Cluster Extension

    Summary

    Group service providers in a cluster, and treat them as one single provider.

    Extension Interface

    org.apache.dubbo.rpc.cluster.Cluster

    Extension Configuration

    <dubbo:protocol cluster="xxx" />
    <!-- default configuration, will take affect if cluster attribute is not configured in <dubbo:protocol>  -->
    <dubbo:provider cluster="xxx" />
    

    Existing Extensions

    • org.apache.dubbo.rpc.cluster.support.FailoverCluster
    • org.apache.dubbo.rpc.cluster.support.FailfastCluster
    • org.apache.dubbo.rpc.cluster.support.FailsafeCluster
    • org.apache.dubbo.rpc.cluster.support.FailbackCluster
    • org.apache.dubbo.rpc.cluster.support.ForkingCluster
    • org.apache.dubbo.rpc.cluster.support.AvailableCluster

    Extension Guide

    Directory layout:

    src
     |-main
        |-java
            |-com
                |-xxx
                    |-XxxCluster.java (Cluster implementation)
        |-resources
            |-META-INF
                |-dubbo
                    |-org.apache.dubbo.rpc.cluster.Cluster (plain text file with the content: xxx=com.xxx.XxxCluster)
    

    XxxCluster.java:

    package com.xxx;
     
    import org.apache.dubbo.rpc.cluster.Cluster;
    import org.apache.dubbo.rpc.cluster.support.AbstractClusterInvoker;
    import org.apache.dubbo.rpc.cluster.Directory;
    import org.apache.dubbo.rpc.cluster.LoadBalance;
    import org.apache.dubbo.rpc.Invoker;
    import org.apache.dubbo.rpc.Invocation;
    import org.apache.dubbo.rpc.Result;
    import org.apache.dubbo.rpc.RpcException;
     
    public class XxxCluster implements Cluster {
        public <T> Invoker<T> merge(Directory<T> directory) throws RpcException {
            return new AbstractClusterInvoker<T>(directory) {
                public Result doInvoke(Invocation invocation, List<Invoker<T>> invokers, LoadBalance loadbalance) throws RpcException {
                    // ...
                }
            };
        }
    }
    

    META-INF/dubbo/org.apache.dubbo.rpc.cluster.Cluster:

    xxx=com.xxx.XxxCluster