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Oracle® Coherence Developer's Guide
Release 3.5

Part Number E14509-01
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D Cache Configuration Elements

This appendix provides a listing of the elements that can be used in a cache configuration. In addition, it describes the deployment descriptor file in which they appear.

Cache Configuration Deployment Descriptor

Use the cache configuration deployment descriptor to specify the various types of caches which can be used within a cluster. For information on configuring cluster communication and services see Appendix H, "Operational Configuration Elements."

Document Location

The name and location of the descriptor is specified in the operational deployment descriptor and defaults to coherence-cache-config.xml. The default configuration descriptor (packaged in coherence.jar) will be used unless a custom one is found within the application's classpath. It is recommended that all nodes within a cluster use identical cache configuration descriptors.

Document Root

The root element of the configuration descriptor is <cache-config>. This is where you may begin configuring your caches.

Document Format

The Cache Configuration descriptor should begin with the following DOCTYPE declaration:

<!DOCTYPE cache-config SYSTEM "cache-config.dtd">

Note:

When deploying Coherence into environments where the default character set is EBCDIC rather than ASCII, make sure that this descriptor file is in ASCII format and is deployed into its runtime environment in the binary format.

Command Line Override

Oracle Coherence provides a powerful command line override feature which allows any element defined in this descriptor to be overridden from the Java command line if it has a system-property attribute defined in the descriptor. For more information on this feature, see Appendix L, "Command Line Overrides".

Examples

See Appendix F, "Sample Cache Configurations" for usage examples.


Element Index

The following table lists all non-terminal elements which may be used from within a cache configuration.

Table D-1 Cache Configuration Elements

Element Used In:

acceptor-config

proxy-scheme

async-store-manager

external-scheme, paged-external-scheme

authorized-hosts

tcp-acceptor

backing-map-scheme

distributed-scheme, optimistic-scheme, replicated-scheme

backup-storage

distributed-scheme

bdb-store-manager

external-scheme, paged-external-scheme, async-store-manager

cache-config

root element

cache-mapping

caching-scheme-mapping

cache-service-proxy

proxy-config

caching-scheme-mapping

cache-config

caching-schemes

cache-config

class-scheme

caching-schemes, local-scheme, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, overflow-scheme, read-write-backing-map-scheme, cachestore-scheme, listener

cachestore-scheme

local-scheme, read-write-backing-map-scheme

custom-store-manager

external-scheme, paged-external-scheme, async-store-manager

disk-scheme

caching-schemes

distributed-scheme

caching-schemes, near-scheme, overflow-scheme

external-scheme

caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, overflow-scheme, read-write-backing-map-scheme

init-param

init-params

init-params

class-scheme

initiator-config

remote-cache-scheme, remote-invocation-scheme

invocation-scheme

caching-schemes

jms-acceptor

acceptor-config

jms-initiator

initiator-config

key-associator

distributed-scheme

key-partitioning

distributed-scheme

lh-file-manager

external-scheme, paged-external-scheme, async-store-manager

listener

disk-scheme, local-scheme, external-scheme, paged-external-scheme, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, overflow-scheme, read-write-backing-map-scheme

local-scheme

caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, overflow-scheme, read-write-backing-map-scheme

near-scheme

caching-schemes

nio-file-manager

external-scheme, paged-external-scheme, async-store-manager

nio-memory-manager

external-scheme, paged-external-scheme, async-store-manager

operation-bundling

cachestore-scheme, distributed-scheme, remote-cache-scheme

optimistic-scheme

caching-schemes, near-scheme, overflow-scheme

outgoing-message-handler

acceptor-config, initiator-config

overflow-scheme

caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme, read-write-backing-map-scheme

paged-external-scheme

caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, overflow-scheme, read-write-backing-map-scheme

partitioned

backing-map-scheme

proxy-config

proxy-scheme

proxy-scheme

caching-schemes

read-write-backing-map-scheme

caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme

remote-cache-scheme

cachestore-scheme, caching-schemes, near-scheme

remote-invocation-scheme

caching-schemes

replicated-scheme

caching-schemes, near-scheme, overflow-scheme

tcp-acceptor

acceptor-config

tcp-initiator

initiator-config



acceptor-config

Used in: proxy-scheme

Description

The acceptor-config element specifies the configuration information for a protocol-specific connection acceptor. The connection acceptor is used by a proxy service to enable Coherence*Extend clients to connect to the cluster and use the services offered by the cluster without having to join the cluster.

The acceptor-config element must contain exactly one protocol-specific connection acceptor configuration element (either jms-acceptor or tcp-acceptor).

Elements

Table D-2 describes the elements you can define within the acceptor-config element.

Table D-2 acceptor-config Subelements

Element Required/Optional Description

<connection-limit>

Optional

The maximum number of simultaneous connections allowed by this connection acceptor. Valid values are positive integers and zero. A value of zero implies no limit. Default value is zero.

<jms-acceptor>

Optional

Specifies the configuration info for a connection acceptor that enables Coherence*Extend clients to connect to the cluster over JMS.

<outgoing-message-handler>

Optional

Specifies the configuration info used by the connection acceptor to detect dropped client-to-cluster connections.

<serializer>

Optional

Specifies the class configuration info for a com.tangosol.io.Serializer implementation used by the connection acceptor to serialize and deserialize user types. For example, the following configures a ConfigurablePofContext that uses the my-pof-types.xml POF type configuration file to deserialize user types to and from a POF stream:

<serializer>
  <class-name>com.tangosol.io.pof.ConfigurablePofContext</class-name>
  <init-params>
    <init-param>
      <param-type>string</param-type>
      <param-value>my-pof-types.xml</param-value>
    </init-param>
  </init-params>
</serializer>

<tcp-acceptor>

Optional

Specifies the configuration info for a connection acceptor that enables Coherence*Extend clients to connect to the cluster over TCP/IP.

<use-filters>

Optional

Contains the list of <filters> names to be used by this connection acceptor.For example, specifying use-filter as follows will activate gzip compression for all network messages, which can help substantially with WAN and low-bandwidth networks.

<use-filters>
    <filter-name>gzip</filter-name>
</use-filters>


address-provider

Used in: tcp-initiator

Description

Contains the configuration info for an address factory that implements the com.tangosol.net.AddressProvider interface.

Elements

Table D-3 describes the subelements you can define within the address-provider element.

Table D-3 address-provider Subelements

Element Required/Optional Description

<class-factory-name>

Optional

Specifies a fully specified name of a Java class that will be used as a factory for object instantiation.

<class-name>

Required

The name of a class that implements the com.tangosol.net.AddressProvider interface.

<init-params>

Optional

Specifies initialization parameters which are accessible by implementations which support the com.tangosol.run.xml.XmlConfigurable interface, or which include a public constructor with a matching signature.

<method-name>

Optional

Specifies the name of a static factory method on the factory class which will perform object instantiation.



async-store-manager

Used in: external-scheme, paged-external-scheme.

Description

The async-store-manager element adds asynchronous write capabilities to other store manager implementations. Supported store managers include:

Implementation

This store manager is implemented by the com.tangosol.io.AsyncBinaryStoreManager class.

Elements

Table D-4 describes the subelements you can define within the async-store-manager element.

Table D-4 async-store-manager Subelements

Element Required/Optional Description

<async-limit>

Optional

Specifies the maximum number of bytes that will be queued to be written asynchronously. Setting the value to zero does not disable the asynchronous writes; instead, it indicates that the implementation default for the maximum number of bytes are necessary.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K (kilo, 210)

  • M (mega, 220)

If the value does not contain a factor, a factor of one is assumed. Valid values are any positive memory sizes and zero. Default value is 4MB.

<bdb-store-manager>

Optional

Configures the external cache to use Berkeley Database JE on disk databases for cache storage.

<class-name>

Optional

Specifies a custom implementation of the async-store-manager. Any custom implementation must extend the com.tangosol.io.AsyncBinaryStoreManager class and declare the exact same set of public constructors.

<custom-store-manager>

Optional

Configures the external cache to use a custom storage manager implementation.

<init-params>

Optional

Specifies initialization parameters, for use in custom async-store-manager implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<lh-file-manager>

Optional

Configures the external cache to use a Coherence LH on disk database for cache storage.

<nio-file-manager>

Optional

Configures the external cache to use a memory-mapped file for cache storage.

<nio-memory-manager>

Optional

Configures the external cache to use an off JVM heap, memory region for cache storage.



backing-map-scheme

Used in: distributed-scheme, optimistic-scheme, replicated-scheme

Description

Specifies what type of cache will be used within the cache server to store the entries.

When using an overflow-based backing map it is important that the corresponding backup-storage be configured for overflow (potentially using the same scheme as the backing-map). See "Partitioned Cache with Overflow" for an example configuration.

Note:

The partitioned subelement is used if and only if the parent element is the distributed-scheme.

Elements

Table D-5 describes the subelements you can define within the backing-map-scheme element. :

Table D-5 backing-map-scheme Subelements

Element Required/Optional Description

<class-scheme>

Optional

Class schemes provide a mechanism for instantiating an arbitrary Java object for use by other schemes. The scheme which contains this element will dictate what class or interface(s) must be extended.

<external-scheme>

Optional

External schemes define caches which are not JVM heap based, allowing for greater storage capacity.

<local-scheme>

Optional

Local cache schemes define in-memory "local" caches. Local caches are generally nested within other cache schemes, for instance as the front-tier of a near scheme.

<paged-external-scheme>

Optional

As with external-scheme, paged-external-schemes define caches which are not JVM heap based, allowing for greater storage capacity.

<partitioned>

Optional

 

<overflow-scheme>

Optional

The overflow-scheme defines a two-tier cache consisting of a fast, size limited front-tier, and slower but much higher capacity back-tier cache.

<read-write-backing-map-scheme

Optional

The read-write-backing-map-scheme defines a backing map which provides a size limited cache of a persistent store.

<versioned-backing-map-scheme>

Optional

The versioned-backing-map-scheme is an extension of a read-write-backing-map-scheme, defining a size limited cache of a persistent store. It uses object versioning to determine what updates need to be written to the persistent store.



backup-storage

Used in: distributed-scheme.

Description

The backup-storage element specifies the type and configuration of backup storage for a partitioned cache.

Elements

The following table describes the elements you can define within the backup-storage element.

Table D-6 backup-storage Subelements

Element Required/Optional Description

<class-name>

Optional

Only applicable with the custom type. Specifies a class name for the custom storage implementation. If the class implements com.tangosol.run.xml.XmlConfigurable interface then upon construction, the setConfig method is called passing the entire backup-storage element. Default value is the backup-storage/class-name value specified in the tangosol-coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.

<directory>

Optional

Only applicable with the file-mapped type. Specifies the path name for the directory that the disk persistence manager (com.tangosol.util.nio.MappedBufferManager) will use as "root" to store files in. If not specified or specifies a non-existent directory, a temporary file in the default location is used. Default value is the backup-storage/directory value specified in the tangosol-coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.

<initial-size>

Optional

Only applicable with the off-heap and file-mapped types.Specifies the initial buffer size in bytes.The value of this element must be in the following format:

[\d]+[[.][\d]]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of mega is assumed. Legal values are positive integers between 1 and Integer.MAX_VALUE - 1023 (that is, 2,147,482,624 bytes). Default value is the backup-storage/initial-size value specified in the tangosol-coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.

<maximum-size>

Optional

Only applicable with the off-heap and file-mapped types. Specifies the initial buffer size in bytes.The value of this element must be in the following format:

[\d]+[[.][\d]]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of mega is assumed. Legal values are positive integers between 1 and Integer.MAX_VALUE - 1023 (that is, 2,147,482,624 bytes). Default value is the backup-storage/maximum-size value specified in the tangosol-coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.

<scheme-name>

Optional

Only applicable with the scheme type. Specifies a scheme name for the ConfigurableCacheFactory. Default value is the backup-storage/scheme-name value specified in the tangosol-coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.

<type>

Required

Specifies the type of the storage used to hold the backup data. Legal values are:

Default value is the value specified in the tangosol-coherence.xml descriptor. For more information, see the <backup-storage/type> parameter in "DistributedCache Service Parameters".



bdb-store-manager

Used in: external-scheme, paged-external-scheme, async-store-manager.

Note:

Berkeley Database JE Java class libraries are required to use a bdb-store-manager, see the Berkeley Database JE product page for additional information.

Description

The BDB store manager is used to define external caches which will use Berkeley Database JE on disk embedded databases for storage. See the examples of Berkeley-based store configurations in "Persistent Cache on Disk" and "In-memory Cache with Disk Based Overflow".

Implementation

This store manager is implemented by the com.tangosol.io.bdb.BerkeleyDBBinaryStoreManager class, and produces BinaryStore objects implemented by the com.tangosol.io.bdb.BerkeleyDBBinaryStore class.

Elements

Table D-7 describes the elements you can define within the bdb-store-manager element.

Table D-7 bdb-store-manager Subelements

Element Required/Optional Description

<class-name>

Optional

Specifies a custom implementation of the Berkeley Database BinaryStoreManager. Any custom implementation must extend the com.tangosol.io.bdb.BerkeleyDBBinaryStoreManager class and declare the exact same set of public constructors.

