import java.io.DataInputStream;
import java.io.ByteArrayInputStream;

abstract class StoreBase {
    abstract byte[] read(int recId);
    abstract void write(int recId, byte[] data);

    DataInputStream readIS(int recId) {
        byte[] data = read(recId);
        return data==null ? null : new DataInputStream(new ByteArrayInputStream(data));
    }
}