With version 2.1, Hazelcast will support MongoDB persistence integrated with Spring Data-MongoDB module. Spring MongoDB module maps your objects to equivalent MongoDB objects. To persist your objects into MongoDB you should define MongoDB mapstore in your Spring configuration as follows:

<mongo:mongo id="mongo" host="localhost" port="27017"/>

<bean id="mongoTemplate"
      class="org.springframework.data.mongodb.core.MongoTemplate">
    <constructor-arg ref="mongo"/>
    <constructor-arg name="databaseName" value="test"/>
</bean>

<bean class="com.hazelcast.spring.mongodb.MongoMapStore" id="mongomapstore">
    <property name="mongoTemplate" ref="mongoTemplate" />
</bean>

Then you can set this as mapstore for maps that you want to persist into MongoDB.

<hz:map name="user">
    <hz:map-store enabled="true" implementation="mongomapstore"
                  write-delay-seconds="0">
    </hz:map-store>
</hz:map>

By default, the key is set as id of the MongoDB object. You can override MongoMapStore class for you custom needs. For more info see Spring Data MongoDB Reference .