Using NCache as NHibernate Second Level Cache
NHibernate has a first level or session level cache which is used by default. Each session contains its own session level cache which is not shared with other sessions. This cache is disposed whenever the session is closed. However, NHibernate allows to use second level, across session cache which spans across sessions’ life time and can be shared by multiple sessions.
NCache provides a second level or process level cache for NHibernate by
implementing NHibernate's ICacheProvider
and ICache
interfaces. This enables
NCache to be used as NHibernate second cache in existing NHibernate application
without any code change. All that’s needed is to change NHibernate configuration
file to plug-in NCache as cache provider and distributed caching can be used.
Second level cache can be configured by enabling the use of second level cache and configuring second level cache provider in NHibernate configurations.
Configuring NHibernate Application to use NCache as Second Level Cache
Important
Use NHibernate Version 2.2.3 in order to use NCache as NHibernate Second Level Cache.
Create NHibernate region in Web.config
Add the <hibernate-configuration>
in Web.config under the <configSections>
tag:
<configSections>
<section name="hibernate-configuration" type="NHibernate.Cfg.ConfigurationSectionHandler, NHibernate" />
<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net" />
</configSections>
Specify Configurations for NHibernate Region
- Place NCache’s NHibernate Provider assembly
Alachisoft.NCache.Integrations.NHibernate.Cache.dll
located at%NCHOME%/integration/nhibernate/assembly/
in the application's base directory.
Or
Intall NCache NuGet pacakge for application without NCache installation. Execute any of the following commands in Package Manager Console inside Visual Studio:
- For Enterprose Edition:
Install-Package NHibernate.NCache
- For Professional Edition:
Install-Package NHibernate.NCache.Professional
- For OpenSource:
Install-Package NHibernate.NCache.OpenSource
Configure NCache as NHibernate's second level cache provider by adding the
cache.provider_class
property under the specified region (<hibernate-configuration>
).Enable the use of second level cache in application by setting the
cache.use_second_level_cache
property totrue
.
<hibernate-configuration xmlns="urn:nhibernate-configuration-2.2">
<session-factory>
<property name="cache.provider_class">Alachisoft.NCache.Integrations.NHibernate.Cache.NCacheProvider, Alachisoft.NCache.Integrations.NHibernate.Cache</property>
<property name="cache.use_second_level_cache">true</property>
</session-factory>
</hibernate-configuration>
Specify Application ID for NCache NHibernate Provider
NCache Provider for NHibernate identifies each application by an application ID. This ID is used to find the appropriate configuration for that application from NCache configuration file for NHibernate (NCacheNHibernate.xml). This application id must be specified in application's configuration file (Web.config):
<appSettings>
<add key="ncache.application_id" value="myapp" />
</appSettings>
Configuring Cacheable Objects
Enabling the use of second level cache does not cache each class object by
default. Instead classes needed to be cached are to be marked cacheable in class
mapping (.hbm.xml
) file. To mark a class cacheable, add the following tag in
class's configuration:
<cache usage="read-write" region ="AbsoluteExpirationRegion"/>
In the above tag, properties usage
and region
can be changed.
Members | Description |
---|---|
region |
Specifies the name of second level cache region to be used for this class objects. If no region is specified, Fully Qualified Name (FQN) will be used as region name with default region configurations. |
usage |
Specifies caching concurrency strategy to be used for this class. NHibernate allows following three concurrency strategies to be used for caching:Read-Write Nonstrict-Read-Write Read-Only |
Configuring Cache Regions
NHibernate uses cache regions to store objects. NCache allows NHibernate cache regions to
be configured with different properties. For this purpose, NCache has a
configuration file named NCacheNHibernate.xml, which contains all regions’
configurations used by NHibernate Second Level Cache. This file can be
placed at root directory of application or in %NCHOME%/config
(Windows) or opt\ncache\config
(Linux).
<configuration>
<application-config application-id="myapp" enable-cache-exception="true" default-region-name="default" key-case-sensitivity="false">
<cache-regions>
<region name="AbsoluteExpirationRegion" cache-name="mycache"
priority="Default" expiration-type="sliding" expiration-period="180" />
<region name="default" cache-name="mycache" priority="default"
expiration-type="none" expiration-period="0" />
</cache-regions>
</application-config>
</configuration>
Multiple application configurations can be specified in NCacheNHibernate.xml.
Any NHibernate application will use one of the specified configurations based on
the application-id
specified in applications App.config/Web.config file.
Following are the configurable options in application-config
section.
Member | Description |
---|---|
application-id |
This option lets the user specify a unique id for current application-config . This id is used to select appropriate configuration for a particular application. |
enable-cache-exception |
Identifies whether the exceptions if occurred in NCache will be propagated to NHibernate provider. |
default-region-name |
Allows to specify a default region for the application. If a particular region's configurations are not found, default region configurations will be used. Specified default region configuration must exist in cache-regions section. |
key-case-sensitivity |
This option allows to specify whether cache keys will be case sensitive or not. This option has to be configured according to database used. If database is case-sensitive set this option true, otherwise false. |
cache-regions |
This section lets the user configure multiple cache regions for NHibernate application. Each region's configuration is specified in region tag. |
region |
This tag contains the configurations for one particular region. Following options can be configured for any particular region.
Default Low BelowNormal Normal AboveNormal NotRemovable expiration-type: This options allows to specify type of expiration for any item in this region. Possible values are absolute /sliding /none .expiraion-period: Allows to specify expiration period if absolute/sliding expiration is configured. Its value should be greater than 0. |
database-dependencies |
It lets the user specify database dependencies for current NHibernate application.
|
See Also
Using NHibernate Query Caching
Configuring Database Synchronization with NHibernate
Entity Framework Cache Provider
AppFabric to NCache Migration