Using Coherence and Oracle Database as the CacheStore

Question

We are working on implementing a solution using Coherence and Oracle Database as the CacheStore. We initially implemented the Cache as a distributed-scheme which in turn uses the backing-map-scheme. We are trying to introduce transaction management and I used a scheme-ref in a transactional-scheme to point to an already existing distributed-scheme. However when I bring up the server, my custom coherence-cache-config.xml file is not recognized and Coherence comes up with the default setting. Given below is the snippet of my configuration file.
1)     I would like to understand why the below configuration doesn’t work and am I doing it the right way? If not, what is the correct way of doing it?
2)     There are a multiple transaction management options given in the documentation. Which are the ones that will work with a distributed-scheme and read-write-backing-map-scheme?
3)     If transactional-schemes cannot work with distributed-scheme, what is the best way to have a distributed cache with a oracle database as a cache store?
<caching-scheme-mapping>
<cache-mapping>
<cache-name>id<cache-name>
<scheme-name>example-transactional<scheme-name>
</cache-mapping>
</caching-scheme-mapping>
<caching-schemes>
<transactional-scheme>
<scheme-name>example-transactional</scheme-name>
<scheme-ref>distributedcustomcache</scheme-ref>
<thread-count>10</thread-count>
</transactional-scheme>
<distributed-scheme>
<scheme-name>distributedcustomcache</scheme-name>
<service-name>DistributedCache</service-name>
<backing-map-scheme>
<read-write-backing-map-scheme>
<internal-cache-scheme>
<local-scheme>
<!--scheme-ref>categories-eviction</scheme-ref-->
<scheme-name>inMemory</scheme-name>
</local-scheme>
</internal-cache-scheme>
<cachestore-scheme>
<class-scheme>
<class-name>spring-bean:coherenceCacheStore</class-name>
<init-params>
<init-param>
<param-name>setEntityName</param-name>
<param-value>{cache-name}</param-value>
</init-param>
</init-params>
</class-scheme>
</cachestore-scheme>
<!--refresh-ahead-factor>0.5</refresh-ahead-factor-->
</read-write-backing-map-scheme>
</backing-map-scheme>
<autostart>true</autostart>
</distributed-scheme>

Answer 1

Hi,
If you look at the documentation for transactional-scheme here: http://docs.oracle.com/cd/E24290_01/coh.371/e22837/appendix_cacheconfig.htm#BHCIABHA
you will see that it says The transactional-scheme element defines a transactional cache, which is a specialized distributed cache. That means that a transactional-scheme is already a distributed-scheme.
You will see from the same documentation above that there is no way in a transactional-scheme to configure things like cache-stores or listeners or even the backing-map-scheme as these are not supported on a transactional-scheme - so you cannot use a cache store.
Personally I would not use transactional-scheme unless you have some really big reason to do so - the restrictions far outweigh any perceived advantage of having a transaction. There are better ways to build applications so they do not require transactions, that is what we have been doing for years with Coherence so far, and there is no real reason to change that.
JK