The last step is to register the Factory to the SerializationConfig. Below are the programmatic and declarative configurations for this step.

Config config = new Config();
config.getSerializationConfig().addPortableFactory( 1, new MyPortableFactory() );
<hazelcast>
  <serialization>
    <portable-version>0</portable-version>
    <portable-factories>
      <portable-factory factory-id="1">
          com.hazelcast.nio.serialization.MyPortableFactory
      </portable-factory>
    </portable-factories>
  </serialization>
</hazelcast>

Note that the id that is passed to the SerializationConfig is the same as the factoryId that the Foo class returns.