Used in: caching-schemes, near-scheme, versioned-near-scheme, overflow-scheme
The optimistic scheme defines a cache which fully replicates all of its data to all cluster nodes that are running the service. See the services overview for a more detailed description of optimistic caches.
Unlike the replicated and partitioned caches, optimistic caches do not support concurrency control (locking). Individual operations against entries are atomic but there is no guarantee that the value stored in the cache does not change between atomic operations. The lack of concurrency control allows optimistic caches to support very fast write operations.
Storage for the cache is specified via the backing-map-scheme. For instance an optimistic cache which uses a local cache for its backing map will result in cache entries being stored in-memory.
The following table describes the elements you can define within the optimistic-scheme element.
| Element | Required/Optional | Description |
|---|---|---|
| <scheme-name> | Optional | Specifies the scheme's name. The name must be unique within a configuration file. |
| <scheme-ref> | Optional | Specifies the name of another scheme to inherit from. |
| <service-name> | Optional | Specifies the name of the service which will manage caches created from this scheme.
services are configured from within the operational descriptor. |
| <listener> | Optional | Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache. |
| <backing-map-scheme> | Optional | Specifies what type of cache will be used within the cache server to store the entries.
Legal values are: In order to ensure cache coherence, the backing-map of an optimistic cache must not use a read-through pattern to load cache entries. Either use a cache-aside pattern from outside the cache service, or switch to the distributed-scheme, which supports read-through clustered caching. |
| <autostart> | Optional | The autostart element is intended to be used by cache servers (i.e. com.tangosol.net.DefaultCacheServer). It specifies whether or not the cache services associated with this cache scheme should be automatically started at a cluster node.
Legal values are true or false. Default value is false. |