External coherence update#
Specifies the amount of time from last update that entries will be kept by the cache before being expired. Legal values are positive integers or zero. The scheme's class-name element may be used to provide custom extensions to SerializationCache, which implement alternative eviction policies. Once this limit is exceeded, the cache will begin the pruning process, evicting the least recently used entries until the number of units is brought below this limit. Contains the maximum number of units that can be placed in the cache before pruning occurs. Specifies an implementation of a which will be notified of events occurring on the cache. Specifies initialization parameters, for use in custom external cache implementations which implement the .XmlConfigurable interface. .SimpleSerializationMap - for unlimited size cachesĪnd declare the exact same set of public constructors as the superclass.Specifies a custom implementation of the external cache.Īny custom implementation must extend one of the following classes: Specifies the name of another scheme to inherit The name must be unique within a configuration file. The following table describes the elements you can define within the external-scheme element. Clustered persistence should be configured via a read-write-backing-map-scheme Persistence (long-term storage)Įxternal caches are generally used for temporary storage of large data sets,įor example as the back-tier of an overflow-scheme.Ĭertain implementations do however support persistence for non-clustered caches,įor details. The cache may be configured as size-limited, which means that once it reaches its maximum allowable size it prunes itself.Įviction against disk based caches can be expensive, consider usingĮxternal schemes support automatic expiration of entries based on the age of the value, as configured by the expiry-delay. For the purpose of this note, consistency.
Context 'Consistency' in law is, normally understood as the absence of contradictions 'coherence', on the other hand, refers to the way in which the substance of different policies/actions forms part of a coherent whole1. uses NIO to implement an off JVM heap, in-memory cache Session two: Internal/external coherence on Human Rights Background note 1. uses NIO to implement memory-mapped file based cache uses a Coherence LH on-disk database cache uses Berkeley Database JE to implement an on-disk cache allows definition of custom implementations of store managers a wrapper providing asynchronous write capabilities for of other store manager The main sub-division of the coherence criterion within the OECD/DAC criteria is between internal and external coherence. if the high-units element is specified and not zero then SerializationCache is used Įxternal schemes use a pluggable store manager to store and retrieve binary key value pairs.The implementation type is chosen based on the following rule: .SerializationCache - for size limited caches..SerializationMap - for unlimited size caches.Coherence 3.3 User Guide : external-scheme external-scheme external-schemeĮxternal schemes define caches which are not JVM heap based, allowing for greaterĬache samples for examples of various external cache configurations.
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