Split PayloadCodec into two Encoder/Decoder interfaces and have a separate config for each

[ddavidyuk]

Is your feature request related to a problem? Please describe. There are multiple microservices, each one using a different encoding scheme for outgoing Temporal payloads, e.g.: Microservice A: binary/gzip Microservice B: binary/encrypt

Each microservice hosts its own activities and workflows that invoke each other.

Describe the solution you'd like We should be able to configure Java SDK on Microservice A to encode payloads using binary/gzip but decode the incoming payloads using either binary/gzip or binary/encrypt. Same for Microservice B (but use binary/encrypt for encoding).

Here are some code examples:

public interface PayloadEncoder {
    ByteString getEncoding();

    Payload encode(Payload payload) throws DataConverterException;
}

public interface PayloadDecoder {
    ByteString getEncoding();

    Payload decode(Payload payload) throws DataConverterException;

    default boolean willDecode(Payload payload) {
        ByteString encoding = payload.getMetadataOrDefault(EncodingKeys.METADATA_ENCODING_KEY, null);
        return getEncoding().equals(encoding);
    }
}

public class PayloadCodecs {
    final List<PayloadEncoder> encoders;
    final List<PayloadDecoder> decoders;

    public Payload encode(Payload payload) throws DataConverterException {
        Payload result = payload;
        for (PayloadEncoder encoder : encoders) {
            result = encoder.encode(result);
        }

        return result;
    }

    public Payload decode(Payload payload) throws DataConverterException {
        return decoders.stream().filter(decoder -> decoder.willDecode(payload))
                .findFirst()
                .map(decoder -> decode(decoder.decode(payload))) // !!! recursive call
                .orElse(payload);
    }
}

This can also be integrated into a Spring Boot module like this:

@Bean
// get all PayloadEncoder/Decoder beans, use all decoder beans for decoding (will be selected based on 
// the Payload's encoding header)
// use only select encoder beans for encoding
// example: temporal.payload-encoding=binary/encrypt,binary/gzip - first gzip the payload and then encrypt
public PayloadCodecs payloadCodecs(List<PayloadDecoder> decoders, 
List<PayloadEncoders> encoders, 
@Value("${temporal.payload-encoding}") List<String> encodings ) {
       return new PayloadCodecs(selectEncoders(encoders, encodings), decoders);
}

Describe alternatives you've considered Use our own library on top of Temporal Java SDK

Additional context Add any other context or screenshots about the feature request here.