needs to pull data from the server JVM that is holding the data and push it back when the transaction commits. This process slows down the rate the data can be processed. If the application logic was on the same JVM as the shard that is holding the data, then the network latency and marshalling cost is eliminated and can provide a significant performance boost.
Local reference to shard data
The ObjectGrid APIs provide a Session to the server-side method. This session is a direct reference to the data for that shard. No routing logic is on that path. The application logic can work with the data for that shard directly. The session cannot be used to access data in another partition because no routing logic exists.
A Loader plug-in also provides a way to receive an event when a shard becomes a primary partition. An application can implement a Loader and implement the ReplicaPreloadController interface. The check preload status method is only called when a shard becomes a primary. The session provided to that method is a local reference to the shards data. This approach is typically used if a partition primary needs to start some threads or subscribe to a message fabric for partition-related traffic. It might start a thread to listen for messages in a local Map using the getNextKey API.
Collocated client-server optimization
If an application uses the client APIs to access a partition that happens to be collocated with the JVM that contains the client, then the network is avoided but some marshalling still occurs because of current implementation issues. If a partitioned grid is used, then no impact on the performance of the application is made because (N-1)/N number of calls route to a different JVM. If you need local access always with a shard, then use the Loader or ObjectGrid APIs to invoke that logic.
Parent topic:Interacting with an ObjectGrid using ObjectGridManager
Controlling the life cycle of an ObjectGrid