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The Data Serviceshub (DSH) Platform SDK facilitates easier development of applications on the DSH. It abstracts over the authentication and configuration of your Kafka clients against the policies of the DSH.

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package dsh.messages;

import com.google.protobuf.Message;
import com.google.protobuf.Parser;

import java.util.function.Function;

/**
 * General purpose serializing and deserializing functions to operate on the protobuf Envelopes.
 *
 * The definition as {@code Function} of the Serdes makes it possible to directly use the in the Java Streams API:
 * {@code
 *
 * List listOfDataEnvelopes = ...
 * listOfDataEnvelopes.stream()
 *      .map(Serdes.serializeKey)
 *      .forEach( ... )
 * }
 */
public class Serdes {

    /**
     * Exception to indicate something went wrong while serializing/deserializing the raw data
     * into Key- and/or DataEnvelopes.
     */
    public static class SerializationException extends RuntimeException {
        private static final long serialVersionUID = 4023244989841487397L;
        public SerializationException(Throwable cause) { super(cause); }
    }

    private static  T fromBytes(Parser parser, byte[] bytes) {
        if(bytes == null) return null;
        try {
            return parser.parseFrom(bytes);
        } catch (Exception e) {
            throw new SerializationException(e);
        }
    }

    private static  byte[] toBytes(T msg) {
        if(msg == null) return null;
        try {
            return msg.toByteArray();
        } catch (Exception e) {
            throw new SerializationException(e);
        }
    }

    /**
     * Function to deserialize a KeyEnvelope
     * @see dsh.messages.Envelope.KeyEnvelope
     * @see Serdes#fromBytes(Parser, byte[])
     */
    public static Function deserializeKey = (byte[] bytes) -> Serdes.fromBytes(Envelope.KeyEnvelope.parser(), bytes);

    /**
     * Function to deserialize a DataEnvelope
     * @see dsh.messages.Envelope.DataEnvelope
     * @see Serdes#fromBytes(Parser, byte[])
     */
    public static Function deserializeValue = (byte[] bytes) -> Serdes.fromBytes(Envelope.DataEnvelope.parser(), bytes);

    /**
     * Function to serialize a KeyEnvelope
     * @see dsh.messages.Envelope.KeyEnvelope
     * @see Serdes#toBytes(Message)
     */
    public static Function serializeKey = Serdes::toBytes;

    /**
     * Function to serialize a DataEnvelope
     * @see dsh.messages.Envelope.DataEnvelope
     * @see Serdes#toBytes(Message)
     */
    public static Function serializeValue = Serdes::toBytes;
}