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<document>
	<properties>
		<title>Getting Started -- Intoduction</title>
		<author email="asmuts@apache.org">Aaron Smuts</author>
	</properties>

	<body>

		<section name="Getting Started">
			<p>
				To start using JCS you need to (1) understand the core
				concepts, (2) download JCS, (3) get the required
				dependencies, (4) configure JCS, and (5) then start
				programming to it. The purpose of the getting started
				guide is to help you get up and running with JCS as
				quickly as possible. In depth doumentation on the
				various features of JCS is provided in the User's Guide.
			</p>
		</section>

		<section name="STEP 1: Understand the Core Concepts">
			<p>
				In order to use JCS, you must understand a few core
				concepts, most importantly you need to know the
				difference between "elements," "regions," and
				"auxiliaries".
			</p>
			<p>
				JCS is an object cache. You can put objects, or
				"elements," into JCS and reference them via a key, much
				like a hashtable.
			</p>
			<p>
				You can think of JCS as a collection of hashtables that
				you reference by name. Each of these hashtables is
				called a "region," and each region can be configured
				independently of the others. For instance, I may have a
				region called Cities where I cache City objects that
				change infrequently. I may also define a region called
				Products where I cache product data that changes more
				frequently. I would configure the volatile Product
				region to expire elements more quickly than the City
				region.
			</p>
			<p>
				"Auxiliaries" are optional plugins that a region can
				use. The core auxiliaries are the Indexed Disk Cache,
				the TCP Lateral Cache, and the Remote Cache Server. The
				Disk Cache, for example, allows you to swap items onto
				disk when a memory threshold is reached. You can read
				more about the available auxiliaries
				<a href="../Plugins.html">HERE</a>
				.
			</p>
		</section>


		<section name="STEP 2: Download JCS">
			<p>
				Download the latest version of JCS. The latest JCS
				builds are located
				<a
					href="http://svn.apache.org/viewcvs.cgi/jakarta/jcs/trunk/tempbuild/">
					HERE
				</a>
			</p>
			<p>
				If you would like to build JCS yourself, check it out
				from Subversion and build it as you would any other
				project built by Maven 1.x. The location of the
				repository is documented in the project info pages that
				are linked via the left nav.
			</p>
		</section>

		<section name="STEP 3: Get the Required Dependencies">
			<p>
				As of version 1.2.7.0, the core of JCS (the LRU memory
				cache, the indexed disk cache, the TCP lateral, and the
				RMI remote server) requires only two other jars.
			</p>
			<p>
				<a
					href="http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html">
					concurrent
				</a>
			</p>
			<p>commons-logging</p>
			<p>
				Versions 1.2.6.9 and below also require the following
				two additional jars:
			</p>
			<p>commons-collections</p>
			<p>commons-lang</p>
			<p>
				All of the other dependencies listed on the project info
				page are for optional plugins.
			</p>
		</section>

		<section name="STEP 4: Configure JCS">
			<p>
				JCS is configured from a properties file called
				"cache.ccf". There are alternatives to using this file,
				but they are beyond the scope of the getting started
				guide.
			</p>
			<p>
				The cache configuration has three parts: default,
				regions, and auxiliaries. You can think of the
				auxiliaries as log4j appenders and the regions as log4j
				categories. For each region (or category) you can
				specify and auxiliary (or appender to use). If you don't
				define a region in the cache.ccf, then the default
				settings are used. The difference between JCS and log4j
				is that in JCS, pre-defined regions do not inherent
				auxiliaries from the default region.
			</p>
			<p>
				The following cache.ccf file defines one region called
				"testCache1" and uses the Indexed Disk Cache, here
				called "DC" by default. The LRU Memory Cache is selected
				as the memory manager.
			</p>
			<source>
				<![CDATA[
# DEFAULT CACHE REGION
jcs.default=DC
jcs.default.cacheattributes=
    org.apache.jcs.engine.CompositeCacheAttributes
jcs.default.cacheattributes.MaxObjects=1000
jcs.default.cacheattributes.MemoryCacheName=
    org.apache.jcs.engine.memory.lru.LRUMemoryCache
jcs.default.cacheattributes.UseMemoryShrinker=false
jcs.default.cacheattributes.MaxMemoryIdleTimeSeconds=3600
jcs.default.cacheattributes.ShrinkerIntervalSeconds=60
jcs.default.elementattributes=org.apache.jcs.engine.ElementAttributes
jcs.default.elementattributes.IsEternal=false
jcs.default.elementattributes.MaxLifeSeconds=21600
jcs.default.elementattributes.IdleTime=1800
jcs.default.elementattributes.IsSpool=true
jcs.default.elementattributes.IsRemote=true
jcs.default.elementattributes.IsLateral=true

