About this task
There are two types of cache instances you can create with
this procedure, object cache instances and servlet cache instances.
An object cache instance is a location in addition to the default
shared dynamic cache where Java 2 Platform, Enterprise Edition (J2EE)
applications can store, distribute, and share objects. After configuring
object cache instances, you can use the
DistributedMap or
DistributedObjectCache interfaces in the
com.ibm.websphere.cache package to programmatically access
your cache instances. See the
Additional Application Programming Interfaces (APIs) for more information about the
DistributedMap or
DistributedObjectCache interfaces. Servlet
cache instances are locations in addition to the default dynamic cache
where dynamic cache can store, distribute, and share the output and
the side effects of an invoked servlet. By configuring a servlet cache
instance, your applications have greater flexibility and better tuning
of cache resources. The Java Naming and Directory Interface (JNDI)
name that is specified for the cache instance in the administrative
console maps to the cache instance element in the
cachespec.xml configuration file. Any <cache-entry> elements that are specified
within a <cache-instance> element are created in that specific
cache instance. Any <cache-entry> elements that are specified outside
of a <cache-instance> element are stored in the default dynamic
cache instance. See
Cache instances for more information about
object and servlet type cache instances.
The steps in this procedure
are for Version 8.0 of the
WebSphere Application Server administrative console. This information may vary slightly
depending on the version of
WebSphere Application Server you are using.
Note: - WebSphere eXtreme Scale Version 8.6
is not supported on versions of WebSphere Application Server prior to Version 7.0.
What to do next
By default, each dynamic cache instance
that is configured on WebSphere Application Server corresponds to a dynamic cache data grid that has the
same name as the JNDI name of the cache instance. Also, by default,
the data for that cache instance is stored in a dynamic map within
that dynamic cache data grid, and the suffix for that dynamic map
name also corresponds to the JNDI name of the cache instance. For
example, if you were to configure a cache instance on WebSphere Application Server with a JNDI
name of cache1, then a dynamic cache data grid is created with the name cache1. Inside
data grid cache1, a dynamic map named IBM_DC_PARTIONED_cache1 is created
to store the data.
In most cases, this configuration does not
need to be changed. However, in some circumstances, you might want
multiple cache instances, with different JNDI names, to map to different
dynamic maps within the same data grid instance. In other circumstances,
you might want multiple cache instances, with the same JNDI name,
to map to different dynamic cache data grid instances or different
dynamic map instances within the same dynamic cache data grid.
For example, if you have an application that uses the default dynamic
cache instance (baseCache), you might want to use the same data grid for both of your test level and production level environments, while
you keep the cached data in separate data grids or separate dynamic
maps within the same data grid.
You can set the following
custom properties on the cache instances to control this configuration:
Tip: These properties can be especially useful when you use
the default dynamic cache instance (baseCache), since the JNDI name
for the cache is automatically set to baseCache and cannot be changed.
- com.ibm.websphere.xs.dynacache.grid_name
- Use this custom property to specify the name of the dynamic cache
data grid instance to which a dynamic cache instance corresponds.
- com.ibm.websphere.xs.dynacache.cache_name
- Use this custom property to specify the name to be used, in place
of the JNDI name, for both the dynamic cache data grid name and the
dynamic map inside that data grid. If the com.ibm.websphere.xs.dynacache.grid_name custom property is also set, then the value of this property applies
only to the dynamic map name.
For information about how to set these properties,
see
Customizing a dynamic cache instance with custom properties.