<directory>

Optional

Specifies the path name to the root directory where the Berkeley Database JE store manager will store files. If not specified or specified with a non-existent directory, a temporary directory in the default location will be used.

<init-params>

Optional

Specifies additional Berkeley DB configuration settings. See Berkeley DB Configuration. Also used to specify initialization parameters, for use in custom implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<store-name>

Optional

Specifies the name for a database table that the Berkeley Database JE store manager will use to store data in. Specifying this parameter will cause the bdb-store-manager to use non-temporary (persistent) database instances. This is intended only for local caches that are backed by a cache loader from a non-temporary store, so that the local cache can be pre-populated from the disk on startup. When specified, it is recommended that it use the {cache-name} macro. Normally this parameter should be left unspecified, indicating that temporary storage is to be used. See Appendix E, "Cache Configuration Parameter Macros" for more information on the {cache-name} macro.



bundle-config

Used in: operation-bundling.

Description

The bundle-config element specifies the bundling strategy configuration for one or more bundle-able operations.

Elements

Table D-8 describes the subelements you can define within the bundle-config element.

Table D-8 bundle-config Subelements

Element Required/Optional Description

<auto-adjust>

Optional

Specifies whether the auto adjustment of the preferred-size value (based on the run-time statistics) is allowed.

Valid values are true or false. Default value is false.

<delay-millis>

Optional

Specifies the maximum amount of time in milliseconds that individual execution requests are allowed to be deferred for a purpose of "bundling" them together and passing into a corresponding bulk operation. If the preferred-size threshold is reached before the specified delay, the bundle is processed immediately.

Valid values are positive numbers. Default value is 1.

<operation-name>

Required

Specifies the operation name for which calls performed concurrently on multiple threads will be "bundled" into a functionally analogous "bulk" operation that takes a collection of arguments instead of a single one.

Valid values depend on the bundle configuration context. For the <cachestore-scheme> the valid operations are:

  • load"

  • store

  • erase

For the <distributed-scheme> and <remote-cache-scheme> the valid operations are:

  • get

  • put

  • remove

In all cases there is a pseudo operation named all, referring to all valid operations. Default value is all.

<preferred-size>

Optional

Specifies the bundle size threshold. When a bundle size reaches this value, the corresponding "bulk" operation will be invoked immediately. This value is measured in context-specific units.

Valid values are zero (disabled bundling) or positive values. Default value is zero.

<thread-threshold>

Optional

Specifies the minimum number of threads that must be concurrently executing individual (non-bundled) requests for the bundler to switch from a pass-through to a bundling mode.

Valid values are positive numbers. Default value is 4.



cache-config

Root Element

Description

The cache-config element is the root element of the cache configuration descriptor, coherence-cache-config.xml. For more information on this document, see "Cache Configuration Deployment Descriptor".

At a high level, a cache configuration consists of cache schemes and cache scheme mappings. Cache schemes describe a type of cache, for instance a database backed, distributed cache. Cache mappings define what scheme to use for a given cache name.

Elements

Table D-9 describes the subelements you can define within the cache-config element.

Table D-9 cache-config Subelements

Element Required/Optional Description

<caching-scheme-mapping>

Required

Specifies the caching-scheme that will be used for caches, based on the cache's name.

<caching-schemes>

Required

Defines the available caching-schemes for use in the cluster.



cache-mapping

Used in: caching-scheme-mapping

Description

Each cache-mapping element specifies the caching-schemes which are to be used for a given cache name or pattern.

Elements

Table D-10 describes the subelements you can define within the cache-mapping element.

Table D-10 cache-mapping Subelements

Element Required/Optional Description

<cache-name>

Required

Specifies a cache name or name pattern. The name is unique within a cache factory.The following cache name patterns are supported:

  • exact match, for example, MyCache

  • prefix match, for example, My* that matches to any cache name starting with My

  • any match "*", that matches to any cache name

The patterns get matched in the order of specificity (more specific definition is selected whenever possible). For example, if both MyCache and My* mappings are specified, the scheme from the MyCache mapping will be used to configure a cache named MyCache.

<scheme-name>

Required

Contains the caching scheme name. The name is unique within a configuration file. Caching schemes are configured in the caching-schemes element.

<init-params>

Optional

Allows specifying replaceable cache scheme parameters. During cache scheme parsing, any occurrence of any replaceable parameter in format param-name is replaced with the corresponding parameter value. Consider the following cache mapping example:

<cache-mapping>
  <cache-name>My*</cache-name>
  <scheme-name>my-scheme</scheme-name>
  <init-params>
    <init-param>
      <param-name>cache-loader</param-name>
      <param-value>com.acme.MyCacheLoader</param-value>
    </init-param>
    <init-param>
      <param-name>size-limit</param-name>
      <param-value>1000</param-value>
    </init-param>
  </init-params>
</cache-mapping>

For any cache name match My*, any occurrence of the literal cache-loader in any part of the corresponding cache-scheme element will be replaced with the string com.acme.MyCacheLoader and any occurrence of the literal size-limit will be replaced with the value of 1000. Since Coherence 3.0



cache-service-proxy

Used in: proxy-config

Description

The cache-service-proxy element contains the configuration info for a cache service proxy managed by a proxy service.

Elements

Table D-11 describes the elements you can define within the cache-service-proxy element.

Table D-11 cache-service-proxy Subelements

Element Required/Optional Description

<enabled>

Optional

Specifies whether the cache service proxy is enabled. If disabled, clients will not be able to access any proxied caches. Legal values are true or false. Default value is true.

<lock-enabled>

Optional

Specifies whether lock requests from remote clients are permitted on a proxied cache. Legal values are true or false. Default value is false.

<read-only>

Optional

Specifies whether requests from remote clients that update a cache are prohibited on a proxied cache. Legal values are true or false. Default value is false.



cachestore-scheme

Used in: local-scheme, read-write-backing-map-scheme, versioned-backing-map-scheme.

Description

Cache store schemes define a mechanism for connecting a cache to a back-end data store. The cache store scheme may use any class implementing either the com.tangosol.net.cache.CacheStore or com.tangosol.net.cache.CacheLoader interfaces, where the former offers read-write capabilities, where the latter is read-only. Custom implementations of these interfaces may be produced to connect Coherence to various data stores. See "Cache of a Database" for an example of using a cachestore-scheme.

Elements

Table D-12 describes the elements you can define within the cachestore-scheme element.

Table D-12 cachestore-scheme Subelements

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. See "Scheme Inheritance".

<class-scheme>

Optional

Specifies the implementation of the cache store. The specified class must implement one of the following two interfaces.

<remote-cache-scheme>

Optional

Configures the cachestore-scheme to use Coherence*Extend as its cache store implementation.

<operation-bundling>

Optional

Specifies the configuration info for a bundling strategy.



caching-scheme-mapping

Used in: cache-config

Description

Defines mappings between cache names, or name patterns, and caching-schemes. For instance you may define that caches whose names start with accounts- will use a distributed (distributed-scheme) caching scheme, while caches starting with the name rates- will use a replicated-scheme caching scheme.

Elements

Table D-13 describes the subelement you can define within the caching-scheme-mapping element.

Table D-13 caching-scheme-mapping Subelement

Element Required/Optional Description

<cache-mapping>

Optional

Contains a single binding between a cache name and the caching scheme this cache will use.



caching-schemes

Used in: cache-config

Description

The caching-schemes element defines a series of cache scheme elements. Each cache scheme defines a type of cache, for instance a database backed partitioned cache, or a local cache with an LRU eviction policy. Scheme types are bound to actual caches using caching-scheme-mappings.

Scheme Types and Names

Each of the cache scheme element types is used to describe a different type of cache, for instance distributed, versus replicated. Multiple instances of the same type may be defined so long as each has a unique scheme-name.

Example D-1 illustrates the configuration of two different distributed schemes

Example D-1 Configuring Two Different Distributed Schemes

<distributed-scheme>
  <scheme-name>DistributedInMemoryCache</scheme-name>
  <service-name>DistributedCache</service-name>
  <backing-map-scheme>
    <local-scheme/>
  </backing-map-scheme>
</distributed-scheme>

<distributed-scheme>
  <scheme-name>DistributedOnDiskCache</scheme-name>
  <service-name>DistributedCache</service-name>
  <backing-map-scheme>
    <external-scheme>
      <nio-file-manager>
        <initial-size>8MB</initial-size>
        <maximum-size>512MB</maximum-size>
        <directory></directory>
      </nio-file-manager>
    </external-scheme>
  </backing-map-scheme>
</distributed-scheme>

Nested Schemes

Some caching scheme types contain nested scheme definitions. For instance in the above example the distributed schemes include a nested scheme definition describing their backing map.

Scheme Inheritance

Caching schemes can be defined by specifying all the elements required for a given scheme type, or by inheriting from another named scheme of the same type, and selectively overriding specific values. Scheme inheritance is accomplished by including a <scheme-ref> element in the inheriting scheme containing the scheme-name of the scheme to inherit from.

For example, the two configurations in Example D-2 will produce equivalent DistributedInMemoryCache scheme definitions:

Example D-2 Configuring Equivalent Scheme Definitions

<distributed-scheme>
  <scheme-name>DistributedInMemoryCache</scheme-name>
  <service-name>DistributedCache</service-name>
  <backing-map-scheme>
    <local-scheme>
      <eviction-policy>LRU</eviction-policy>
      <high-units>1000</high-units>
      <expiry-delay>1h</expiry-delay>
    </local-scheme>
  </backing-map-scheme>
</distributed-scheme>
<distributed-scheme>
  <scheme-name>DistributedInMemoryCache</scheme-name>
  <service-name>DistributedCache</service-name>
  <backing-map-scheme>
    <local-scheme>
      <scheme-ref>LocalSizeLimited</scheme-ref>
    </local-scheme>
  </backing-map-scheme>
</distributed-scheme>

<local-scheme>
  <scheme-name>LocalSizeLimited</scheme-name>
  <eviction-policy>LRU</eviction-policy>
  <high-units>1000</high-units>
  <expiry-delay>1h</expiry-delay>
</local-scheme>

Note that while the first is somewhat more compact, the second offers the ability to easily reuse the LocalSizeLimited scheme within multiple schemes. Example D-3 demonstrates multiple schemes reusing the same LocalSizeLimited base definition, but the second imposes a different expiry-delay.

Example D-3 Multiple Schemes Reusing the Same Base Definition

<distributed-scheme>
  <scheme-name>DistributedInMemoryCache</scheme-name>
  <service-name>DistributedCache</service-name>
  <backing-map-scheme>
    <local-scheme>
      <scheme-ref>LocalSizeLimited</scheme-ref>
    </local-scheme>
  </backing-map-scheme>
</distributed-scheme>

<replicated-scheme>
  <scheme-name>ReplicatedInMemoryCache</scheme-name>
  <service-name>ReplicatedCache</service-name>
  <backing-map-scheme>
    <local-scheme>
      <scheme-ref>LocalSizeLimited</scheme-ref>
      <expiry-delay>10m</expiry-delay>
    </local-scheme>
  </backing-map-scheme>
</replicated-scheme>

<local-scheme>
  <scheme-name>LocalSizeLimited</scheme-name>
  <eviction-policy>LRU</eviction-policy>
  <high-units>1000</high-units>
  <expiry-delay>1h</expiry-delay>
</local-scheme>

Elements

Table D-14 describes the different types of schemes you can define within the caching-schemes element.

Table D-14 caching-schemes Subelements

Element Required/Optional Description

<local-scheme>

Optional

Defines a cache scheme which provides on-heap cache storage.

<external-scheme>

Optional

Defines a cache scheme which provides off-heap cache storage, for instance on disk.

<paged-external-scheme>

Optional

Defines a cache scheme which provides off-heap cache storage, that is size-limited by using time based paging.

<distributed-scheme>

Optional

Defines a cache scheme where storage of cache entries is partitioned across the cluster nodes.

<replicated-scheme>

Optional

Defines a cache scheme where each cache entry is stored on all cluster nodes.

<optimistic-scheme>

Optional

Defines a replicated cache scheme which uses optimistic rather then pessimistic locking.

<near-scheme>

Optional

Defines a two tier cache scheme which consists of a fast local front-tier cache of a much larger back-tier cache.

<versioned-near-scheme>

Optional

Defines a near-scheme which uses object versioning to ensure coherence between the front and back tiers.

<overflow-scheme>

Optional

Defines a two tier cache scheme where entries evicted from a size-limited front-tier overflow and are stored in a much larger back-tier cache.

<invocation-scheme>

Optional

Defines an invocation service which can be used for performing custom operations in parallel across cluster nodes.

<read-write-backing-map-scheme>

Optional

Defines a backing map scheme which provides a cache of a persistent store.

<versioned-backing-map-scheme>

Optional

Defines a backing map scheme which uses object versioning to determine what updates need to be written to the persistent store.

<remote-cache-scheme>

Optional

Defines a cache scheme that enables caches to be accessed from outside a Coherence cluster by using Coherence*Extend.

