xdocs/LocalCacheConfig.xml (149 lines of code) (raw):

<?xml version="1.0"?> <!-- Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <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.jcs3.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.jcs3.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.jcs3.auxiliary.disk.DiskCacheFactory jcs.auxiliary.DC.attributes= org.apache.commons.jcs3.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.jcs3.auxiliary.remote.RemoteCacheFactory jcs.auxiliary.RFailover.attributes= org.apache.commons.jcs3.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>