WAS v8.5 > End-to-end paths > Dynamic caching > Improving service with the dynamic cache service > Tasks: Using the dynamic cache service to improve performance


Use DistributedMap and DistributedObjectCache for the dynamic cache


Overview

Java EE apps can use DistributedMap and DistributedObjectCache to cache and share Java objects.

Bind the default cache instance to the global JNDI namespace using...

The default dynamic cache instance is created if the dynamic cache service is enabled in the dmgr console.

Multiple instances of the DistributedMap and DistributedObjectCache interfaces on the same JVM enable applications to separately configure cache instances as needed. Each instance of the DistributedMap interface has its own properties. Place classes in a shared library defined at the cell, node, or server level. Place JAR files in a shared library when we deploy the application in a cluster with replication enabled. Simply turning on replication does not require a shared library; however, if you are using application-specific Java objects, such as cache key or cache value, those Java classes are required to be in the shared library.

In each server create a class loader and associate it with the shared library


Configure cache instances

Methods for configuring cache instances include...

  1. Configure default cache instances

    2. The default servlet cache instance...

      services/cache/basecache

    Created when the server starts, if servlet caching is enabled.

    The default object cache instance...

      services/cache/distributedmap

    ...is always created when the server starts.

    1. In the dmgr console, select...

        Servers | Server Types | WebSphere application servers | server_name | Container services | Dynamic cache service

    2. Configure other cache settings.

    3. Click Apply or OK.

    4. Restart WebSphere Application Server.

    We can use the following code to look up the cache instances: 

    InitialContext ic = new InitialContext();
DistributedMap dm1 = (DistributedMap)ic.lookup("services/cache/instance_one");
DistributedMap dm2 = (DistributedMap)ic.lookup("services/cache/instance_two");

// or 

InitialContext ic = new InitialContext();
DistributedObjectCache dm1 = (DistributedObjectCache)ic.lookup("services/cache/instance_one");
DistributedObjectCache dm2 = (DistributedObjectCache)ic.lookup("services/cache/instance_two");

  2. Configure servlet cache instances

    3. A servlet cache instance is a location, in addition to the default servlet cache, where dynamic cache can store, distribute, and share data. By using servlet cache instances, the applications have greater flexibility and better tuning of the cache resources. The JNDI name specified for the cache instance is mapped to the name attribute in the <cache instance> tag in the cachespec.xml configuration file.

    Servlet caches cannot be looked up. An attempt to do a look up fails, and returns null.

    1. In the dmgr console, click...

        Resources | Cache instances | Servlet cache instances

    2. Enter the scope, as follows:

      • CELL SCOPE
      • NODE SCOPE
      • SERVER SCOPE

    3. Enter the required display name for the resource in the name field.

    4. Enter the JNDI name for the resource.

      Specify this name in the attribute field in the <cache-instance> tag in cachespec.xml. This tag finds the particular cache instance in which to store cache entries.

    5. Configure other cache settings.

    6. Click Apply or OK.

    7. Optional: To set up additional custom properties for this instance, click...

        Resources | Cache instances | Servlet cache instances | servlet_cache_instance_name | Custom properties | New

    8. Optional: Enter the name of the custom property in the Name field.

      Use the custom property with scope...

        Per cache instance only

      For example...

        createCacheAtServerStartup

    9. Enter a valid value for the property in the Value field.

    10. Save the property and restart WAS.

  3. Configure object cache instances

    4. An object cache instance is a location, in addition to the default object cache, where dynamic cache can store, distribute, and share data for Java EE applications. Use cache instances to give applications better flexibility and tuning of the cache resources. Use the DistributedObjectCache programming interface to access the cache instances. For more information, see the API documentation.

    Method three is an extension to method one or method two, listed above. First use either method one or method two.

    Create and configure the object cache instance, as follows:

    1. In the dmgr console, click...

        Resources | Cache instances | Object cache intances

    2. Enter the scope:

      • CELL SCOPE
      • NODE SCOPE
      • SERVER SCOPE

    3. Enter the required display name for the resource in the name field.

    4. Enter the JNDI name for the resource.

      Use this name when looking up a reference to this cache instance. The results return a DistributedMap object.

    5. Configure other cache settings.

    6. Click Apply or OK.

    7. Optional: To set up additional custom properties for this instance, click...

        Resources | Cache instances | Object cache instances | servlet_cache_instance_name | Custom properties | New

    8. Optional: Enter the name of the custom property in the Name field.

      Use the custom property with scope...