<class-scheme>

Optional

Defines a cache scheme using a custom cache implementation. Any custom implementation must implement the java.util.Map interface, and include a zero-parameter public constructor. Additionally if the contents of the Map can be modified by anything other than the CacheService itself (for example, if the Map automatically expires its entries periodically or size-limits its contents), then the returned object must implement the com.tangosol.util.ObservableMap interface.

<disk-scheme>

Optional

Note: As of Coherence 3.0, the disk-scheme configuration element has been deprecated and replaced by the external-scheme and paged-external-scheme configuration elements.



class-scheme

Used in: caching-schemes, local-scheme, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, versioned-near-scheme, overflow-scheme, read-write-backing-map-scheme, versioned-backing-map-scheme, cachestore-scheme, listener

Description

Class schemes provide a mechanism for instantiating an arbitrary Java object for use by other schemes. The scheme which contains this element will dictate what class or interface(s) must be extended. See "Cache of a Database" for an example of using a class-scheme.

The class-scheme may be configured to either instantiate objects directly by using their class-name, or indirectly by using a class-factory-name and method-name. The class-scheme must be configured with either a class-name or class-factory-name and method-name.

Elements

Table D-15 describes the elements you can define within the class-scheme element.

Table D-15 class-scheme Subelements

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. See "Scheme Inheritance" for more information.

<class-name>

Optional

Contains a fully specified Java class name to instantiate. This class must extend an appropriate implementation class as dictated by the containing scheme and must declare the exact same set of public constructors as the superclass.

<class-factory-name>

Optional

Specifies a fully specified name of a Java class that will be used as a factory for object instantiation.

<method-name>

Optional

Specifies the name of a static factory method on the factory class which will perform object instantiation.

<init-params>

Optional

Specifies initialization parameters which are accessible by implementations which support the com.tangosol.run.xml.XmlConfigurable interface, or which include a public constructor with a matching signature.



custom-store-manager

Used in: external-scheme, paged-external-scheme, async-store-manager.

Description

Used to create and configure custom implementations of a store manager for use in external caches.

Elements

Table D-16 describes the elements you can define within the custom-store-manager element.

Table D-16 custom-store-manager Subelements

Element Required/Optional Description

<class-name>

Required

Specifies the implementation of the store manager. The specified class must implement the com.tangosol.io.BinaryStoreManager interface.

<init-params>

Optional

Specifies initialization parameters, for use in custom store manager implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.



disk-scheme

Note:

As of Coherence 3.0, the disk-scheme configuration element has been deprecated and replaced with by the <external-scheme> and <paged-external-scheme> configuration elements.

distributed-scheme

Used in: caching-schemes, near-scheme, versioned-near-scheme, overflow-scheme, versioned-backing-map-scheme

Description

The distributed-scheme defines caches where the storage for entries is partitioned across cluster nodes. See "Partitioned Cache Service" for a more detailed description of partitioned caches. See "Partitioned Cache" examples of various distributed-scheme configurations.

Clustered Concurrency Control

Partitioned caches support cluster wide key-based locking so that data can be modified in a cluster without encountering the classic missing update problem. Note that any operation made without holding an explicit lock is still atomic but there is no guarantee that the value stored in the cache does not change between atomic operations.

Cache Clients

The partitioned cache service supports the concept of cluster nodes which do not contribute to the overall storage of the cluster. Nodes which are not storage enabled (see <local-storage> subelement) are considered "cache clients".

Cache Partitions

The cache entries are evenly segmented into several logical partitions (see <partition-count> subelement), and each storage enabled (see <local-storage> subelement) cluster node running the specified partitioned service (see <service-name> subelement) will be responsible for maintain a fair-share of these partitions.

Key Association

By default the specific set of entries assigned to each partition is transparent to the application. In some cases it may be advantageous to keep certain related entries within the same cluster node. A key-associator (see <key-associator> subelement) may be used to indicate related entries, the partitioned cache service will ensure that associated entries reside on the same partition, and thus on the same cluster node. Alternatively, key association may be specified from within the application code by using keys which implement the com.tangosol.net.cache.KeyAssociation interface.

Cache Storage (Backing Map)

Storage for the cache is specified by using the backing-map-scheme (see <backing-map-scheme> subelement). For instance a partitioned cache which uses a local-scheme for its backing map will result in cache entries being stored in-memory on the storage enabled cluster nodes.

Failover

For the purposes of failover a configurable number of backups (see <backup-count> subelement) of the cache may be maintained in backup-storage (see <backup-storage> subelement) across the cluster nodes. Each backup is also divided into partitions, and when possible a backup partition will not reside on the same physical machine as the primary partition. If a cluster node abruptly leaves the cluster, responsibility for its partitions will automatically be reassigned to the existing backups, and new backups of those partitions will be created (on remote nodes) to maintain the configured backup count.

Partition Redistribution

When a node joins or leaves the cluster, a background redistribution of partitions occurs to ensure that all cluster nodes manage a fair-share of the total number of partitions. The amount of bandwidth consumed by the background transfer of partitions is governed by the transfer-threshold (see <transfer-threshold> subelement).

Elements

Table D-17 describes the elements you can define within the distributed-scheme element.

Table D-17 distributed-scheme Subelements

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. See "Scheme Inheritance" for more information.

<service-name>

Optional

Specifies the name of the service which will manage caches created from this scheme. Services are configured in the <services> element in the tangosol-coherence.xml descriptor. See Appendix H, "Operational Configuration Elements" for more information.

<serializer>

Optional

Specifies the class configuration info for a com.tangosol.io.Serializer implementation used by the Partitioned service to serialize and deserialize user types.

For example, the following configures a ConfigurablePofContext that uses the default coherence-pof-config.xml configuration file to write objects to and read from a stream:

<serializer>
  <class-name>com.tangosol.io.pof.ConfigurablePofContext</class-name>
</serializer>

<listener>

Optional

Specifies an implementation of a com.tangosol.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.

The content of the backing map scheme could start with an optional value:

<partitioned> – This optional value specifies whether the backing map itself is partitioned. It is respected only within a distributed-scheme. See "Storage" in the Oracle Coherence Getting Started Guide.

Legal child schemes are:

Note that when using an overflow-based backing map it is important that the corresponding <backup-storage> be configured for overflow (potentially using the same scheme as the backing-map). See "Partitioned Cache with Overflow" for an example configuration.

<partition-count>

Optional

Specifies the number of partitions that a partitioned (distributed) cache will be "chopped up" into. Each member running the partitioned cache service that has the local-storage (<local-storage> subelement) option set to true will manage a "fair" (balanced) number of partitions.

The number of partitions should be a prime number and sufficiently large such that a given partition is expected to be no larger than 50MB in size.

The following are good defaults for sample service storage sizes:

service storage     parition-count
_______________     ______________
   100M                  257
     1G                  509
    10G                 2039
    50G                 4093
   100G                 8191

A list of first 1,000 primes can be found at

http://primes.utm.edu/lists/

Valid values are positive integers. Default value is the value specified in the tangosol-coherence.xml descriptor. See the partition-count parameter "DistributedCache Service Parameters" for more information.

<key-associator>

Optional

Specifies a class that will be responsible for providing associations between keys and allowing associated keys to reside on the same partition. This implementation must have a zero-parameter public constructor.

<key-partitioning>

Optional

Specifies a class that implements the com.tangosol.net.partition.KeyPartitioningStrategy interface, which will be responsible for assigning keys to partitions. This implementation must have a zero-parameter public constructor. If unspecified, the default key partitioning algorithm will be used, which ensures that keys are evenly segmented across partitions.

<partition-listener>

Optional

Specifies a class that implements the com.tangosol.net.partition.PartitionListener interface.

<backup-count>

Optional

Specifies the number of members of the partitioned cache service that hold the backup data for each unit of storage in the cache. Value of 0 means that in the case of abnormal termination, some portion of the data in the cache will be lost. Value of N means that if up to N cluster nodes terminate immediately, the cache data will be preserved. To maintain the partitioned cache of size M, the total memory usage in the cluster does not depend on the number of cluster nodes and will be in the order of M*(N+1). Recommended values are 0 or 1. Default value is the backup-count value specified in the tangosol-coherence.xml descriptor. See the backup-count parameter in value specified in the tangosol-coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.

<backup-count-after- writebehind>

Optional

Specifies the number of members of the partitioned cache service that will hold the backup data for each unit of storage in the cache that does not require write-behind, that is, data that is not vulnerable to being lost even if the entire cluster were shut down. Specifically, if a unit of storage is marked as requiring write-behind, then it will be backed up on the number of members specified by the <backup-count> subelement, and if the unit of storage is not marked as requiring write-behind, then it will be backed up by the number of members specified by the <backup-count-after-writebehind> element.

This value should be set to 0 or this setting should not be specified at all. The rationale is that since this data is being backed up to another data store, no in-memory backup is required, other than the data temporarily queued on the write-behind queue to be written. (Note that the setting also applies to write-through data, or any data that can be re-loaded from another data store by a CacheLoader or CacheStore.) The value of 0 means that when write-behind has occurred, the backup copies of that data will be discarded. However, until write-behind occurs, the data will be backed up in accordance with the <backup-count> setting.

Recommended value is 0 or this element should be omitted altogether.

<backup-storage>

Optional

Specifies the type and configuration for the partitioned cache backup storage.

<thread-count>

Optional

Specifies the number of daemon threads used by the partitioned cache service. If zero, all relevant tasks are performed on the service thread. Legal values are positive integers or zero. Default value is the thread-count value specified in the tangosol-coherence.xml descriptor. See the lthread-count parameter in "DistributedCache Service Parameters" for more information.

<lease-granularity>

Optional

Specifies the lease ownership granularity. Available since release 2.3.Legal values are:

  • thread

  • member

A value of thread means that locks are held by a thread that obtained them and can only be released by that thread. A value of member means that locks are held by a cluster node and any thread running on the cluster node that obtained the lock can release it. Default value is the lease-granularity value specified in the tangosol-coherence.xml descriptor. See the lease-granularity parameter in "DistributedCache Service Parameters" for more information.

<transfer-threshold>

Optional

Specifies the threshold for the primary buckets distribution in kilo-bytes. When a new node joins the partitioned cache service or when a member of the service leaves, the remaining nodes perform a task of bucket ownership re-distribution. During this process, the existing data gets re-balanced along with the ownership information. This parameter indicates a preferred message size for data transfer communications. Setting this value lower will make the distribution process take longer, but will reduce network bandwidth utilization during this activity. Legal values are integers greater then zero. Default value is the transfer-threshold value specified in the tangosol-coherence.xml descriptor. See the transfer-threshold parameter in "DistributedCache Service Parameters" for more information.

<local-storage>

Optional

Specifies whether a cluster node will contribute storage to the cluster, that is, maintain partitions. When disabled the node is considered a cache client.

Normally this value should be left unspecified within the configuration file, and instead set on a per-process basis using the tangosol.coherence.distributed.localstorage system property. This allows cache clients and servers to use the same configuration descriptor.

Legal values are true or false. Default value is the local-storage value specified in the tangosol-coherence.xml descriptor. See the local-storage parameter in "DistributedCache Service Parameters" for more information.

<autostart>

Optional

The autostart element is intended to be used by cache servers (that is, com.tangosol.net.DefaultCacheServer). It specifies whether 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.

<task-hung-threshold>

Optional

Specifies the amount of time in milliseconds that a task can execute before it is considered "hung". Note: a posted task that has not yet started is never considered as hung. This attribute is applied only if the Thread pool is used (the thread-count value is positive). Legal values are positive integers or zero (indicating no default timeout). Default value is the task-hung-threshold value specified in the tangosol-coherence.xml descriptor. See the task-hung-threshold parameter in "DistributedCache Service Parameters" for more information.

<task-timeout>

Optional

Specifies the timeout value in milliseconds for requests executing on the service worker threads. This attribute is applied only if the thread pool is used (the thread-count value is positive). If zero is specified, the default service-guardian <timeout-milliseconds> value is used. Legal values are non-negative integers. Default value is the value specified in the tangosol-coherence.xml descriptor. See the task-timeout parameter in "DistributedCache Service Parameters".

<request-timeout>

Optional

Specifies the maximum amount of time a client will wait for a response before abandoning the original request. The request time is measured on the client side as the time elapsed from the moment a request is sent for execution to the corresponding server node(s) and includes the following:

  • the time it takes to deliver the request to an executing node (server)

  • the interval between the time the task is received and placed into a service queue until the execution starts

  • the task execution time

  • the time it takes to deliver a result back to the client

Legal values are positive integers or zero (indicating no default timeout). Default value is the value specified in the tangosol-coherence.xml descriptor. See the request-timeout parameter in "DistributedCache Service Parameters" for more information.

<operation-bundling>

Optional

Specifies the configuration info for a bundling strategy.



external-scheme

Used in: caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, versioned-near-scheme, overflow-scheme, read-write-backing-map-scheme, versioned-backing-map-scheme

Description

External schemes define caches which are not JVM heap based, allowing for greater storage capacity. See "Local Caches (accessible from a single JVM)" for examples of various external cache configurations.

