How to access a Coherence cache with the same name across multiple clusters?

StackOverflow https://stackoverflow.com/questions/9802654

  •  25-05-2021
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Question

I have several Oracle Coherence clusters, and on each cluster I have the same set of caches with the same cache names. How can I access a single cache (say "Cache1") from each cluster within my application? For example, I may want to check the count of "Cache1" across all environments to display to the user.

The clusters are set up using Coherence Extend, and I have setup the client-side cache-config with separate cache-mappings and remote-cache-schemes for each cluster. However, if I set the cache-name element to "Cache1" for each cluster, it only retrieves data from the first cluster listed in the xml. If I set it to something else (e.g. "Cache1-Dev1"), I get a Tangosol.IO.Pof.PortableException with the message 'No scheme for cache: "Cache1-Dev1"'.

<cache-config xmlns="http://schemas.tangosol.com/cache">
  <caching-scheme-mapping>
    <cache-mapping>
      <cache-name>Cache1-Dev1</cache-name>
      <scheme-name>extend-direct-dev1</scheme-name>
    </cache-mapping>
    <cache-mapping>
      <cache-name>Cache1-Dev2</cache-name>
      <scheme-name>extend-direct-dev2</scheme-name>
    </cache-mapping>
  </cache-scheme-mapping>
<caching-schemes>
<remote-cache-scheme>
  <scheme-name>extend-direct-dev1</scheme-name>
  <service-name>ExtendTcpCacheService-dev1</service-name>
  <initiator-config>
    <tcp-initiator>
      <remote-addresses>
        <socket-address>
          <address>dev1-address</address>
          <port>9500</port>
        </socket-address>
      </remote-addresses>
    </tcp-initiator>
    <outgoing-message-handler>
      <request-timeout>60s</request-timeout>
    </outgoing-message-handler>
  </initiator-config>
</remote-cache-scheme>
<remote-cache-scheme>
  <scheme-name>extend-direct-dev2</scheme-name>
  <service-name>ExtendTcpCacheService-dev2</service-name>
  <initiator-config>
    <tcp-initiator>
      <remote-addresses>
        <socket-address>
          <address>dev2-address</address>
          <port>9500</port>
        </socket-address>
      </remote-addresses>
    </tcp-initiator>
    <outgoing-message-handler>
      <request-timeout>60s</request-timeout>
    </outgoing-message-handler>
  </initiator-config>
</remote-cache-scheme>
</cache-config>
Was it helpful?

Solution

Found the answer elsewhere.

First, get the proxy service instance, and cast it to a CacheService. You should then be able to get the cache from that service instance.

Java implementation:

Service service = CacheFactory.getService("ExtendTcpCacheService-dev1");
CacheService cacheService = (CacheService) service;
NamedCache cache = cacheService.ensureCache("Cache1");

The code is almost identical in C#:

var service = CacheFactory.GetService("ExtendTcpCacheService-dev1");
var cacheService = (ICacheService)service;
var cache = cacheService.EnsureCache("Cache1");

This also means you no longer need to list the caches in the cache-mapping section of your cache-config xml file, though you need at least one cache-mapping containing cache-name and scheme-name for coherence to run, even if it isn't used.

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