5.3. Clustered Modes

Red Hat JBoss Data Grid offers the following clustered modes:
  • Replication Mode replicates any entry that is added across all cache instances in the cluster.
  • Invalidation Mode does not share any data, but signals remote caches to initiate the removal of invalid entries.
  • Distribution Mode stores each entry on a subset of nodes instead of on all nodes in the cluster.
The clustered modes can be further configured to use synchronous or asynchronous transport for network communications.
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5.3.1. Asynchronous and Synchronous Operations

When a clustered mode (such as invalidation, replication or distribution) is used, data is propagated to other nodes in either a synchronous or asynchronous manner.
If synchronous mode is used, the sender waits for responses from receivers before allowing the thread to continue, whereas asynchronous mode transmits data but does not wait for responses from other nodes in the cluster to continue operations.
Asynchronous mode prioritizes speed over consistency, which is ideal for use cases such as HTTP session replications with sticky sessions enabled. Such a session (or data for other use cases) is always accessed on the same cluster node, unless this node fails.
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5.3.2. About Asynchronous Communications

In Red Hat JBoss Data Grid, the local, distributed and replicated modes are represented by the local-cache, distributed-cache and replicated-cache elements respectively. Each of these elements contains a mode property, the value of which can be set to SYNC for synchronous or ASYNC for asynchronous communications.

Example 5.1. Asynchronous Communications Example Configuration

<replicated-cache name="default" 
                  start="EAGER"
                  mode="ASYNC"    
                  batching="false" 
                  statistics="true">
                 <!-- Additional configuration information here -->
</replicated-cache>

Note

This configuration is valid for both JBoss Data Grid's usage modes (Library mode and Remote Client-Server mode).
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5.3.3. Cache Mode Troubleshooting

5.3.3.1. Invalid Data in ReadExternal

If invalid data is passed to readExternal, it can be because when using Cache.putAsync(), starting serialization can cause your object to be modified, causing the datastream passed to readExternal to be corrupted. This can be resolved if access to the object is synchronized.
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5.3.3.2. Cluster Physical Address Retrieval

How can the physical addresses of the cluster be retrieved?

The physical address can be retrieved using an instance method call. For example: AdvancedCache.getRpcManager().getTransport().getPhysicalAddresses().

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