Implementation

This scheme is implemented by:

The implementation type is chosen based on the following rule:

Pluggable Storage Manager

External schemes use a pluggable store manager to store and retrieve binary key value pairs. Supported store managers include:

Size Limited Cache

The cache may be configured as size-limited, which means that when it reaches its maximum allowable size (that is, the <high-units> subelement) it prunes itself.

Note:

Eviction against disk-based caches can be expensive, consider using a paged-external-scheme for such cases.

Entry Expiration

External schemes support automatic expiration of entries based on the age of the value, as configured by the <expiry-delay> subelement.

Persistence (long-term storage)

External caches are generally used for temporary storage of large data sets, for example as the back-tier of an overflow-scheme. Certain implementations do however support persistence for non-clustered caches, see the <store-name> subelement of bdb-store-manager and the <manager-filename> subelement of lh-file-manager for details. Clustered persistence should be configured by using a read-write-backing-map-scheme on a distributed-scheme.

Elements

Table D-18 describes the elements you can define within the external-scheme element.

Table D-18 external-scheme Subelements

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. See "Scheme Inheritance" for more information

<class-name>

Optional

Specifies a custom implementation of the external cache. Any custom implementation must extend one of the following classes:

and declare the exact same set of public constructors as the superclass.

<init-params>

Optional

Specifies initialization parameters, for use in custom external cache implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<listener>

Optional

Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache.

<high-units>

Optional

Used to limit the size of the cache. Contains the maximum number of units that can be placed in the cache before pruning occurs. An entry is the unit of measurement. When 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. The scheme's class-name element may be used to provide custom extensions to SerializationCache, which implement alternative eviction policies. Legal values are positive integers or zero. Zero implies no limit. Default value is zero.

<unit-calculator>

Optional

Specifies the type of unit calculator to use. A unit calculator is used to determine the cost (in "units") of a given object.Legal values are:

This element is used only if the high-units element is set to a positive number. Default value is FIXED.

<unit-factor>

Optional

The unit-factor element specifies the factor by which the units, low-units and high-units properties are adjusted. Using a BINARY unit calculator, for example, the factor of 1048576 could be used to count megabytes instead of bytes.

Using a BINARY unit calculator, for example, the factor of 1048576 could be used to count megabytes instead of bytes.

Note: This element was introduced only to avoid changing the type of the units, low units and high units properties from 32-bit values to 64-bit values and is used only if the high-units element is set to a positive number. It is expected that this element will be dropped in Coherence 4.

Valid values are positive integer numbers. Default value is 1.

<expiry-delay>

Optional

Specifies the amount of time from last update that entries will be kept by the cache before being expired. Entries that are expired will not be accessible and will be evicted.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of seconds is assumed. A value of zero implies no expiry. Default value is zero.

<async-store-manager>

Optional

Configures the external cache to use an asynchronous storage manager wrapper for any other storage manager. See "Pluggable Storage Manager"

<custom-store-manager>

Optional

Configures the external cache to use a custom storage manager implementation.

<bdb-store-manager>

Optional

Configures the external cache to use Berkeley Database JE on disk databases for cache storage.

<lh-file-manager>

Optional

Configures the external cache to use a Coherence LH on disk database for cache storage.

<nio-file-manager>

Optional

Configures the external cache to use a memory-mapped file for cache storage.

<nio-memory-manager>

Optional

Configures the external cache to use an off JVM heap, memory region for cache storage.



initiator-config

Used in: remote-cache-scheme, remote-invocation-scheme.

Description

The initiator-config element specifies the configuration info for a protocol-specific connection initiator. A connection initiator allows a Coherence*Extend client to connect to a cluster (by using a connection acceptor) and use the clustered services offered by the cluster without having to first join the cluster.

The initiator-config element must contain exactly one protocol-specific connection initiator configuration element (either jms-initiator or tcp-initiator).

Elements

Table D-19 describes the elements you can define within the initiator-config element.

Table D-19 initiator-config Subelements

Element Required/Optional Description

<jms-initiator>

Optional

Specifies the configuration info for a connection initiator that connects to the cluster over JMS.

<outgoing-message-handler>

Optional

Specifies the configuration info used by the connection initiator to detect dropped client-to-cluster connections.

<serializer>

Optional

Specifies the class configuration info for a Serializer implementation used by the connection initiator to serialize and deserialize user types. For example, the following configures a ConfigurablePofContext that uses the my-pof-types.xml POF type configuration file to deserialize user types to and from a POF stream:

<serializer>
  <class-name>com.tangosol.io.pof.ConfigurablePofContext</class-name>
  <init-params>
    <init-param>
      <param-type>string</param-type>
      <param-value>my-pof-types.xml</param-value>
    </init-param>
  </init-params>
</serializer>

<tcp-initiator>

Optional

Specifies the configuration info for a connection initiator that connects to the cluster over TCP/IP.

<use-filters>

Optional

Contains the list of <filters> names to be used by this connection initiator. In the following example, specifying use-filter will activate gzip compression for all network messages, which can help substantially with WAN and low-bandwidth networks.

<use-filters>
    <filter-name>gzip</filter-name>
</use-filters>


init-param

Used in: init-params.

Defines an individual initialization parameter.

Elements

Table D-20 describes the elements you can define within the init-param element.

Table D-20 init-param Subelements

Element Required/Optional Description

<param-name>

Optional

Contains the name of the initialization parameter. For example:

<class-name>com.mycompany.cache.CustomCacheLoader</class-name>
<init-params>
  <init-param>
    <param-name>sTableName</param-name>
    <param-value>EmployeeTable</param-value>
  </init-param>
  <init-param>
    <param-name>iMaxSize</param-name>
    <param-value>2000</param-value>
  </init-param>
</init-params>

<param-type>

Optional

Contains the Java type of the initialization parameter.The following standard types are supported:

  • java.lang.String (a.k.a. string)

  • java.lang.Boolean (a.k.a. boolean)

  • java.lang.Integer (a.k.a. int)

  • java.lang.Long (a.k.a. long)

  • java.lang.Double (a.k.a. double)

  • java.math.BigDecimal

  • java.io.File

  • java.sql.Date

  • java.sql.Time

  • java.sql.Timestamp

For example:

<class-name>com.mycompany.cache.CustomCacheLoader</class-name>
<init-params>
  <init-param>
    <param-type>java.lang.String</param-type>
    <param-value>EmployeeTable</param-value>
  </init-param>
  <init-param>
    <param-type>int</param-type>
    <param-value>2000</param-value>
  </init-param>
</init-params>

Please refer to the list of available Appendix E, "Cache Configuration Parameter Macros".

<param-value>

Optional

Contains the value of the initialization parameter. The value is in the format specific to the Java type of the parameter. See Appendix E, "Cache Configuration Parameter Macros" for the list of available macros.



init-params

Used in: class-scheme, cache-mapping.

Description

Defines a series of initialization parameters as name-value pairs. See "Cache of a Database" for an example of using init-params.

Elements

Table D-21 describes the elements you can define within the init-params element.

Table D-21 init-params Subelements

Element Required/Optional Description

<init-param>

Optional

Defines an individual initialization parameter.



invocation-scheme

Used in: caching-schemes.

Description

Defines an Invocation Service. The invocation service may be used to perform custom operations in parallel on any number of cluster nodes. See the com.tangosol.net.InvocationService API for additional details.

Elements

The following table describes the elements you can define within the invocation-scheme element.

Table D-22 invocation-scheme Subelements

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 from. See "Scheme Inheritance" for more information.

<service-name>

Optional

Specifies the name of the service which will manage invocations from this scheme.

<serializer>

Optional

Specifies the class configuration info for a com.tangosol.io.Serializer implementation used by the Invocation service to serialize and deserialize user types. For example, the following configures a ConfigurablePofContext that uses the default coherence-pof-types.xml configuration file to write objects to and read from a stream:

<serializer>
  <class-name>com.tangosol.io.pof.ConfigurablePofContext</class-name>
</serializer>

Services are configured from within the <services> element in the tangosol-coherence.xml descriptor. See Appendix H, "Operational Configuration Elements" for more information.

<thread-count>

Optional

Specifies the number of daemon threads used by the invocation service. If zero, all relevant tasks are performed on the service thread. Legal values are positive integers or zero. Default value is the thread-count value specified in the tangosol-coherence.xml descriptor. See the thread-count parameter in "InvocationService Parameters".

<autostart>

Optional

The autostart element is intended to be used by cache servers (that is, com.tangosol.net.DefaultCacheServer). It specifies whether this service should be automatically started at a cluster node. Legal values are true or false. Default value is false.

<task-hung-threshold>

Optional

Specifies the amount of time in milliseconds that a task can execute before it is considered "hung". Note: a posted task that has not yet started is never considered as hung. This attribute is applied only if the Thread pool is used (the thread-count value is positive). Legal values are positive integers or zero (indicating no default timeout). Default value is the task-hung-threshold value specified in the tangosol-coherence.xml descriptor. See the task-hung-threshold parameter in "InvocationService Parameters".

<task-timeout>

Optional

Specifies the default timeout value in milliseconds for tasks that can be timed-out (for example, implement the com.tangosol.net.PriorityTask interface), but don't explicitly specify the task execution timeout value. The task execution time is measured on the server side and does not include the time spent waiting in a service backlog queue before being started. This attribute is applied only if the thread pool is used (the thread-count value is positive). If zero is specified, the default service-guardian <timeout-milliseconds> value is used. Legal values are non-negative integers. Default value is the task-timeout value specified in the tangosol-coherence.xml descriptor. See the task-timeout parameter in "InvocationService Parameters".

<request-timeout>

Optional

Specifies the default timeout value in milliseconds for requests that can time-out (for example, implement the com.tangosol.net.PriorityTask interface), but don't explicitly specify the request timeout value. The request time is measured on the client side as the time elapsed from the moment a request is sent for execution to the corresponding server node(s) and includes the following:

(1) the time it takes to deliver the request to an executing node (server); (2) the interval between the time the task is received and placed into a service queue until the execution starts; (3) the task execution time; (4) the time it takes to deliver a result back to the client.

Legal values are positive integers or zero (indicating no default timeout). Default value is the request-timeout value specified in the tangosol-coherence.xml descriptor. See the request-timeout parameter in "InvocationService Parameters".



invocation-service-proxy

Used in: proxy-config

Description

The invocation-service-proxy element contains the configuration info for an invocation service proxy managed by a proxy service.

Elements

Table D-23 describes the elements you can define within the invocation-service-proxy element.

Table D-23 invocation-service-proxy Subelement

Element Required/Optional Description

<enabled>

Optional

Specifies whether the invocation service proxy is enabled. If disabled, clients will not be able to execute Invocable objects on the proxy service JVM. Legal values are true or false. Default value is true.



jms-acceptor

Note:

Coherence*Extend-JMS support has been deprecated.

Used in: acceptor-config.

Description

The jms-acceptor element specifies the configuration info for a connection acceptor that accepts connections from Coherence*Extend clients over JMS. For additional details and example configurations see Chapter 17, "Configuring and Using Coherence*Extend."

Elements

Table D-24 describes the elements you can define within the jms-acceptor element.

Table D-24 jms-acceptor Subelements

Element Required/Optional Description

<queue-connection-factory-name>

Required

Specifies the JNDI name of the JMS QueueConnectionFactory used by the connection acceptor.

<queue-name>

Required

Specifies the JNDI name of the JMS Queue used by the connection acceptor.



jms-initiator

Note:

Coherence*Extend-JMS support has been deprecated.

Used in: initiator-config.

Description

The jms-initiator element specifies the configuration info for a connection initiator that enables Coherence*Extend clients to connect to a remote cluster by using JMS. For additional details and example configurations see Chapter 17, "Configuring and Using Coherence*Extend."

Elements

The following table describes the elements you can define within the jms-initiator element.

Table D-25 jms-initiator Subelements

Element Required/Optional Description

<queue-connection-factory-name>

Required

Specifies the JNDI name of the JMS QueueConnectionFactory used by the connection initiator.

<queue-name>

Required

Specifies the JNDI name of the JMS Queue used by the connection initiator.

<connect-timeout>

Optional

Specifies the maximum amount of time to wait while establishing a connection with a connection acceptor. The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of milliseconds is assumed. Default value is an infinite timeout.



key-associator

Used in: distributed-scheme

Description

Specifies an implementation of a com.tangosol.net.partition.KeyAssociator which will be used to determine associations between keys, allowing related keys to reside on the same partition.

Alternatively the cache's keys may manage the association by implementing the com.tangosol.net.cache.KeyAssociation interface.

Elements

Table D-26 describes the elements you can define within the key-associator element.

Table D-26 key-associator Subelements

Element Required/Optional Description

<class-name>

Required

The name of a class that implements the com.tangosol.net.partition.KeyAssociator interface. This implementation must have a zero-parameter public constructor. Default value is the value of the key-associator/class-name parameter specified in the tangosol.coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.



key-partitioning

Used in: distributed-scheme

Description

Specifies an implementation of a com.tangosol.net.partition.KeyPartitioningStrategy which will be used to determine the partition in which a key will reside.

Elements

Table D-27 describes the elements you can define within the key-partitioning element.