        Per cache instance only

      For example...

        createCacheAtServerStartup

    9. Enter a valid value for the property in the Value field.

    10. Save the property and restart WAS.

    If you defined two object cache instances in the dmgr console with JNDI names of...

    • services/cache/instance_one
    • services/cache/instance_two

    We can use the following code to look up the cache instances: 

    InitialContext ic = new InitialContext();
DistributedMap dm1 = (DistributedMap)ic.lookup("services/cache/instance_one"); 
DistributedMap dm2 = (DistributedMap)ic.lookup("services/cache/instance_two");

// or 

InitialContext ic = new InitialContext();
DistributedObjectCache dm1 = (DistributedObjectCache)ic.lookup("services/cache/instance_one");
DistributedObjectCache dm2 = (DistributedObjectCache)ic.lookup("services/cache/instance_two");

  4. Configure cache instances using the cacheinstances.properties file

    5. We can create cache instances using the cacheinstances.properties file and package the file in your EAR file Use the table information in the cacheinstances.properties file article as a reference of the names, values, and explanations.

    The first line defines the cache instance name. The subsequent lines define custom properties. The formats are as follows: 

    cache.instance.x=InstanceName
cache.instance.x.customPropertyName=customPropertyValue
    where:

    • x is the instance name number, which starts with 0.

    • customPropertyName is the custom property name.

      Use the custom property with scope indicated per cache instance only.

    • customPropertyValue is the possible custom property value.

    The following is an example of how we can create additional cache instances using the cacheinstances.properties. file: 

    cache.instance.0=/services/cache/instance_one
cache.instance.0.cacheSize=1000
cache.instance.0.enableDiskOffload=true
cache.instance.0.diskOffloadLocation=${app_server_root}/diskOffload
cache.instance.0.flushToDiskOnStop=true
cache.instance.0.useListenerContext=true
cache.instance.0.enableCacheReplication=false
cache.instance.0.disableDependencyId=false
cache.instance.0.htodCleanupFrequency=60
cache.instance.1=/services/cache/instance_two
cache.instance.1.cacheSize=1500
cache.instance.1.enableDiskOffload=false
cache.instance.1.flushToDiskOnStop=false
cache.instance.1.useListenerContext=false
cache.instance.1.enableCacheReplication=true
cache.instance.1.replicationDomain=DynaCacheCluster
cache.instance.1.disableDependencyId=true

    The preceding example creates two cache instances named instance_one and instance_two. Cache instance_one has a cache entry size of 1,000 and instance_two has a cache entry size of 1,500. Disk offload is enabled in instance_one and disabled in instance_two. Use listener context is enabled in instance_one and disabled in instance_two. Flush to disk on stop is enabled in instance_one and disabled in instance_two. Cache replication is enabled in instance_two and disabled in instance_one. The name of the data replication domain for instance_two is DynaCacheCluster. Dependency ID support is disabled in instance_two.

    Place the cacheinstances.properties file in either the application server or application class path. For example, we can use the application WAR file, WEB-INF\classes directory or server_root\classes directory. The first entry in the properties file (cache.instance.0) specifies the JNDI name for the cache instance in the global namespace.

    We can use the following code to look up the cache instance: 

      InitialContext ic = new InitialContext();
     DistributedMap dm1 =
(DistributedMap)ic.lookup("services/cache/instance_one");
     DistributedMap dm2 =
(DistributedMap)ic.lookup("services/cache/instance_two");

// or 
InitialContext ic = new InitialContext();
DistributedObjectCache dm1 =  (DistributedObjectCache)ic.lookup("services/cache/instance_one");

DistributedObjectCache dm2 = (DistributedObjectCache)ic.lookup("services/cache/instance_two");

  5. Resource reference

    6. This method is an extension to method three and method four, listed above. First use either method three or method four.

