Event Filtering API

Starting with Hazelcast 3.6, WAN replication allows you to intercept WAN replication events before they are placed to WAN event replication queues by providing a filtering API. Using this API, you can monitor WAN replication events of each data structure separately.

You can attach filters to your data structures using the filter property of wan-replication-ref configuration inside hazelcast.xml as shown below. You can also configure it using the programmatic configuration.

<hazelcast>
    ...
    <map name="testMap">
        <wan-replication-ref name="test">
            <filters>
                <filter-impl>com.example.MyFilter</filter-impl>
                <filter-impl>com.example.MyFilter2</filter-impl>
            </filters>
        </wan-replication-ref>
    </map>
    ...
</hazelcast>

As shown in the above configuration, you can define more than one filter. Filters are called in the order that they are introduced. A WAN replication event is only eligible to publish if it passes all the filters.

Map and Cache have different filter interfaces: MapWanEventFilter and CacheWanEventFilter. Both of these interfaces have the method filter which takes the following parameters:

mapName/cacheName: Name of the related data structure.
entryView: EntryView or CacheEntryView depending on the data structure.
eventType: Enum type - UPDATED(1), REMOVED(2) or LOADED(3) - depending on the event.

LOADED events are filtered out and not replicated to target cluster.