Table D-27 key-partitioning Subelements

Element Required/Optional Description

<class-name>

Required

The name of a class that implements the com.tangosol.net.partition.KeyPartitioningStrategy interface. This implementation must have a zero-parameter public constructor. Default value is the value of the key-partitioning/class-name parameter specified in the tangosol-coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.



lh-file-manager

Used in: external-scheme, paged-external-scheme, async-store-manager.

Description

Configures a store manager which will use a Coherence LH on disk embedded database for storage. See "Persistent Cache on Disk" and "In-memory Cache with Disk Based Overflow" for examples of LH-based store configurations.

Implementation

Implemented by the com.tangosol.io.lh.LHBinaryStoreManager class. The BinaryStore objects created by this class are instances of javadoc:com.tangosol.io.lh.LHBinaryStore.

Elements

Table D-28 describes the elements you can define within the lh-file-manager element.

Table D-28 lh-file-manager Subelements

Element Required/Optional Description

<class-name>

Optional

Specifies a custom implementation of the LH BinaryStoreManager. Any custom implementation must extend the com.tangosol.io.lh.LHBinaryStoreManager class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom LH file manager implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<directory>

Optional

Specifies the path name for the root directory that the LH file manager will use to store files in. If not specified or specifies a non-existent directory, a temporary file in the default location will be used.

<file-name>

Optional

Specifies the name for a non-temporary (persistent) file that the LH file manager will use to store data in. Specifying this parameter will cause the lh-file-manager to use non-temporary database instances. Use this parameter only for local caches that are backed by a cache loader from a non-temporary file: this allows the local cache to be pre-populated from the disk file on startup. When specified it is recommended that it use the {cache-name} macro described in Appendix E, "Cache Configuration Parameter Macros" macro. Normally this parameter should be left unspecified, indicating that temporary storage is to be used.



listener

Used in: local-scheme, external-scheme, paged-external-scheme, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, versioned-near-scheme, overflow-scheme, read-write-backing-map-scheme, versioned-backing-map-scheme.

Description

The Listener element specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on a cache.

Elements

The following table describes the elements you can define within the listener element.

Table D-29 listener Subelement

Element Required/Optional Description

<class-scheme>

Required

Specifies the full class name of the listener implementation to use. The specified class must implement the com.tangosol.util.MapListener interface.



local-scheme

Used in: caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, versioned-near-scheme, overflow-scheme, read-write-backing-map-scheme, versioned-backing-map-scheme

Description

Local cache schemes define in-memory "local" caches. Local caches are generally nested within other cache schemes, for instance as the front-tier of a near-scheme. See "Local Cache of a Partitioned Cache (Near cache)" for examples of various local cache configurations.

Implementation

Local caches are implemented by the com.tangosol.net.cache.LocalCache class.

Cache of an External Store

A local cache may be backed by an external cache store (see "cachestore-scheme"). Cache misses will read-through to the back end store to retrieve the data. If a writable store is provided, cache writes will propagate to the cache store as well. For optimizing read/write access against a cache store, see the "read-write-backing-map-scheme".

Size Limited Cache

The cache may be configured as size-limited, which means that when it reaches its maximum allowable size (see <allowable-size> subelement) it prunes itself back to a specified smaller size (see <low-units> subelement), choosing which entries to evict according to its eviction-policy (see <eviction-policy> subelement). The entries and size limitations are measured in terms of units as calculated by the scheme's unit-calculator (see <unit-calculator> subelement).

Entry Expiration

The local cache supports automatic expiration of entries based on the age of the value, as configured by the expiry-delay (see <expiry-delay> subelement).

Elements

Table D-30 describes the elements you can define within the local-scheme element.

Table D-30 local-scheme Subelements

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. See "Scheme Inheritance" for more information.

<service-name>

Optional

Specifies the name of the service which will manage caches created from this scheme. Services are configured from within the <services> element in the tangosol-coherence.xml descriptor. See Appendix H, "Operational Configuration Elements" for more information.

<class-name>

Optional

Specifies a custom implementation of the local cache. Any custom implementation must extend the com.tangosol.net.cache.LocalCache class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom local cache implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<listener>

Optional

Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache.

<cachestore-scheme>

Optional

Specifies the store which is being cached. If unspecified the cached data will only reside in memory, and only reflect operations performed on the cache itself.

<eviction-policy>

Optional

Specifies the type of eviction policy to use.Legal values are:

  • LRU - Least Recently Used eviction policy chooses which entries to evict based on how recently they were last accessed, evicting those that were not accessed the for the longest period first.

  • LFU - Least Frequently Used eviction policy chooses which entries to evict based on how often they are being accessed, evicting those that are accessed least frequently first.

  • HYBRID - Hybrid eviction policy chooses which entries to evict based the combination (weighted score) of how often and recently they were accessed, evicting those that are accessed least frequently and were not accessed for the longest period first.

  • <class-scheme> - A custom eviction policy, specified as a class-scheme. The class specified within this scheme must implement the com/tangosol/net/cache/ConfigurableCacheMap.EvictionPolicy interface.

Default value is HYBRID.

<high-units>

Optional

Used to limit the size of the cache. Contains the maximum number of units that can be placed in the cache before pruning occurs. An entry is the unit of measurement, unless it is overridden by an alternate unit-calculator (see <unit-calculator> subelement). When this limit is exceeded, the cache will begin the pruning process, evicting entries according to the eviction policy until the low-units (see <low-units> subelement) size is reached. Legal values are positive integers or zero. Zero implies no limit. Default value is 0.

<low-units>

Optional

Contains the number of units that the cache will be pruned down to when pruning takes place. An entry is the unit of measurement, unless it is overridden by an alternate unit-calculator (see <unit-calculator> subelement). When pruning occurs entries will continue to be evicted according to the eviction policy until this size. Legal values are positive integers or zero. Zero implies the default. Default value is 75% of the high-units setting (that is, for a high-units setting of 1000 the default low-units will be 750).

<unit-calculator>

Optional

Specifies the type of unit calculator to use. A unit calculator is used to determine the cost (in "units") of a given object.Legal values are:

This element is used only if the high-units element is set to a positive number. Default value is FIXED.

<unit-factor>

Optional

The unit-factor element specifies the factor by which the units, low-units and high-units properties are adjusted. Using a BINARY unit calculator, for example, the factor of 1048576 could be used to count megabytes instead of bytes.

Using a BINARY unit calculator, for example, the factor of 1048576 could be used to count megabytes instead of bytes.

Note: This element was introduced only to avoid changing the type of the units, low units and high units properties from 32-bit values to 64-bit values and is used only if the high-units element is set to a positive number. It is expected that this element will be dropped in Coherence 4.

Valid values are positive integer numbers. Default value is 1.

<unit-factor>

Optional

The unit-factor element specifies the factor by which the units, low-units and high-units properties are adjusted. Using a BINARY unit calculator, for example, the factor of 1048576 could be used to count megabytes instead of bytes.

Valid values are positive integer numbers. Default value is 1.

Note: This element was introduced only to avoid changing the type of the units, low units and high units properties from 32-bit values to 64-bit values.

<expiry-delay>

Optional

Specifies the amount of time from last update that entries will be kept by the cache before being marked as expired. Any attempt to read an expired entry will result in a reloading of the entry from the configured cache store (see <cachestore-scheme>. Expired values are periodically discarded from the cache based on the flush-delay (see <flush-delay> subelement). The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of seconds is assumed. A value of zero implies no expiry. Default value is zero.

<flush-delay>

Optional

Specifies the time interval between periodic cache flushes, which will discard expired entries from the cache, thus freeing resources.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of seconds is assumed. If <expiry-delay> is enabled, the default flush-delay is 1m, otherwise a default of zero is used and automatic flushes are disabled.



near-scheme

Used in: caching-schemes.

Description

The near-scheme defines a two-tier cache consisting of a front-tier (see <front-scheme> subelement) which caches a subset of a back-tier cache (see <back-scheme> subelement). The front-tier is generally a fast, size limited cache, while the back-tier is slower, but much higher capacity. A typical deployment might use a local-scheme for the front-tier, and a distributed-scheme for the back-tier. The result is that a portion of a large partitioned cache will be cached locally in-memory allowing for very fast read access. See Appendix B, "Types of Caches in Coherence," for a more detailed description of near caches, and "Local Cache of a Partitioned Cache (Near cache)" for an example of near cache configurations.

Implementation

The near scheme is implemented by the com.tangosol.net.cache.NearCache class.

Front-tier Invalidation

Specifying an invalidation-strategy (see <invalidation-strategy> subelement) defines a strategy that is used to keep the front tier of the near cache in sync with the back tier. Depending on that strategy a near cache is configured to listen to certain events occurring on the back tier and automatically update (or invalidate) the front portion of the near cache.

Elements

Table D-31 describes the elements you can define within the near-scheme element.

Table D-31 near-scheme Subelements

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. See "Scheme Inheritance" for more information

<class-name>

Optional

Specifies a custom implementation of the near cache. Any custom implementation must extend the com.tangosol.net.cache.NearCache class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters for custom near cache implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<listener>

Optional

Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache.

<front-scheme>

Required

Specifies the cache-scheme to use in creating the front-tier cache.Legal values are:

The eviction policy of the front-scheme defines which entries will be cached locally. For example:

<front-scheme>
  <local-scheme>
    <eviction-policy>HYBRID</eviction-policy>
    <high-units>1000</high-units>
  </local-scheme>
</front-scheme>

<back-scheme>

Required

Specifies the cache-scheme to use in creating the back-tier cache. Legal values are:

For example:

<back-scheme>
  <distributed-scheme>
    <scheme-ref>default-distributed</scheme-ref>
  </distributed-scheme>
</back-scheme>

<invalidation-strategy>

Optional

Specifies the strategy used keep the front-tier in-sync with the back-tier. Please see com.tangosol.net.cache.NearCache for more details.Legal values are:

  • none - instructs the cache not to listen for invalidation events at all. This is the best choice for raw performance and scalability when business requirements permit the use of data which might not be absolutely current. Freshness of data can be guaranteed by use of a sufficiently brief eviction policy. The worst case performance is identical to a standard Distributed cache.

  • present - instructs the near cache to listen to the back map events related only to the items currently present in the front map. This strategy works best when cluster nodes have sticky data access patterns (for example, HTTP session management with a sticky load balancer).

  • all - instructs the near cache to listen to all back map events. This strategy is optimal for read-heavy access patterns where there is significant overlap between the front caches on each cluster member.

  • auto - instructs the near cache to switch between present and all strategies automatically based on the cache statistics.

Default value is auto.

<autostart>

Optional

The autostart element is intended to be used by cache servers (that is, com.tangosol.net.DefaultCacheServer). It specifies whether 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.



nio-file-manager

Used in: external-scheme, paged-external-scheme, async-store-manager.

Description

Configures an external store which uses memory-mapped file for storage.

Implementation

This store manager is implemented by the com.tangosol.io.nio.MappedStoreManager class. The BinaryStore objects created by this class are instances of the com.tangosol.io.nio.BinaryMapStore.

Elements

Table D-32 describes the elements you can define within the nio-file-manager element.

Table D-32 nio-file-manager Subelements

Element Required/Optional Description

<class-name>

Optional

Specifies a custom implementation of the local cache. Any custom implementation must extend the com.tangosol.io.nio.MappedStoreManager class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom nio-file-manager implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<initial-size>

Optional

Specifies the initial buffer size in megabytes.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of mega is assumed. Legal values are positive integers between 1 and Integer.MAX_VALUE - 1023 (that is, 2,147,482,624 bytes). Default value is 1MB.

<maximum-size>

Optional

Specifies the maximum buffer size in bytes.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of mega is assumed. Legal values are positive integers between 1 and Integer.MAX_VALUE - 1023 (that is, 2,147,482,624 bytes). Default value is 1024MB.

<directory>

Optional

Specifies the path name for the root directory that the manager will use to store files in. If not specified or specifies a non-existent directory, a temporary file in the default location will be used.



nio-memory-manager

Used in: external-scheme, paged-external-scheme, async-store-manager.

Description

Configures a store-manager which uses an off JVM heap, memory region for storage, which means that it does not affect the Java heap size and the related JVM garbage-collection performance that can be responsible for application pauses. See "NIO In-memory Cache" for an example of an NIO cache configuration.

Note:

Some JVMs (starting with 1.4) require the use of a command line parameter if the total NIO buffers will be greater than 64MB. For example: -XX:MaxDirectMemorySize=512M

Implementation

Implemented by the com.tangosol.io.nio.DirectStoreManager class. The BinaryStore objects created by this class are instances of the com.tangosol.io.nio.BinaryMapStore.

Elements

Table D-33 describes the elements you can define within the nio-memory-manager element.

Table D-33 nio-memory-manager Subelements

Element Required/Optional Description

<class-name>

Optional

Specifies a custom implementation of the local cache. Any custom implementation must extend the com.tangosol.io.nio.DirectStoreManager class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom nio-memory-manager implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<initial-size>

Optional

Specifies the initial buffer size in bytes. The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of mega is assumed. Legal values are positive integers between 1 and Integer.MAX_VALUE - 1023 (that is, 2,147,482,624 bytes). Default value is 1MB.

