B Session Cache Configuration File

Coherence*Web uses the caches and services defined in the session-cache-config.xml file to implement HTTP session management. This file is deployed under WEB-INF/classes in either the instrumented Web application or shared WebLogic Coherence*Web SPI library. Table B-1 describes the default cache-related values used in the session-cache-config.xml file.

Table B-1 Cache-Related Values used in session-cache-config.xml

Value Description

session-management

This cache is used to store internal configuration and management information for the session management implementation. This information is updated infrequently; therefore, it is a replicated cache by default.

servletcontext-storage

If ServletContext attribute clustering (see the coherence-servletcontext-clustered parameter in Table A-1) is enabled (it is disabled by default), this cache is used to store ServletContext attributes. This cache is replicated by default, as it is expected that there will a few read-mostly attributes.

session-storage

This cache is used to store session models. By default it is mapped to a near cache backed by a distributed cache since it is expected that a container will access and modify a subset of sessions multiple times (assuming that sticky session load balancing is configured.) See "Session Models" for more information on session models.

session-overflow

If the coherence-sessioncollection-class parameter (described in Table A-1) is set to com.tangosol.coherence.servlet.SplitHttpSessionCollection, then this cache will hold "large" session attributes. By default, session attributes larger than 1K will be stored in this cache. This is configured as a distributed cache.

session-death-certificates

Recently expired session IDs are stored in this cache to prevent reuse of a recently used session ID. By default, each storage node will hold up to 4000 session IDs, and session IDs will be evicted after 24 hours. This is configured as a distributed cache.

local-session-storage

This local cache is used to store session models that are considered to be "local" by the configured (if any) coherence-distributioncontroller-class parameter. This parameter is described in Table A-1.

local-attribute-storage

This local cache is used to store attributes that are not distributed. This can happen under two conditions:

  • A coherence-distributioncontroller-class is configured. Attributes for "local" sessions will be stored in this cache.

  • A non-serializable attribute is set on a distributed session. If coherence-sticky-sessions and coherence-preserve-attributes are set to true, then this attribute will be placed in this cache. These parameters are described in Table A-1.

Table B-2 describes the services-related values used in the session-cache-config.xml file.

Table B-2 Services-Related Values used in session-cache-config.xml

Value Description

ReplicatedSessionsMisc

This replicated service is used by the session-management and servletcontext-storage caches.

DistributedSessions

This distributed service is used by the following caches:

  • session-storage

  • session-overflow

  • session-death-certificates

The tangosol.coherence.session.localstorage system property controls whether a JVM will store and manage data for these caches. Under most circumstances, this should be set to false for Web container JVMs. See "Deployment Topologies" for more details.

SessionOwnership

This invocation service is used by the sticky session optimization feature (if coherence-sticky-sessions is set to true).

Example B-1 illustrates the contents of the session-cache-config.xml file. The cache- and services-related values described in the previous tables appear in bold.

Example B-1 Contents of the session-cache-config.xml File

<?xml version="1.0"?>
<!DOCTYPE cache-config SYSTEM "cache-config.dtd">
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
<!--                                                                       -->
<!--      Cache configuration descriptor for Coherence*Web                 -->
<!--                                                                       -->
<!-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -->
<cache-config>
  <caching-scheme-mapping>
    <!--
    The clustered cache used to store Session management data.
    -->
    <cache-mapping>
      <cache-name>session-management</cache-name>
      <scheme-name>replicated</scheme-name>
    </cache-mapping>

    <!--
    The clustered cache used to store ServletContext attributes.
    -->
    <cache-mapping>
      <cache-name>servletcontext-storage</cache-name>
      <scheme-name>replicated</scheme-name>
    </cache-mapping>

    <!--
    The clustered cache used to store Session attributes.
    -->
    <cache-mapping>
      <cache-name>session-storage</cache-name>
      <scheme-name>session-near</scheme-name>
    </cache-mapping>

    <!--
    The clustered cache used to store the "overflowing" (split-out due to size)
    Session attributes. Only used for the "Split" model.
    -->
    <cache-mapping>
      <cache-name>session-overflow</cache-name>
      <scheme-name>session-distributed</scheme-name>
    </cache-mapping>

    <!--
    The clustered cache used to store IDs of "recently departed" Sessions.
    -->
    <cache-mapping>
      <cache-name>session-death-certificates</cache-name>
      <scheme-name>session-certificate</scheme-name>
    </cache-mapping>

    <!--
    The local cache used to store Sessions that are not yet distributed (if
    there is a distribution controller).
    -->
    <cache-mapping>
      <cache-name>local-session-storage</cache-name>
      <scheme-name>unlimited-local</scheme-name>
    </cache-mapping>

