6.10.5 Cache entry IDs
To cache an object, the application server must know how to generate a unique ID for different invocations of that object. These IDs are built either from user-written custom Java code or from rules that are defined in the cache policy of each cache entry. (Note that custom Java code needs to be placed into a shared library.)
Each cache entry can have multiple cache ID rules that run in order until either a rule returns a non-empty cache ID, or no more rules are left to run. If none of the cache ID generation rules produce a valid cache ID, the object is not cached.
Each cache-id element defines a rule for caching an object and is composed of the following sub-elements:
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| Component |
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| Timeout |
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| Inactivity |
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| Priority |
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| Property |
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| Idgenerator |
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| Metadatagenerator |
Example | -21 illustrates a cache-id element.
Example 6-21 cache-id definition grammar
<cache-id>
component* | timeout? | inactivity? | priority? | property* | idgenerator? | metadatagenerator?
</cache-id>
In this example, * = zero or more, | = or, and ? = value.