<maximum-size>

Optional

Specifies the maximum buffer size in bytes. The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of mega is assumed. Legal values are positive integers between 1 and Integer.MAX_VALUE - 1023 (that is, 2,147,482,624 bytes). Default value is 1024MB.



operation-bundling

Used in: cachestore-scheme, distributed-scheme, remote-cache-scheme.

Description

The operation-bundling element specifies the configuration info for a particular bundling strategy.

Bundling is a process of coalescing multiple individual operations into "bundles". It could be beneficial when

See com.tangosol.net.cache.AbstractBundler for additional implementation details.

Elements

Table D-34 describes the subelement for the operation-bundling element.

Table D-34 operation-bundling Subelement

Element Required/Optional Description

<bundle-config>

Required

Describes one or more bundle-able operations.



optimistic-scheme

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 run the service (see <service-name> subelement). See Appendix B, "Types of Caches in Coherence" for a more detailed description of optimistic caches.

Optimistic Locking

Unlike the replicated-scheme and distributed-scheme 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.

Cache Storage (Backing Map)

Storage for the cache is specified by using the backing-map-scheme (see <backing-map-scheme> subelement). For instance an optimistic cache which uses a local-scheme for its backing map will result in cache entries being stored in-memory.

Elements

Table D-35 describes the elements you can define within the optimistic-scheme element.

Table D-35 optimistic-scheme Subelements

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. See "Scheme Inheritance" for more information.

<service-name>

Optional

Specifies the name of the service which will manage caches created from this scheme. Services are configured from within the <services> parameter in tangosol-coherence.xml. See Appendix H, "Operational Configuration Elements" for more information.

<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:

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 (that is, com.tangosol.net.DefaultCacheServer). It specifies whether 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.



outgoing-message-handler

Used in: acceptor-config, initiator-config.

Description

The outgoing-message-handler specifies the configuration info used to detect dropped client-to-cluster connections. For connection initiators and acceptors that use connectionless protocols, this information is necessary to proactively detect and release resources allocated to dropped connections. Connection-oriented initiators and acceptors can also use this information as an additional mechanism to detect dropped connections.

Elements

Table D-36 describes the elements you can define within the outgoing-message-handler element.

Table D-36 outgoing-message-handler Subelements

Element Required/Optional Description

<heartbeat-interval>

Optional

Specifies the interval between ping requests. A ping request is used to ensure the integrity of a connection.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of milliseconds is assumed. A value of zero disables ping requests. The default value is zero.

<heartbeat-timeout>

Optional

Specifies the maximum amount of time to wait for a response to a ping request before declaring the underlying connection unusable.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of milliseconds is assumed. The default value is the value of the request-timeout element.

<request-timeout>

Optional

Specifies the maximum amount of time to wait for a response message before declaring the underlying connection unusable.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of milliseconds is assumed. The default value is an infinite timeout.



overflow-scheme

Used in: caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme, read-write-backing-map-scheme, versioned-backing-map-scheme.

Description

The overflow-scheme defines a two-tier cache consisting of a fast, size limited front-tier, and slower but much higher capacity back-tier cache. When the size limited front fills up, evicted entries are transparently moved to the back. In the event of a cache miss, entries may move from the back to the front. A typical deployment might use a local-scheme for the front-tier, and a external-scheme for the back-tier, allowing for fast local caches with capacities larger the JVM heap would allow. In such a deployment the local-scheme element's high-units and eviction-policy will control the transfer (eviction) of entries from the front to back caches.

Note:

Relying on overflow for normal cache storage is not recommended. It should only be used to help avoid eviction-related data loss in the case where the storage requirements temporarily exceed the configured capacity. In general, the overflow's on disk storage should remain empty.

Implementation

Implemented by either com.tangosol.net.cache.OverflowMap or com.tangosol.net.cache.SimpleOverflowMap, see expiry-enabled for details.

Entry Expiration

Overflow supports automatic expiration of entries based on the age of the value, as configured by the expiry-delay (see <expiry-delay> subelement).

Elements

Table D-37 describes the elements you can define within the overflow-scheme element.

Table D-37 overflow-scheme Subelements

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. See "Scheme Inheritance" for more information.

<class-name>

Optional

Specifies a custom implementation of the overflow cache. Any custom implementation must extend either the com.tangosol.net.cache.OverflowMap or com.tangosol.net.cache.SimpleOverflowMap class, and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom overflow cache implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<listener>

Optional

Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache.

<front-scheme>

Required

Specifies the cache-scheme to use in creating the front-tier cache.Legal values are:

The eviction policy of the front-scheme defines which entries which items are in the front versus back tiers. For example:

<front-scheme>
  <local-scheme>
    <eviction-policy>HYBRID</eviction-policy>
    <high-units>1000</high-units>
  </local-scheme>
</front-scheme>

<back-scheme>

Required

Specifies the cache-scheme to use in creating the back-tier cache.Legal values are:

For Example:

<back-scheme>
  <external-scheme>
    <lh-file-manager/>
  </external-scheme>
</back-scheme>

<miss-cache-scheme>

Optional

Specifies a cache-scheme for maintaining information on cache misses. For caches which are not expiry-enabled (see <expiry-enabled> subelement), the miss-cache is used track keys which resulted in both a front and back tier cache miss. The knowledge that a key is not in either tier allows some operations to perform faster, as they can avoid querying the potentially slow back-tier. A size limited scheme may be used to control how many misses are tracked. If unspecified no cache-miss data will be maintained. Legal values are:

<expiry-enabled>

Optional

Turns on support for automatically-expiring data, as provided by the com.tangosol.net.cache.CacheMap API. When enabled the overflow-scheme will be implemented using com.tangosol.net.cache.OverflowMap, rather then com.tangosol.net.cache.SimpleOverflowMap. Legal values are true or false. Default value is false.

<expiry-delay>

Optional

Specifies the amount of time from last update that entries will be kept by the cache before being expired. Entries that are expired will not be accessible and will be evicted.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of seconds is assumed. A value of zero implies no expiry. Default value is zero.

<autostart>

Optional

The autostart element is intended to be used by cache servers (that is, com.tangosol.net.DefaultCacheServer). It specifies whether 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.



paged-external-scheme

Used in: caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme, near-scheme, versioned-near-scheme, overflow-scheme, read-write-backing-map-scheme, versioned-backing-map-scheme

Description

As with external-scheme, paged-external-schemes define caches which are not JVM heap based, allowing for greater storage capacity. The paged-external-scheme optimizes LRU eviction by using a paging approach (see <paging> subelement). See Chapter 11, "Serialization Paged Cache," for a detailed description of the paged cache functionality.

Implementation

This scheme is implemented by the com.tangosol.net.cache.SerializationPagedCache class.

Paging

Cache entries are maintained over a series of pages, where each page is a separate com.tangosol.io.BinaryStore, obtained from the configured storage manager (see "Pluggable Storage Manager"). When a page is created it is considered to be the "current" page, and all write operations are performed against this page. On a configurable interval (see <page-duration> subelement) the current page is closed and a new current page is created. Read operations for a given key are performed against the last page in which the key was stored. When the number of pages exceeds a configured maximum (see <page-limit> subelement), the oldest page is destroyed and those items which were not updated since the page was closed are be evicted. For example configuring a cache with a duration of ten minutes per page, and a maximum of six pages, will result in entries being cached for at most an hour. Paging improves performance by avoiding individual delete operations against the storage manager as cache entries are removed or evicted. Instead the cache simply releases its references to those entries, and relies on the eventual destruction of an entire page to free the associated storage of all page entries in a single stroke.

Pluggable Storage Manager

External schemes use a pluggable store manager to create and destroy pages, and to access entries within those pages. Supported store-managers include:

Persistence (long-term storage)

Paged external caches are used for temporary storage of large data sets, for example as the back-tier of an overflow-scheme. These caches are not usable as for long-term storage (persistence), and will not survive beyond the life of the JVM. Clustered persistence should be configured by using a read-write-backing-map-scheme on a distributed-scheme. If a non-clustered persistent cache is what is needed, refer to "Persistence (long-term storage)".

Elements

Table D-38 describes the elements you can define within the paged-external-scheme element.

Table D-38 paged-external-scheme Subelements

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. See "Scheme Inheritance" for more information.

<class-name>

Optional

Specifies a custom implementation of the external paged cache. Any custom implementation must extend the com.tangosol.net.cache.SerializationPagedCache class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom external paged cache implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<listener>

Optional

Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache.

<page-limit>

Required

Specifies the maximum number of active pages for the paged cache. Legal values are positive integers between 2 and 3600.

<page-duration>

Optional

Specifies the length of time, in seconds, that a page in the paged cache is current.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of seconds is assumed. Legal values are between 5 and 604800 seconds (one week) and zero (no expiry). Default value is zero

<async-store-manager>

Optional

Configures the paged external cache to use an asynchronous storage manager wrapper for any other storage manager. See "Pluggable Storage Manager" for more information.

<custom-store-manager>

Optional

Configures the paged external cache to use a custom storage manager implementation.

<bdb-store-manager>

Optional

Configures the paged external cache to use Berkeley Database JE on disk databases for cache storage.

<lh-file-manager>

Optional

Configures the paged external cache to use a Coherence LH on disk database for cache storage.

<nio-file-manager>

Optional

Configures the paged external cache to use a memory-mapped file for cache storage.

<nio-memory-manager>

Optional

Configures the paged external cache to use an off JVM heap, memory region for cache storage.



partition-listener

Used in: distributed-scheme

Description

Specifies an implementation of a com.tangosol.net.partition.PartitionListener interface, which allows receiving partition distribution events.

Elements

Table D-39 describes the elements you can define within the partition-listener element.

Table D-39 partition-listener Subelements

Element Required/Optional Description

<class-name>

Required

The name of a class that implements the PartitionListener interface. This implementation must have a zero-parameter public constructor. Default value is the value specified in the partition-listener/class-name parameter in the tangosol-coherence.xml descriptor. See "DistributedCache Service Parameters" for more information.



partitioned

Used in: backing-map-scheme (within a distributed-scheme only)

Description

The partitioned element specifies whether the enclosed backing map is a PartitionAwareBackingMap. (This element is respected only for backing-map-scheme that is a child of a distributed-scheme.) If set to true, the specific scheme contained in the backing-map-scheme element will be used to configure backing maps for each individual partition of the PartitionAwareBackingMap; otherwise it is used for the entire backing map itself.The concrete implementations of the PartitionAwareBackingMap interface are:

Valid values are true or false. Default value is false.


proxy-config

Used in: proxy-scheme.

Description

The proxy-config element specifies the configuration info for the clustered service proxies managed by a proxy service. A service proxy is an intermediary between a remote client (connected to the cluster by using a connection acceptor) and a clustered service used by the remote client.

Elements

Table D-40 describes the elements you can define within the proxy-config element.

Table D-40 proxy-config Subelements

Element Required/Optional Description

<cache-service-proxy>

Optional

Specifies the configuration info for a cache service proxy managed by the proxy service.

<invocation-service-proxy>

Optional

Specifies the configuration info for an invocation service proxy managed by the proxy service.



proxy-scheme

Used in: caching-schemes.

Description

The proxy-scheme element contains the configuration info for a clustered service that allows Coherence*Extend clients to connect to the cluster and use clustered services without having to join the cluster.

Elements

Table D-41 describes the subelements you can define within the proxy-scheme element.

Table D-41 proxy-scheme Subelements

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. See "Scheme Inheritance" for more information.

<service-name>

Optional

Specifies the name of the service.

<serializer>

Optional

Specifies the class configuration info for a com.tangosol.io.Serializer implementation used by the Proxy service to serialize and deserialize user types. For example, the following configures a ConfigurablePofContext that uses the default coherence-pof-types.xml configuration file to write objects to and read from a stream:

<serializer>
  <class-name>com.tangosol.io.pof.ConfigurablePofContext</class-name>
</serializer>

<task-hung-threshold>

Optional

Specifies the amount of time in milliseconds that a task can execute before it is considered "hung". Note: a posted task that has not yet started is never considered as hung. This attribute is applied only if the Thread pool is used (the thread-count value is positive). Legal values are positive integers or zero (indicating no default timeout). Default value is the value specified in the tangosol-coherence.xml descriptor. See the task-hung-threshold parameter in "ProxyService Parameters" for more information.

<task-timeout>

Optional

Specifies the timeout value in milliseconds for requests executing on the service worker threads. This attribute is applied only if the thread pool is used (the thread-count value is positive). If zero is specified, the default service-guardian <timeout-milliseconds> value is used. Legal values are non-negative integers. Default value is the value specified in the tangosol-coherence.xml descriptor. See the task-timeout parameter in "ProxyService Parameters".

<request-timeout>

Optional

Specifies the maximum amount of time a client will wait for a response before abandoning the original request. The request time is measured on the client side as the time elapsed from the moment a request is sent for execution to the corresponding server node(s) and includes the following:

  • the time it takes to deliver the request to an executing node (server)

  • the interval between the time the task is received and placed into a service queue until the execution starts

  • the task execution time

  • the time it takes to deliver a result back to the client

Legal values are positive integers or zero (indicating no default timeout). Default value is the value specified in the tangosol-coherence.xml descriptor. See the request-timeout parameter in "DistributedCache Service Parameters" for more information.

