{"id":107,"date":"2009-10-14T16:33:15","date_gmt":"2009-10-14T16:33:15","guid":{"rendered":"http:\/\/shirishranjit.com\/blog1\/?p=107"},"modified":"2015-07-25T09:18:04","modified_gmt":"2015-07-25T13:18:04","slug":"google-app-engine-memcache-how-can-you-create-a-multiple-memcache","status":"publish","type":"page","link":"https:\/\/shirishranjit.com\/blog1\/entertainment\/google-app-engine-memcache-how-can-you-create-a-multiple-memcache","title":{"rendered":"Google App Engine: Memcache – How can you create a multiple Memcache?"},"content":{"rendered":"

(http:\/\/code.google.com\/appengine\/docs\/java\/memcache\/overview.html)<\/span><\/p>\n

Google App Engine provides Memcache as a part of App Engine. Memcache implements the JCache interface (javax.cache). <\/span><\/p>\n

The App Engine provides <\/span>MemcacheService<\/span> and implementation of jCache API. There are a lot of useful features that the jCache does not provide. <\/span><\/p>\n

Here is how one can create a multiple Memcache in App Engine.<\/span><\/p>\n

MemcacheService <\/span>cacheA<\/span> = MemcacheServiceFactory.getMemcacheService();<\/span><\/p>\n

cacheLock<\/span>.setNamespace( <\/span>“A”<\/span> );<\/span><\/p>\n

MemcacheService <\/span>cacheB<\/span> = MemcacheServiceFactory.getMemcacheService();<\/span><\/p>\n

cacheTxnLocked<\/span>.setNamespace( <\/span>“B”<\/span> );<\/span><\/p>\n

MemcacheService <\/span>cacheC<\/span> = MemcacheServiceFactory.getMemcacheService();<\/span><\/p>\n

cacheAllTxns<\/span>.setNamespace( <\/span>“C”<\/span> );<\/span><\/p>\n

Once you create the Memcache using the <\/span>MemcacheServiceFactory<\/span>, you need to set the Namespace. The \u201cNamespace\u201d causes the cache to be different. <\/span><\/p>\n

So, if you do not set the \u201cNamespace\u201d on the cache, then all the cache that you get from the <\/span>MemcacheService<\/span> will be the same.<\/span><\/p>\n

A pattern to use Memcache in the App Engine (or in any application server) is to use a Singleton to hold the cache. Singleton allows to initialize the different caches and works as a Facade to the Memcache. <\/span><\/p>\n

This design has many useful features. Few of those are:<\/span><\/p>\n