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WAN Quickstart

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This section provides information about how you can start using WAN Replication with a minimal setup for both Active-Passive and Active-Active modes.

Setting Up an Active-Passive Mode

This mode usually requires configuration only on one of the clusters. Let’s say you have two clusters, one in London and the other in Tokyo. You want to replicate the updates between each other and use the one in Tokyo as the active cluster.

1 - Add the following configuration example on your cluster in Tokyo:

  • XML

  • YAML

  • Java Member API

<hazelcast>
    <wan-replication name="london-wan-rep">
        <batch-publisher>
            <publisher-id>londonPublisherId</publisher-id>
            <cluster-name>london</cluster-name>
            <target-endpoints>10.3.5.1:5701</target-endpoints>
        </batch-publisher>
    </wan-replication>

    <map name="replicatedMap">
        <wan-replication-ref name="london-wan-rep"/>
    </map>

</hazelcast>
hazelcast:
  wan-replication:
    london-wan-rep:
      batch-publisher:
        londonPublisherId:
          cluster-name: london
          target-endpoints: 10.3.5.1:5701

  map:
    replicatedMap:
      wan-replication-ref: london-wan-rep
        Config config = new Config();
        WanBatchPublisherConfig batchPublisherConfig = new WanBatchPublisherConfig()
                .setPublisherId("londonPublisherId")
                .setClusterName("london")
                .setTargetEndpoints("10.3.5.1:5701");

        WanReplicationConfig wrConfig = new WanReplicationConfig()
                .setName("london-wan-rep")
                .addBatchReplicationPublisherConfig(batchPublisherConfig);

        config.addWanReplicationConfig(wrConfig);

        config.getMapConfig("replicatedMap").setWanReplicationRef(new WanReplicationRef().setName("london-wan-rep"));

2 - Start your clusters to start using Active-Passive WAN Replication.

Basically, what we did here is defining a WAN Replication configuration (wan-replication) and configuring our map to use it (wan-replication-ref). As mentioned, this is the minimal configuration example, which is fine for most use cases. There are more configuration options for tuning the WAN Replication; see the Tuning WAN Replication section.

In the above example, we have configured the map named replicatedMap to replicate to the target cluster named london on a single endpoint, as specified with the target-endpoints element. Notice that the name of wan-replication configuration (london-wan-rep) is referenced in the map configuration using the wan-replication-ref element; this is how you make your map to use the WAN Replication feature. For now, only Hazelcast maps and caches support this feature.

The london cluster might have more members than the one specified in this example, but only that endpoint will receive the WAN events. In that case and if you want the events to be forwarded to the other cluster members, see the republishing-enabled element description in the Configuring for IMap and ICache section.

This example configuration defines a static endpoint to specify the target cluster member, using the target-endpoints element or setTargetEndpoints() method, respectively. You can also use Hazelcast’s Discovery SPI for WAN Replication to specify endpoints on various cloud infrastructures. See the Using Discovery SPI section.

Setting Up an Active-Active Mode

Using the above scenario, this mode requires configuration on both clusters.

1 - Add the following configuration example on your cluster in Tokyo:

  • XML

  • YAML

  • Java Member API

<hazelcast>
    <cluster-name>tokyo</cluster-name>
    <wan-replication name="london-wan-rep">
        <batch-publisher>
            <publisher-id>londonPublisherId</publisher-id>
            <cluster-name>london</cluster-name>
            <target-endpoints>10.3.5.1:5701</target-endpoints>
        </batch-publisher>
    </wan-replication>

    <map name="replicatedMap">
        <wan-replication-ref name="london-wan-rep"/>
    </map>

</hazelcast>
hazelcast:
  cluster-name: tokyo
  wan-replication:
    london-wan-rep:
      batch-publisher:
        londonPublisherId:
          cluster-name: london
          target-endpoints: 10.3.5.1:5701

  map:
    replicatedMap:
      wan-replication-ref: london-wan-rep
        Config config = new Config();
        config.setClusterName("tokyo");
        WanBatchPublisherConfig batchPublisherConfig = new WanBatchPublisherConfig()
                .setPublisherId("londonPublisherId")
                .setClusterName("london")
                .setTargetEndpoints("10.3.5.1:5701");

        WanReplicationConfig wrConfig = new WanReplicationConfig()
                .setName("london-wan-rep")
                .addBatchReplicationPublisherConfig(batchPublisherConfig);

        config.addWanReplicationConfig(wrConfig);

        config.getMapConfig("replicatedMap").setWanReplicationRef(new WanReplicationRef().setName("london-wan-rep"));

2 - Add the following configuration example on your cluster in London:

  • XML

  • YAML

  • Java Member API

<hazelcast>
    <cluster-name>london</cluster-name>
    <wan-replication name="tokyo-wan-rep">
        <batch-publisher>
            <publisher-id>tokyoPublisherId</publisher-id>
            <cluster-name>tokyo</cluster-name>
            <target-endpoints>32.1.1.1:5701</target-endpoints>
        </batch-publisher>
    </wan-replication>

    <map name="replicatedMap">
        <wan-replication-ref name="tokyo-wan-rep"/>
    </map>

</hazelcast>
hazelcast:
  cluster-name: london
  wan-replication:
    tokyo-wan-rep:
      batch-publisher:
        tokyoPublisherId:
          cluster-name: tokyo
          target-endpoints: 32.1.1.1:5701
  map:
    replicatedMap:
      wan-replication-ref: tokyo-wan-rep
        Config config = new Config();
        config.setClusterName("london");
        WanBatchPublisherConfig batchPublisherConfig = new WanBatchPublisherConfig()
                .setPublisherId("tokyoPublisherId")
                .setClusterName("tokyo")
                .setTargetEndpoints("32.1.1.1:5701");

        WanReplicationConfig wrConfig = new WanReplicationConfig()
                .setName("tokyo-wan-rep")
                .addBatchReplicationPublisherConfig(batchPublisherConfig);

        config.addWanReplicationConfig(wrConfig);

        config.getMapConfig("replicatedMap").setWanReplicationRef(new WanReplicationRef().setName("tokyo-wan-rep"));

3 - Start your clusters to start using Active-Active WAN Replication.

Notice the cluster-name configuration element (not the one under the batch-publisher element, but the one under the hazelcast element); this defines the name of the local Hazelcast cluster. The cluster-name defined under the batch-publisher element will need to match the name of the remote target cluster, as shown above.

When WAN replication is enabled between clusters where all members share the same cluster-name, WAN event republishing (forwarding) will not be functional. This is because WAN events can only be actioned once for each cluster, and this is tracked by recording the name of each cluster the event passes through. This mechanism prevents an infinite loop of republishing scenario.

As in the Active-Passive example shown in the previous section, this example configuration also uses a static endpoint to specify the target cluster member. See the Using Discovery SPI section for information on using the Discovery SPI to specify target members.

As mentioned previously, the above configurations are the minimal ones to get you started. In case you need to configure some additional aspects of your maps or caches that use WAN Replication, see the Configuring for IMap and ICache section.

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