<thread-count>

Optional

Specifies the number of daemon threads used by the service. If zero, all relevant tasks are performed on the service thread. Legal values are positive integers or zero. Default value is the value specified in the thread-count parameter of the tangosol-coherence.xml descriptor. See "ProxyService Parameters" for more information.

<acceptor-config>

Required

Contains the configuration of the connection acceptor used by the service to accept connections from Coherence*Extend clients and to allow them to use the services offered by the cluster without having to join the cluster.

<proxy-config>

Optional

Contains the configuration of the clustered service proxies managed by this service.

<autostart>

Optional

The autostart element is intended to be used by cache servers (that is, com.tangosol.net.DefaultCacheServer). It specifies whether this service should be automatically started at a cluster node. Legal values are true or false. Default value is false.



read-write-backing-map-scheme

Used in: caching-schemes, distributed-scheme.

Description

The read-write-backing-map-scheme defines a backing map which provides a size limited cache of a persistent store. See "Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching" in the Oracle Coherence Getting Started Guide for more details.

Implementation

The read-write-backing-map-scheme is implemented by the com.tangosol.net.cache.ReadWriteBackingMap class.

Cache of an External Store

A read write backing map maintains a cache backed by an external persistent cache store (see <cachestore-scheme> subelement), cache misses will read-through to the back-end store to retrieve the data. If a writable store is provided, cache writes will propagate to the cache store as well.

Refresh-Ahead Caching

When enabled (see <refreshahead-factor> subelement) the cache will watch for recently accessed entries which are about to expire, and asynchronously reload them from the cache store. This insulates the application from potentially slow reads against the cache store, as items periodically expire.

Write-Behind Caching

When enabled (see <write-delay> subelement) the cache will delay writes to the back-end cache store. This allows for the writes to be batched (see <write-batch-factor> subelement) into more efficient update blocks, which occur asynchronously from the client thread.

Elements

The following table describes the elements you can define within the read-write-backing-map-scheme element.

Table D-42 read-write-backing-map-scheme Subelements

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. See "Scheme Inheritance" for more information.

<class-name>

Optional

Specifies a custom implementation of the read write backing map. Any custom implementation must extend the com.tangosol.net.cache.ReadWriteBackingMap class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom read write backing map implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<listener>

Optional

Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache.

<cachestore-scheme>

Optional

Specifies the store to cache. If unspecified the cached data will only reside within the internal cache (see <internal-cache-scheme> subelement), and only reflect operations performed on the cache itself.

<cachestore-timeout>

Optional

Specifies the timeout interval in milliseconds to use for CacheStore read and write operations. If a CacheStore operation times out, the executing thread is interrupted and may ultimately lead to the termination of the cache service.

If zero is specified, the default service-guardian <timeout-milliseconds> value is used.

Legal values are non-negative integers.

<internal-cache-scheme>

Required

Specifies a cache-scheme which will be used to cache entries. Legal values are:

<miss-cache-scheme>

Optional

Specifies a cache-scheme for maintaining information on cache misses. The miss-cache is used track keys which were not found in the cache store. The knowledge that a key is not in the cache store allows some operations to perform faster, as they can avoid querying the potentially slow cache store. A size-limited scheme may be used to control how many misses are cached. If unspecified no cache-miss data will be maintained. Legal values are:

<read-only>

Optional

Specifies if the cache is read only. If true the cache will load data from cachestore for read operations and will not perform any writing to the cachestore when the cache is updated. Legal values are true or false. Default value is false.

<write-delay>

Optional

Specifies the time interval for a write-behind queue to defer asynchronous writes to the cachestore by.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of seconds is assumed. If zero, synchronous writes to the cachestore (without queuing) will take place, otherwise the writes will be asynchronous and deferred by specified time interval after the last update to the value in the cache. Default is zero.

<write-batch-factor>

Optional

The write-batch-factor element is used to calculate the "soft-ripe" time for write-behind queue entries.A queue entry is considered to be "ripe" for a write operation if it has been in the write-behind queue for no less than the write-delay interval. The "soft-ripe" time is the point in time before the actual ripe time after which an entry will be included in a batched asynchronous write operation to the CacheStore (along with all other ripe and soft-ripe entries). In other words, a soft-ripe entry is an entry that has been in the write-behind queue for at least the following duration:

D' = (1.0 - F)*Dwhere:D = write-delay intervalF = write-batch-factor

Conceptually, the write-behind thread uses the following logic when performing a batched update:

  1. The thread waits for a queued entry to become ripe.

  2. When an entry becomes ripe, the thread dequeues all ripe and soft-ripe entries in the queue.

  3. The thread then writes all ripe and soft-ripe entries either by using store() (if there is only the single ripe entry) or storeAll() (if there are multiple ripe/soft-ripe entries).

  4. The thread then repeats (1).

This element is only applicable if asynchronous writes are enabled (that is, the value of the write-delay element is greater than zero) and the CacheStore implements the storeAll() method. The value of the element is expressed as a percentage of the write-delay interval. Legal values are nonnegative doubles less than or equal to 1.0. Default is zero.

<write-requeue-threshold>

Optional

Specifies the maximum size of the write-behind queue for which failed cachestore write operations are requeued. The purpose of this setting is to prevent flooding of the write-behind queue with failed cachestore operations. This can happened in situations where a large number of successive write operations fail. If zero, write-behind requeuing is disabled. Legal values are positive integers or zero. Default is zero.

<refresh-ahead-factor>

Optional

The refresh-ahead-factor element is used to calculate the "soft-expiration" time for cache entries. Soft-expiration is the point in time before the actual expiration after which any access request for an entry will schedule an asynchronous load request for the entry. This attribute is only applicable if the internal cache is a local-scheme, configured with the <expiry-delay> subelement. The value is expressed as a percentage of the internal LocalCache expiration interval. If zero, refresh-ahead scheduling will be disabled. If 1.0, then any get operation will immediately trigger an asynchronous reload. Legal values are nonnegative doubles less than or equal to 1.0. Default value is zero.

<rollback-cachestore-failures>

Optional

Specifies whether exceptions caught during synchronous cachestore operations are rethrown to the calling thread (possibly over the network to a remote member). If the value of this element is false, an exception caught during a synchronous cachestore operation is logged locally and the internal cache is updated. If the value is true, the exception is rethrown to the calling thread and the internal cache is not changed. If the operation was called within a transactional context, this would have the effect of rolling back the current transaction. Legal values are true or false. Default value is false.



remote-cache-scheme

Used in: cachestore-scheme, caching-schemes, near-scheme.

Description

The remote-cache-scheme element contains the configuration info necessary to use a clustered cache from outside the cluster by using Coherence*Extend.

Elements

The following table describes the elements you can define within the remote-cache-scheme element.

Table D-43 remote-cache-scheme Subelements

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. See "Scheme Inheritance" for more information.

<service-name>

Optional

Specifies the name of the service which will manage caches created from this scheme.

<operation-bundling>

Optional

Specifies the configuration info for a bundling strategy.

<initiator-config>

Required

Contains the configuration of the connection initiator used by the service to establish a connection with the cluster.



remote-invocation-scheme

Used in: caching-schemes

Description

The remote-invocation-scheme element contains the configuration info necessary to execute tasks within the context of a cluster without having to first join the cluster. This scheme uses Coherence*Extend to connect to the cluster.

Elements

Table D-44 describes the elements you can define within the remote-invocation-scheme element.

Table D-44 remote-invocation-scheme Subelements

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. See "Scheme Inheritance" for more information.

<service-name>

Optional

Specifies the name of the service.

<initiator-config>

Required

Contains the configuration of the connection initiator used by the service to establish a connection with the cluster.



replicated-scheme

Used in: caching-schemes, near-scheme, versioned-near-scheme, overflow-scheme, versioned-backing-map-scheme

Description

The replicated scheme defines caches which fully replicate all their cache entries on each cluster nodes running the specified service. See "Replicated Cache Service" for a more detailed description of replicated caches.

Clustered Concurrency Control

Replicated caches support cluster wide key-based locking so that data can be modified in a cluster without encountering the classic missing update problem. Note that any operation made without holding an explicit lock is still atomic but there is no guarantee that the value stored in the cache does not change between atomic operations.

Cache Storage (Backing Map)

Storage for the cache is specified by using the backing-map scheme (see <backing-map> subelement). For instance, a replicated cache which uses a local-scheme for its backing map will result in cache entries being stored in-memory.

Elements

Table D-45 describes the elements you can define within the replicated-scheme element.

Table D-45 replicated-scheme Subelements

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. See "Scheme Inheritance" for more information.

<service-name>

Optional

Specifies the name of the service which will manage caches created from this scheme. Services are configured from within the <services> element in the tangosol-coherence.xml file. See Appendix H, "Operational Configuration Elements" for more information.

<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:

To ensure cache coherence, the backing-map of an replicated 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.

<standard-lease-milliseconds>

Optional

Specifies the duration of the standard lease in milliseconds. When a lease has aged past this number of milliseconds, the lock will automatically be released. Set this value to zero to specify a lease that never expires. The purpose of this setting is to avoid deadlocks or blocks caused by stuck threads; the value should be set higher than the longest expected lock duration (for example, higher than a transaction timeout). It's also recommended to set this value higher than packet-delivery/timeout-milliseconds value. Legal values are from positive long numbers or zero. Default value is the value specified for packet-delivery/timeout-milliseconds in the tangosol-coherence.xml descriptor. See "ReplicatedCache Service Parameters" for more information.

<lease-granularity>

Optional

Specifies the lease ownership granularity. Available since release 2.3.Legal values are:

  • thread

  • member

A value of thread means that locks are held by a thread that obtained them and can only be released by that thread. A value of member means that locks are held by a cluster node and any thread running on the cluster node that obtained the lock can release it. Default value is the lease-granularity value specified in the tangosol-coherence.xml descriptor. See "ReplicatedCache Service Parameters" for more information.

<mobile-issues>

Optional

Specifies whether the lease issues should be transferred to the most recent lock holders. Legal values are true or false. Default value is the mobile-issue value specified in the tangosol-coherence.xml descriptor. See "ReplicatedCache Service Parameters" for more information.

<autostart>

Optional

The autostart element is intended to be used by cache servers (that is, com.tangosol.net.DefaultCacheServer). It specifies whether 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.



tcp-acceptor

Used in: acceptor-config.

Description

The tcp-acceptor element specifies the configuration info for a connection acceptor that accepts connections from Coherence*Extend clients over TCP/IP. For additional details and example configurations see Chapter 17, "Configuring and Using Coherence*Extend."

Elements

Table D-46 describes the elements you can define within the tcp-acceptor element.

Table D-46 tcp-acceptor Subelements

Element Required/Optional Description

<local-address>

Required

Specifies the local address (IP or DNS name) and port that the TCP/IP ServerSocket opened by the connection acceptor will listen on.For example, the following will instruct the connection acceptor to bind the TCP/IP ServerSocket to 192.168.0.2:9099:

<local-address>
  <address>192.168.0.2</address>
  <port>9099</port>
  <reusable>true</reusable>
</local-address>

The <reusable> child element specifies whether a TCP/IP socket can be bound to an address if a previous connection is in a timeout state. When a TCP/IP connection is closed the connection may remain in a timeout state for a period after the connection is closed (typically known as the TIME_WAIT state or 2MSL wait state). For applications using a well known socket address or port it may not be possible to bind a socket to a required address if there is a connection in the timeout state involving the socket address or port.

<keep-alive-enabled>

Optional

Indicates whether keep alive (SO_KEEPALIVE) is enabled on a TCP/IP socket. Valid values are true and false. Keep alive is enabled by default.

<tcp-delay-enabled>

Optional

Indicates whether TCP delay (Nagle's algorithm) is enabled on a TCP/IP socket. Valid values are true and false. TCP delay is disabled by default.

<receive-buffer-size>

Optional

Configures the size of the underlying TCP/IP socket network receive buffer.Increasing the receive buffer size can increase the performance of network I/O for high-volume connections, while decreasing it can help reduce the backlog of incoming data.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of one is assumed. Default value is O/S dependent.

<send-buffer-size>

Optional

Configures the size of the underlying TCP/IP socket network send buffer.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of one is assumed. Default value is O/S dependent.

<listen-backlog>

Optional

Configures the size of the TCP/IP server socket backlog queue. Valid values are positive integers. Default value is O/S dependent.

<linger-timeout>

Optional

Enables SO_LINGER on a TCP/IP socket with the specified linger time.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of milliseconds is assumed. Linger is disabled by default.

<authorized-hosts>

Optional

A collection of IP addresses of TCP/IP initiator hosts that are allowed to connect to this TCP/IP acceptor.



tcp-initiator

Used in: initiator-config.

Description

The tcp-initiator element specifies the configuration info for a connection initiator that enables Coherence*Extend clients to connect to a remote cluster by using TCP/IP. For additional details and example configurations see Chapter 17, "Configuring and Using Coherence*Extend."

