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| |
| <document> |
| |
| <properties> |
| <title>Turbine Services - Global Cache Service</title> |
| <author email="jvanzyl@apache.org">Jason van Zyl</author> |
| </properties> |
| |
| <body> |
| |
| <section name="Global Cache Service"> |
| |
| <p> |
| The Global Cache Service provides an object cache that you can call |
| from anywhere in your application to temporarily store objects. An example |
| of its use may be to store the names of Countries that you use throughout |
| your application to populate a look up list. If you normally store the |
| information about Countries in a database, you can increase the performance |
| of your application by using the Cache and decreasing the number of hits |
| against the database. |
| </p> |
| |
| </section> |
| |
| <section name="Configuration"> |
| |
| <source><![CDATA[ |
| # ------------------------------------------------------------------- |
| # |
| # S E R V I C E S |
| # |
| # ------------------------------------------------------------------- |
| # Classes for Turbine Services should be defined here. |
| # Format: services.[name].classname=[implementing class] |
| # |
| # To specify properties of a service use the following syntax: |
| # service.[name].[property]=[value] |
| |
| services.GlobalCacheService.classname=org.apache.turbine.services.cache.TurbineGlobalCacheService |
| . |
| . |
| . |
| |
| # ------------------------------------------------------------------- |
| # |
| # C A C H E S E R V I C E |
| # |
| # ------------------------------------------------------------------- |
| |
| # Interval at which the cache will be checked. The default is |
| # 5000ms or 5 seconds. |
| |
| services.GlobalCacheService.cache.check.frequency = 5000 |
| |
| ]]></source> |
| |
| </section> |
| |
| <section name="Usage"> |
| |
| <source><![CDATA[ |
| |
| GlobalCacheService gs = null; |
| try |
| { |
| /* |
| * Look for the item in the cache. |
| * If it doesn't exist or the item is stale, |
| * the cache will throw an exception. |
| */ |
| gs = (GlobalCacheService)TurbineServices.getInstance() |
| .getService(GlobalCacheService.SERVICE_NAME); |
| |
| CachedObject obj = gs.getObject("cached_object"); |
| |
| data.setMessage( data.getScreen() + " Got " + |
| obj.getContents().toString() + " from global cache!" ); |
| } |
| catch(ObjectExpiredException gone) |
| { |
| /* |
| * Add the item to the cache. |
| */ |
| gs.addObject("cached_object", |
| new CachedObject("in_the_cache",5000)); |
| |
| data.setMessage( data.getScreen() + |
| " Refreshed/or added new item to" + |
| " the cache! Expires in 5 seconds" ); |
| } |
| |
| ]]></source> |
| |
| <p> |
| You can also place an expiration time on your objects so the Service will |
| automatically remove them when they expire. If you don't specify an expiration |
| time, the Service uses the default time set by the property |
| <em>cache.check.frequency</em> in the TurbineResources.properties |
| file. To see an example, look at the file <strong>TestGlobalCache.java</strong> |
| located in the actions folder. |
| </p> |
| |
| </section> |
| |
| </body> |
| </document> |
