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<document>
  <properties>
    <title>Configuring the Local Cache</title>
    <author email="pete@kazmier.com">Pete Kazmier</author>
    <author email="ASmuts@therealm.com">Aaron Smuts</author>
  </properties>

  <body>
    <section name="Configuring the Local Cache">
      <p>
        This document is intended to provide various answers to
        questions regarding the configuration of a local cache.  The
        document is presented in a question / answer format.
      </p>
      <subsection name="Where is the configuration information?">
        <p>
          Configuration of local caches involves editing the cache
          configuration file, named <code>cache.ccf</code>.  The
          classpath should include the directory where this file is
          located or the file should be placed at the root of the
          classpath, since it is discovered automatically.
        </p>
      </subsection>
      <subsection name="What is in the cache.ccf file?">
        <p>
          The <code>cache.ccf</code> file contains default configuration
          information for cache regions and specific configuration
          information for regions that you predefine.  Regions not using
          default behaviors should generally be configured via the
          <code>cache.ccf</code> file.  If you can put configuration
          information in a class, you can edit a props file just as
          easily.  This makes modification of the regional setting more
          efficient and allows for startup error checking.
        </p>
        <p>
          There are three main sections of the <code>cache.ccf</code>
          file:
        </p>
        <ul>
          <li> the default and system settings </li>
          <li> the region specific settings </li>
          <li> the auxiliary cache definitions </li>
        </ul>
      </subsection>
      <subsection name="How do I set up default values for regions?">
        <p>
          You can establish default values that any non-preconfigured
          region will inherit.  The non-predefined region will be
          created when you call
          <code>CacheAccess.getAccess("cacheName")</code>.  The default
          setting look like this:
        </p>
        <source><![CDATA[
# DEFAULT CACHE REGION

# sets the default aux value for any non configured caches
jcs.default=DC,RFailover
jcs.default.cacheattributes=
    org.apache.commons.jcs.engine.CompositeCacheAttributes
jcs.default.cacheattributes.MaxObjects=1000
        ]]></source>
        <p>
          The most important line is
          <code>jcs.default=DC,Rfailover</code>. This tells the cache
          what auxiliary caches should be used.  Auxiliary caches are
          configured in the third section of the <code>cache.ccf</code>
          and are referenced in a comma separated list.  You can add as
          many auxiliary caches as you want, but the behavior of remote
          and lateral auxiliaries may conflict.  This allows you to
          define different configurations for auxiliary caches and to
          use these different configurations for different regions.
        </p>
      </subsection>
      <subsection name="How do I define a region?">
        <p>
          Defining a region involves specifying which auxiliary caches
          it will use and how many objects it will store in memory.  A
          typical region definition looks like:
        </p>
        <source><![CDATA[
jcs.region.testCache=DC,RFailover
jcs.region.testCache.cacheattributes=
    org.apache.commons.jcs.engine.CompositeCacheAttributes
jcs.region.testCache.cacheattributes.MaxObjects=1000
        ]]></source>
        <p>
          The region name is <code>testCache</code>.  It will have a
          1000 item memory limit and will use the DC and RFailover
          auxiliary caches.  If a typical element for this region was
          very large, you might want to lower the number of items stored
          in memory.  The size of the memory storage is dependent on the
          priority of the cache, the size of its elements, and the
          amount of RAM on the machine.
        </p>
      </subsection>
      <subsection name="How do I configure an auxiliary cache?">
        <p>
          Each auxiliary cache is created through a factory that passes
          an attribute object to the constructor.  The attributes are
          set via reflection and should be fairly simple to understand.
          Each auxiliary cache will be fully documented.  Plugging in
          your own auxiliary cache become a simple matter given the
          reflexive manner of initialization.
        </p>
        <p>
          The most important settings for common usage are the disk path
          and the remote cache location.  It is recommended that only
          disk and remote auxiliaries be used.  The lateral caches are
          functional but not as efficient.
        </p>
        <p>
          The default configuration code above specifies that
          non-preconfigured caches use the auxiliary cache by the name
          DC.  This cache is defined in the third section of the file:
        </p>
        <source><![CDATA[
jcs.auxiliary.DC=
    org.apache.commons.jcs.auxiliary.disk.DiskCacheFactory
jcs.auxiliary.DC.attributes=
    org.apache.commons.jcs.auxiliary.disk.DiskCacheAttributes
jcs.auxiliary.DC.attributes.DiskPath=c:/dev/cache/raf
        ]]></source>
        <p>
          The only thing that needs to be set here is the
          <code>DiskPath</code> value.  Change it to wherever you want
          the cache to persist unused items.
        </p>
        <p>
          The default region is also set to use an auxiliary called
          <code>RFailover</code>.  This is a remote cache that is
          designed to failover to other remote servers in a cluster:
        </p>
        <source><![CDATA[
jcs.auxiliary.RFailover=
    org.apache.commons.jcs.auxiliary.remote.RemoteCacheFactory
jcs.auxiliary.RFailover.attributes=
    org.apache.commons.jcs.auxiliary.remote.RemoteCacheAttributes
jcs.auxiliary.RFailover.attributes.RemoteTypeName=LOCAL
jcs.auxiliary.RFailover.attributes.FailoverServers=
    localhost:1102,localhost:1101
        ]]></source>
        <p>
          If you don't have more than one remote server running, just
          specify it by itself in the <code>FailoverServers</code>
          attribute.
        </p>
      </subsection>
    </section>
  </body>
</document>