Elements

Table D-47 describes the elements you can define within the tcp-initiator element.

Table D-47 tcp-initiator Subelements

Element Required/Optional Description

<local-address>

Optional

Specifies the local address (IP or DNS name) that the TCP/IP socket opened by the connection initiator will be bound to. For example, the following will instruct the connection initiator to bind the TCP/IP socket to the IP address 192.168.0.1:

<local-address>
  <address>192.168.0.1</address>
</local-address>

<remote-addresses>

Required

Contains the <socket-address> of one or more TCP/IP connection acceptors. The TCP/IP connection initiator uses this information to establish a TCP/IP connection with a remote cluster. The TCP/IP connection initiator will attempt to connect to the addresses in a random order, until either the list is exhausted or a TCP/IP connection is established.For example, the following will instruct the connection initiator to attempt to connect to 192.168.0.2:9099 and 192.168.0.3:9099 in a random order:

<remote-addresses>
  <socket-address>
    <address>192.168.0.2</address>
    <port>9099</port>
  </socket-address>
  <socket-address>
    <address>192.168.0.3</address>
    <port>9099</port>
  </socket-address>
</remote-addresses>

Alternatively, the set of remote addresses may be specified using a <address-provider> element instead of the list of <socket-address> elements. This approach may be used to implement custom load balancing algorithms and/or dynamic discovery of TCP/IP connection acceptors.

<keep-alive-enabled>

Optional

Indicates whether keep alive (SO_KEEPALIVE) is enabled on a TCP/IP socket. Valid values are true and false. Keep alive is enabled by default.

<tcp-delay-enabled>

Optional

Indicates whether TCP delay (Nagle's algorithm) is enabled on a TCP/IP socket. Valid values are true and false. TCP delay is disabled by default.

<receive-buffer-size>

Optional

Configures the size of the underlying TCP/IP socket network receive buffer.Increasing the receive buffer size can increase the performance of network I/O for high-volume connections, while decreasing it can help reduce the backlog of incoming data.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of one is assumed. Default value is O/S dependent.

<send-buffer-size>

Optional

Configures the size of the underlying TCP/IP socket network send buffer.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[K|k|M|m|G|g]?[B|b]?

where the first non-digit (from left to right) indicates the factor with which the preceding decimal value should be multiplied:

  • K or k (kilo, 210)

  • M or m (mega, 220)

  • G or g (giga, 230)

If the value does not contain a factor, a factor of one is assumed. Default value is O/S dependent.

<connect-timeout>

Optional

Specifies the maximum amount of time to wait while establishing a connection with a connection acceptor.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of milliseconds is assumed. Default value is an infinite timeout.

<linger-timeout>

Optional

Enables SO_LINGER on a TCP/IP socket with the specified linger time.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of milliseconds is assumed. Linger is disabled by default.



version-persistent-scheme

Used in: versioned-backing-map-scheme.

Description

The version-persistent-scheme defines a cache for storing object versioning information in a clustered cache. Specifying a size limit on the specified scheme's backing-map allows control over how many version identifiers are tracked.

Elements

Table D-48 describes the elements you can define within the version-persistent-scheme element.

Table D-48 persistent-scheme Subelements

Element Required/Optional Description

<cache-name-suffix>

Optional

Specifies the name modifier that is used to create a cache of version objects associated with a given cache. The value of this element is appended to the base cache name. Legal value is a string. Default value is -persist. For example, if the base case is named Sessions and this name modifier is set to -persist, the associated version cache will be named Sessions-persist.

<replicated-scheme> or <distributed-scheme>

Required

Specifies the scheme for the cache used to maintain the versioning information. Legal values are:



version-transient-scheme

Used in: versioned-near-scheme, versioned-backing-map-scheme.

Description

The version-transient-scheme defines a cache for storing object versioning information for use in versioned near-caches. Specifying a size limit on the specified scheme's backing-map allows control over how many version identifiers are tracked.

Elements

The following table describes the elements you can define within the version-transient-scheme element.

Table D-49 transient-scheme Subelements

Element Required/Optional Description

<cache-name-suffix>

Optional

Specifies the name modifier that is used to create a cache of version objects associated with a given cache. The value of this element is appended to the base cache name. Legal value is a string. Default value is "-version". For example, if the base case is named Sessions and this name modifier is set to -version, the associated version cache will be named Sessions-version.

<replicated-scheme> or <distributed-scheme>

Required

Specifies the scheme for the cache used to maintain the versioning information. Legal values are:



versioned-backing-map-scheme

Used in: caching-schemes, distributed-scheme, replicated-scheme, optimistic-scheme.

Description

The versioned-backing-map-scheme is an extension of a read-write-backing-map-scheme, defining a size limited cache of a persistent store. It uses object versioning to determine what updates need to be written to the persistent store. See "Versioning" for more information.

Implementation

The versioned-backing-map-scheme scheme is implemented by the com.tangosol.net.cache.VersionedBackingMap class.

Cache of an External Store

As with the read-write-backing-map-scheme, a versioned backing map maintains a cache backed by an external persistent cache store (see <cachestore-scheme> subelement), cache misses will read-through to the back-end store to retrieve the data. Cache stores may also support updates to the back-end data store.

Refresh-Ahead and Write-Behind Caching

As with the read-write-backing-map-scheme both the refresh-ahead (see <refresh-ahead> subelement) and write-behind (see <write-behind> subelement) caching optimizations are supported. See "Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching" in the Oracle Coherence Getting Started Guide for more details.

Versioning

For entries whose values implement the com.tangosol.util.Versionable interface, the versioned backing map will use the version identifier to determine if an update must be written to the persistent store. The primary benefit of this feature is that in the event of cluster node failover, the backup node can determine if the most recent version of an entry has already been written to the persistent store, and if so it can avoid an extraneous write.

Elements

Table D-50 describes the elements you can define within the versioned-backing-map-scheme element.

Table D-50 versioned-backing-map-scheme Subelement

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. See "Scheme Inheritance" for more information.

<class-name>

Optional

Specifies a custom implementation of the versioned backing map. Any custom implementation must extend the com.tangosol.net.cache.VersionedBackingMap class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom versioned backing map implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<listener>

Optional

Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache.

<cachestore-scheme>

Optional

Specifies the store to cache. If unspecified the cached data will only reside within the (see <internal-cache-scheme> subelement), and only reflect operations performed on the cache itself.

<internal-cache-scheme>

Required

Specifies a cache-scheme which will be used to cache entries. Legal values are:

<miss-cache-scheme>

Optional

Specifies a cache-scheme for maintaining information on cache misses. The miss-cache is used track keys which were not found in the cache store. The knowledge that a key is not in the cache store allows some operations to perform faster, as they can avoid querying the potentially slow cache store. A size-limited scheme may be used to control how many misses are cached. If unspecified no cache-miss data will be maintained. Legal values are:

<read-only>

Optional

Specifies if the cache is read only. If true the cache will load data from cachestore for read operations and will not perform any writing to the cachestore when the cache is updated. Legal values are true or false. Default value is false.

<write-delay>

Optional

Specifies the time interval for a write-behind queue to defer asynchronous writes to the cachestore by.The value of this element must be in the following format:

[\d]+[[.][\d]+]?[MS|ms|S|s|M|m|H|h|D|d]?

where the first non-digits (from left to right) indicate the unit of time duration:

  • MS or ms (milliseconds)

  • S or s (seconds)

  • M or m (minutes)

  • H or h (hours)

  • D or d (days)

If the value does not contain a unit, a unit of seconds is assumed. If zero, synchronous writes to the cachestore (without queuing) will take place, otherwise the writes will be asynchronous and deferred by the number of seconds after the last update to the value in the cache. Default is zero.

<write-batch-factor>

Optional

The write-batch-factor element is used to calculate the "soft-ripe" time for write-behind queue entries. A queue entry is considered to be "ripe" for a write operation if it has been in the write-behind queue for no less than the write-delay interval. The "soft-ripe" time is the point in time before the actual "ripe" time after which an entry will be included in a batched asynchronous write operation to the CacheStore (along with all other "ripe" and "soft-ripe" entries). This element is only applicable if asynchronous writes are enabled (that is, the value of the write-delay element is greater than zero) and the CacheStore implements the storeAll() method. The value of the element is expressed as a percentage of the write-delay interval. For example, if the value is zero, only "ripe" entries from the write-behind queue will be batched. On the other hand, if the value is 1.0, all currently queued entries will be batched and the value of the write-delay element will be effectively ignored. Legal values are nonnegative doubles less than or equal to 1.0. Default is zero.

<write-requeue-threshold>

Optional

Specifies the maximum size of the write-behind queue for which failed cachestore write operations are requeued. The purpose of this setting is to prevent flooding of the write-behind queue with failed cachestore operations. This can happened in situations where a large number of successive write operations fail. If zero, write-behind requeuing is disabled. Legal values are positive integers or zero. Default is zero.

<refresh-ahead-factor>

Optional

The refresh-ahead-factor element is used to calculate the "soft-expiration" time for cache entries. Soft-expiration is the point in time before the actual expiration after which any access request for an entry will schedule an asynchronous load request for the entry. This attribute is only applicable if the internal cache (see <internal-cache-scheme> subelement) is a local-scheme, configured with the <location> subelement. The value is expressed as a percentage of the internal LocalCache expiration interval. If zero, refresh-ahead scheduling will be disabled. If 1.0, then any get operation will immediately trigger an asynchronous reload. Legal values are nonnegative doubles less than or equal to 1.0. Default value is zero.

<rollback-cachestore-failures>

Optional

Specifies whether exceptions caught during synchronous cachestore operations are rethrown to the calling thread (possibly over the network to a remote member). If the value of this element is false, an exception caught during a synchronous cachestore operation is logged locally and the internal cache is updated. If the value is true, the exception is rethrown to the calling thread and the internal cache is not changed. If the operation was called within a transactional context, this would have the effect of rolling back the current transaction. Legal values are true or false. Default value is false.

<version-persistent-scheme>

Optional

Specifies a cache-scheme for tracking the version identifier for entries in the persistent cachestore (see cachestore-scheme).

<version-transient-scheme>

Optional

Specifies a cache-scheme for tracking the version identifier for entries in the transient internal cache (see <internal-cache-scheme> subelement).

<manage-transient>

Optional

Specifies if the backing map is responsible for keeping the transient version cache up to date. If disabled the backing map manages the transient version cache only for operations for which no other party is aware (such as entry expiry). This is used when there is already a transient version cache of the same name being maintained at a higher level, for instance within a versioned-near-scheme. Legal values are true or false. Default value is false.



versioned-near-scheme

Used in: caching-schemes.

Note:

As of Coherence release 2.3, it is suggested that a near-scheme be used instead of versioned-near-scheme. Legacy Coherence applications use versioned-near-scheme to ensure Coherence through object versioning. As of Coherence 2.3 the near-scheme includes a better alternative, in the form of reliable and efficient front cache invalidation.

Description

As with the near-scheme, the versioned-near-scheme defines a two tier cache consisting of a small and fast front-end, and higher-capacity but slower back-end cache. The front-end (see <front-end> subelement) and back-end (see <back-end> subelement) are expressed as normal cache-schemes. A typical deployment might use a local-scheme for the front-end, and a distributed-scheme for the back-end. See Appendix B, "Types of Caches in Coherence" for a more detailed description of versioned near caches.

Implementation

The versioned near scheme is implemented by the com.tangosol.net.cache.VersionedNearCache class.

Versioning

Object versioning is used to ensure coherence between the front and back tiers. See the <version-transient-scheme> subelement for more information

Elements

Table D-51 describes the elements you can define within the near-scheme element.

Table D-51 near-scheme Subelements

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. See "Scheme Inheritance" for more information.

<class-name>

Optional

Specifies a custom implementation of the versioned near cache. The specified class must extend the com.tangosol.net.cache.VersionedNearCache class and declare the exact same set of public constructors.

<init-params>

Optional

Specifies initialization parameters, for use in custom versioned near cache implementations which implement the com.tangosol.run.xml.XmlConfigurable interface.

<listener>

Optional

Specifies an implementation of a com.tangosol.util.MapListener which will be notified of events occurring on the cache.

<front-scheme>

Required

Specifies the cache-scheme to use in creating the front-tier cache.Legal values are:

For example:

<front-scheme>
  <local-scheme>
    <scheme-ref>default-eviction</scheme-ref>
  </local-scheme>
</front-scheme>

or

<front-scheme>
  <class-scheme>
    <class-name>com.tangosol.util.SafeHashMap</class-name>
    <init-params></init-params>
  </class-scheme>
</front-scheme>

<back-scheme>

Required

Specifies the cache-scheme to use in creating the back-tier cache.Legal values are:

For Example:

<back-scheme>
  <distributed-scheme>
    <scheme-ref>default-distributed</scheme-ref>
  </distributed-scheme>
</back-scheme>

<version-transient-scheme>

Optional

Specifies a scheme for versioning cache entries, which ensures coherence between the front and back tiers.

<autostart>

Optional

The autostart element is intended to be used by cache servers (that is, com.tangosol.net.DefaultCacheServer). It specifies whether 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.