    <!--
    The local cache used to store Session attributes that are not distributed
    (if there is a distribution controller or attributes are allowed to become
    local when serialization fails).
    -->
    <cache-mapping>
      <cache-name>local-attribute-storage</cache-name>
      <scheme-name>unlimited-local</scheme-name>
    </cache-mapping>
  </caching-scheme-mapping>

  <caching-schemes>
    <!--
    Replicated caching scheme used by the Session management and ServletContext
    attribute caches.
    -->
    <replicated-scheme>
      <scheme-name>replicated</scheme-name>
      <service-name>ReplicatedSessionsMisc</service-name>
      <backing-map-scheme>
        <local-scheme>
          <scheme-ref>unlimited-local</scheme-ref>
        </local-scheme>
      </backing-map-scheme>
      <request-timeout>30s</request-timeout>
      <autostart>true</autostart>
    </replicated-scheme>

    <!--
    Near caching scheme used by the Session attribute cache. The front cache
    uses a Local caching scheme and the back cache uses a Distributed caching
    scheme.
    -->
    <near-scheme>
      <scheme-name>session-near</scheme-name>
      <front-scheme>
        <local-scheme>
          <scheme-ref>session-front</scheme-ref>
        </local-scheme>
      </front-scheme>
      <back-scheme>
        <distributed-scheme>
          <scheme-ref>session-distributed</scheme-ref>
        </distributed-scheme>
      </back-scheme>
      <invalidation-strategy>present</invalidation-strategy>
    </near-scheme>

    <local-scheme>
      <scheme-name>session-front</scheme-name>
      <eviction-policy>HYBRID</eviction-policy>
      <high-units>1000</high-units>
      <low-units>750</low-units>
    </local-scheme>

    <distributed-scheme>
      <scheme-name>session-distributed</scheme-name>
      <scheme-ref>session-base</scheme-ref>
      <backing-map-scheme>
        <local-scheme>
          <scheme-ref>unlimited-local</scheme-ref>
        </local-scheme>
        <!-- for disk overflow use this backing scheme instead:
        <overflow-scheme>
          <scheme-ref>session-paging</scheme-ref>
        </overflow-scheme>
        -->
      </backing-map-scheme>
    </distributed-scheme>

    <!--
    Distributed caching scheme used by the "recently departed" Session cache.
    -->
    <distributed-scheme>
      <scheme-name>session-certificate</scheme-name>
      <scheme-ref>session-base</scheme-ref>
      <backing-map-scheme>
        <local-scheme>
          <eviction-policy>HYBRID</eviction-policy>
          <high-units>4000</high-units>
          <low-units>3000</low-units>
          <expiry-delay>86400</expiry-delay>
        </local-scheme>
      </backing-map-scheme>
    </distributed-scheme>

    <!--
    "Base" Distributed caching scheme that defines common configuration.
    -->
    <distributed-scheme>
      <scheme-name>session-base</scheme-name>
      <service-name>DistributedSessions</service-name>
      <thread-count>0</thread-count>
      <lease-granularity>member</lease-granularity>
      <local-storage system-property="tangosol.coherence.session.localstorage">false</local-storage>
      <partition-count>257</partition-count>
      <backup-count>1</backup-count>
      <backup-storage>
        <type>on-heap</type>
      </backup-storage>
      <backing-map-scheme>
        <local-scheme>
          <scheme-ref>unlimited-local</scheme-ref>
        </local-scheme>
      </backing-map-scheme>
      <request-timeout>30s</request-timeout>
      <autostart>true</autostart>
    </distributed-scheme>

    <!--
    Disk-based Session attribute overflow caching scheme.
    -->
    <overflow-scheme>
      <scheme-name>session-paging</scheme-name>
      <front-scheme>
        <local-scheme>
          <scheme-ref>session-front</scheme-ref>
        </local-scheme>
      </front-scheme>
      <back-scheme>
        <external-scheme>
          <bdb-store-manager/>
        </external-scheme>
      </back-scheme>
    </overflow-scheme>

    <!--
    Local caching scheme definition used by all caches that do not require an
    eviction policy.
    -->
    <local-scheme>
      <scheme-name>unlimited-local</scheme-name>
      <service-name>LocalSessionCache</service-name>
    </local-scheme>

    <!--
    Clustered invocation service that manages sticky session ownership.
    -->
    <invocation-scheme>
      <service-name>SessionOwnership</service-name>
      <request-timeout>30s</request-timeout>
    </invocation-scheme>
  </caching-schemes>
</cache-config>