Connecting to local Coherence instance with WKA instead of Multicast

I have been trying to setup a test environment for a local Coherence cache implementation for sometime, and the information found via Google was not that helpful in understanding why the client application (in this case the UltraESB) was not connecting to the already created Coherence cluster using WKA, and was trying to create its own cluster with Multicast.

The System properties I passed to the JVM included the following, but the issue was not necessarily on these as I found out with my limited knowledge of Coherence.

The key lesson was - the System properties being correct was not enough for WKA to function properly!

wrapper.java.additional.13=-Dtangosol.coherence.cluster=adrt-cluster
wrapper.java.additional.14=-Dtangosol.coherence.management=all
wrapper.java.additional.15=-Dtangosol.coherence.cacheconfig=coherence/xxxx-cache-config.xml
wrapper.java.additional.16=-Dtangosol.coherence.localhost=127.0.0.1
wrapper.java.additional.17=-Dtangosol.coherence.localport=15000
wrapper.java.additional.18=-Dtangosol.coherence.wka.address=127.0.0.1
wrapper.java.additional.19=-Dtangosol.coherence.wka.port=15000
wrapper.java.additional.20=-Dtangosol.coherence.ttl=0
wrapper.java.additional.21=-Dtangosol.coherence.distributed.localstorage=false

The solution was to create a new file "tangosol-coherence-override.xml" and place it in the classpath (make sure its at the start to get picked up before any others - if any)

<?xml version='1.0'?>
<coherence  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
            xmlns="http://xmlns.oracle.com/coherence/coherence-operational-config"
            xsi:schemaLocation="http://xmlns.oracle.com/coherence/coherence-operational-config coherence-operational-config.xsd">    

  <cluster-config>
    <unicast-listener>
            <well-known-addresses>
                <socket-address id="1">
                        <address>127.0.0.1</address>
                        <port>15000</port>
                </socket-address>
        </well-known-addresses>
        <address>127.0.0.1</address>
        <port>15000</port>
    </unicast-listener>
  </cluster-config>

  <logging-config>
    <severity-level system-property="tangosol.coherence.log.level">9</severity-level>
    <character-limit system-property="tangosol.coherence.log.limit">0</character-limit>
  </logging-config>
</coherence>

If your client "connects" to the WKA cluster you will see the following, and you can notice that it connected to an already existing cluster with a different process

WellKnownAddressList(Size=1,
  WKA{Address=127.0.0.1, Port=15000}
  )
MasterMemberSet(
  ThisMember=Member(Id=3, Timestamp=2015-08-18 12:24:32.153, Address=127.0.0.1:15002, MachineId=60314, Location=site:,machine:localhost,process:5634)
  OldestMember=Member(Id=1, Timestamp=2015-08-18 12:24:07.652, Address=127.0.0.1:15000, MachineId=60314, Location=site:,machine:localhost,process:5366, Role=CoherenceServer)

And if it didn't connect with WKA, and created its own Multicast group you would see the following, where you can also notice that the client you just started is the only member of that new cluster

Group{Address=224.12.1.0, Port=12100, TTL=0}
MasterMemberSet(
  ThisMember=Member(Id=1, Timestamp=2015-08-18 10:25:08.389, Address=127.0.0.1:15002, MachineId=60314, Location=site:,machine:localhost,process:4278)
  OldestMember=Member(Id=1, Timestamp=2015-08-18 10:25:08.389, Address=127.0.0.1:15002, MachineId=60314, Location=site:,machine:localhost,process:4278)