# PRE-DEFINED CACHE REGIONS
jcs.region.testCache1=DC
jcs.region.testCache1.cacheattributes=
    org.apache.jcs.engine.CompositeCacheAttributes
jcs.region.testCache1.cacheattributes.MaxObjects=1000
jcs.region.testCache1.cacheattributes.MemoryCacheName=
    org.apache.jcs.engine.memory.lru.LRUMemoryCache
jcs.region.testCache1.cacheattributes.UseMemoryShrinker=false
jcs.region.testCache1.cacheattributes.MaxMemoryIdleTimeSeconds=3600
jcs.region.testCache1.cacheattributes.ShrinkerIntervalSeconds=60
jcs.region.testCache1.cacheattributes.MaxSpoolPerRun=500
jcs.region.testCache1.elementattributes=org.apache.jcs.engine.ElementAttributes
jcs.region.testCache1.elementattributes.IsEternal=false

# AVAILABLE AUXILIARY CACHES
jcs.auxiliary.DC=
    org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheFactory
jcs.auxiliary.DC.attributes=
    org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheAttributes
jcs.auxiliary.DC.attributes.DiskPath=${user.dir}/jcs_swap
jcs.auxiliary.DC.attributes.MaxPurgatorySize=10000000
jcs.auxiliary.DC.attributes.MaxKeySize=1000000
jcs.auxiliary.DC.attributes.MaxRecycleBinSize=5000
jcs.auxiliary.DC.attributes.OptimizeAtRemoveCount=300000
jcs.auxiliary.DC.attributes.ShutdownSpoolTimeLimit=60
        ]]>
			</source>
			<p>
				Basic JCS configuration is described in more detail
				<a href="../BasicJCSConfiguration.html">HERE</a>
			</p>
			<p>
				Element level configuration is described in more detail
				<a href="../ElementAttributes.html">HERE</a>
			</p>
			<p>
				For more information on advanced configuration options
				and the available plugins, see the User's Guide.
			</p>
		</section>

		<section name="STEP 5: Programming to JCS">
			<p>
				JCS provides a convenient class that should meet all
				your needs. It is called, appropriately enough,
				<code>org.apache.jcs.JCS</code>
			</p>
			<p>
				To get a cache region you simply ask JCS for the region
				by name. If you wanted to use JCS for City objects, you
				would do something like this:
			</p>
			<source>
				<![CDATA[
import org.apache.jcs.JCS;
import org.apache.jcs.access.exception.CacheException;

. . .

    private static final String cacheRegionName = "city";

    private JCS cache = null;

. . .
			// in your constructor you might do this
            try
            {
                setCache( JCS.getInstance( this.getCacheRegionName() ) );
            }
            catch ( CacheException e )
            {
                log.error( "Problem initializing cache for region name ["
                  + this.getCacheRegionName() + "].", e );
            }

. . .

            // to get a city out of the cache by id you might do this:
            String key = "cityId:" + String.valueOf( id );

            City city = (City) cache.get( key );

. . .

            // to put a city object in the cache, you could do this:
            try
            {
                // if it isn't null, insert it
                if ( city != null )
                {
                    cache.put( key, city );
                }
            }
            catch ( CacheException e )
            {
                 log.error( "Problem putting "
                   + city + " in the cache, for key " + key, e );
            }
        ]]>
			</source>
		</section>

	</body>
</document>