Issue with Custom DurableStore in Akka Cluster: Deserialization Error for DurableDataEnvelope

Akka Libraries Akka Cluster
1

Issue with Custom DurableStore in Akka Cluster: Deserialization Error for DurableDataEnvelope

I’m working on a custom DurableStore implementation in Akka Cluster using Java. My goal is to persist Akka’s Distributed Data (ddata) using a custom logic that serializes the data and stores it in a file.

Here’s the relevant configuration I’ve set up:

Akka Configuration:

akka.cluster {
    sharding {
        remember-entities = on
        remember-entities-store = ddata

        distributed-data {
            durable.keys = ["*"]
            durable.store-actor-class=com.zoho.actor.cluster.durable.CustomDurableStore
        }
    }
}

akka.actor {
    serializers {
        proto = "akka.cluster.ddata.protobuf.ReplicatorMessageSerializer"
    }

    serialization-bindings {
        "akka.cluster.ddata.DurableStore$DurableDataEnvelope" = proto
    }
}

Serialization Logic:
I am able to serialize DurableDataEnvelope successfully:

public static byte[] serializeToString(DurableDataEnvelope envelope) throws Exception {
    serializer = serialization.findSerializerFor(envelope);
    // Serialize to byte array
    byte[] serializedBytes = serializer.toBinary(envelope);
    return serializedBytes;
}

Deserialization Logic:
However, when I try to deserialize the data, I encounter the following error:

java.io.NotSerializableException: Unimplemented deserialization of message with manifest [akka.cluster.ddata.DurableStore$DurableDataEnvelope] in [akka.cluster.ddata.protobuf.ReplicatorMessageSerializer]

Here is the code for deserialization:

public static DurableDataEnvelope deserializeFromString(byte[] serializedBytes) throws Exception {
    DurableDataEnvelope ddata = (DurableDataEnvelope) serialization.deserialize(serializedBytes, DurableDataEnvelope.class).get();
    return ddata;
}

I have configured the serializer binding for DurableDataEnvelope as shown above. Despite that, it seems that deserialization is not correctly implemented or there’s something I’m missing.

Question:
What could be causing this deserialization issue, and how can I resolve it? Is there a specific step I’m missing when configuring or handling the deserialization for DurableDataEnvelope?

TIA!

2

The problem is that the serializer works with string based manifests and not class names.

You can extract the manifest using akka.serialization.Serializers#manifestFor on the serialization side, the serializer id by looking up the serializer for the object akka.serialization.Serialization#findSerializerFor and call identifier on that, store all three values in your file and then use them to call akka.serialization.Serialization#deserialize(byte[], int, String) when deserializing

1 Like
3

is there any documentation how to do this? any help wiki? @johanandren

4

I’m afraid not, reading sources of the existing LmdbDurableStore implementation is what is available.

1 Like
5

That was in Scala but im working in java which is bit confusing. And thank for the help. @johanandren will look into that.

Update: able to serialize and deserialize now.

6

Ensure your custom serializer for DurableDataEnvelope is correctly implemented and configured in Akka, and that CustomDurableStore properly handles deserialization for the envelope.

7

@markboucher