    Define a resource-ref in your module deployment descriptor (web.xml and ibm-web-bnd.xmi files) and look up the cache using the java:comp namespace. The following resource-ref example uses web.xml: 

    <resource-ref>   <res-ref-name>dmap/LayoutCache</res-ref-name>   <res-type>com.ibm.websphere.cache.DistributedMap</res-type>   <res-auth>Container</res-auth>   <res-sharing-scope>Shareable</res-sharing-scope> </resource-ref> <resource-ref>   <res-ref-name>dmap/UserCache</res-ref-name>   <res-type>com.ibm.websphere.cache.DistributedMap</res-type>   <res-sharing-scope>Shareable</res-sharing-scope> </resource-ref>

    The following resource-ref example uses ibm-web-bnd.xmi: 

    <?xml version="1.0" encoding="UTF-8"?> <webappbnd:WebAppBinding xmi:version="2.0" xmlns:xmi="http://www.omg.org/XMI" 
xmlns:webappbnd="webappbnd.xmi" 
xmlns:webapplication="webapplication.xmi" xmlns:commonbnd="commonbnd.xmi" 
xmlns:common="common.xmi" 
xmi:id="WebApp_ID_Bnd" virtualHostName="default_host">   <webapp href="WEB-INF/web.xml#WebApp_ID"/>   <resRefBindings xmi:id="ResourceRefBinding_1" 
jndiName="services/cache/instance_one">   <bindingResourceRef href="WEB-INF/web.xml#ResourceRef_1"/>   </resRefBindings>   <resRefBindings xmi:id="ResourceRefBinding_2" 
jndiName="services/cache/instance_two">   <bindingResourceRef href="WEB-INF/web.xml#ResourceRef_2"/>   </resRefBindings>   </webappbnd:WebAppBinding>

    For IBM extension and binding files, the .xmi or .xml file name extension is different depending on whether you are using a pre-Java EE 5 application or module or a Java EE 5 or later application or module. An IBM extension or binding file is named ibm-*-ext.xmi or ibm-*-bnd.xmi where * is the type of extension or binding file such as app, application, ejb-jar, or web. The following conditions apply:

    • For apps and modules that use a Java EE version prior to version 5, the file extension must be .xmi.

    • For apps and modules that use Java EE 5 or later, the file extension must be .xml. If .xmi files are included with the application or module, the product ignores the .xmi files.

    However, a Java EE 5 or later module can exist within an application that includes pre-Java EE 5 files and uses the .xmi file name extension.

    The ibm-webservices-ext.xmi, ibm-webservices-bnd.xmi, ibm-webservicesclient-bnd.xmi, ibm-webservicesclient-ext.xmi, and ibm-portlet-ext.xmi files continue to use the .xmi file extensions. .

    The following example shows how to look up the resource-ref: 

    InitialContext ic = new InitialContext();
  DistributedMap dm1a =(DistributedMap)ic.lookup("java:comp/env/dmap/LayoutCache");
  DistributedMap dm2a =(DistributedMap)ic.lookup("java:comp/env/dmap/UserCache");
// or   DistributedObjectCache dm1a =(DistributedObjectCache)ic.lookup("java:comp/env/dmap/LayoutCache");
  DistributedObjectCache dm2a =(DistributedObjectCache)ic.lookup("java:comp/env/dmap/UserCache");

    The previous resource-ref example maps java:comp/env/dmap/LayoutCache to /services/cache/instance_one and java:comp/env/dmap/UserCache to /services/cache/instance_two. In the examples, DistributedMap dm1 and dm1a are the same object. DistributedMap dm2 and dm2a are the same object.

  6. Java virtual machine cache settings

    7. We can set the custom properties globally to affect all cache instances. This overwrites the settings in method 1, method 2 and method 3, but not method 4 (cacheinstances.properties). Configure the cache instance globally, as follows:

    1. In the dmgr console, click...

    2. Enter the name of the custom property in the Name field.

      After you find the custom property name, add the prefix...

        com.ibm.ws.cache.CacheConfig

      ...to the front of custom property name. For example, if the custom property name is createCacheAtServerStartup, enter...

        com.ibm.ws.cache.CacheConfig.createCacheAtServerStartup

    3. Enter a valid value for the property in the Value field.

    4. Save the property and restart WAS.


Subtopics

  1. Object cache instance settings
  2. Object cache instance page
  3. cacheinstances.properties file
  4. Invalidation listeners
  5. Use object cache instances
  6. Cache instances
  7. Object cache instance settings
  8. Object cache instance page
  9. Invalidation listeners


Related concepts:

Cache instances


Related


Use the dynamic cache service
Configure dynamic cache disk offload
Use object cache instances


Reference:

Java virtual machine cache settings


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