diff --git a/energyml-utils/example/main.py b/energyml-utils/example/main.py
index 2572f3e..ce7f6a4 100644
--- a/energyml-utils/example/main.py
+++ b/energyml-utils/example/main.py
@@ -28,7 +28,7 @@
     correct_dor,
 )
 from src.energyml.utils.xml import *
-from src.energyml.utils.data.datasets_io import HDF5FileReader
+from src.energyml.utils.data.datasets_io import HDF5FileReader, get_path_in_external_with_path
 
 fi_cit = Citation(
     title="An interpretation",
@@ -378,6 +378,7 @@ def test_local_depth_crs():
 
 def test_crs():
     from energyml.eml.v2_3.commonv2 import LocalEngineeringCompoundCrs
+
     crs = random_value_from_class(LocalEngineeringCompoundCrs)
     print(is_z_reversed(crs))
 
diff --git a/energyml-utils/example/tools.py b/energyml-utils/example/tools.py
index 4d6d252..ffef0d1 100644
--- a/energyml-utils/example/tools.py
+++ b/energyml-utils/example/tools.py
@@ -10,10 +10,19 @@
 from src.energyml.utils.data.datasets_io import CSVFileReader, HDF5FileWriter, ParquetFileWriter, DATFileReader
 from src.energyml.utils.data.mesh import MeshFileFormat, export_multiple_data
 from src.energyml.utils.epc import Epc, gen_energyml_object_path
-from src.energyml.utils.introspection import get_class_from_simple_name, random_value_from_class, \
-    set_attribute_from_path, get_object_attribute, get_qualified_type_from_class, get_content_type_from_class, \
-    get_object_attribute_rgx, get_direct_dor_list, get_obj_uuid, get_class_from_qualified_type, \
-    get_object_attribute_or_create
+from src.energyml.utils.introspection import (
+    get_class_from_simple_name,
+    random_value_from_class,
+    set_attribute_from_path,
+    get_object_attribute,
+    get_qualified_type_from_class,
+    get_content_type_from_class,
+    get_object_attribute_rgx,
+    get_direct_dor_list,
+    get_obj_uuid,
+    get_class_from_qualified_type,
+    get_object_attribute_or_create,
+)
 from src.energyml.utils.serialization import (
     serialize_json,
     JSON_VERSION,
@@ -370,6 +379,7 @@ def xml_to_json():
             json_content = serialize_json(objs, JSON_VERSION.OSDU_OFFICIAL)
     elif args.file.lower().endswith(".epc"):
         epc = Epc.read_file(args.file)
+        # print(epc.energyml_objects)
         json_content = (
             "[\n"
             + ",".join(list(map(lambda o: serialize_json(o, JSON_VERSION.OSDU_OFFICIAL), epc.energyml_objects)))
@@ -377,7 +387,9 @@ def xml_to_json():
         )
 
     with open(output_path, "w") as fout:
-        fout.write(json_content)
+        # print(json_content)
+        if json_content is not None:
+            fout.write(json_content)
 
 
 def json_to_xml():
@@ -403,6 +415,29 @@ def json_to_xml():
                 fout.write(xml_content)
 
 
+def json_to_epc():
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--file", "-f", type=str, help="Input File")
+    parser.add_argument("--out", "-o", type=str, default=None, help=f"Output EPC file")
+
+    args = parser.parse_args()
+
+    epc = Epc(epc_file_path=args.out)
+    with open(args.file, "rb") as f:
+        f_content = f.read()
+        objs = []
+        try:
+            objs = read_energyml_json_bytes(f_content, JSON_VERSION.OSDU_OFFICIAL)
+        except:
+            objs = read_energyml_json_bytes(f_content, JSON_VERSION.XSDATA)
+
+        dir = pathlib.Path(args.out or args.file).parent.resolve()
+        for obj in objs:
+            epc.energyml_objects.append(obj)
+
+    epc.export_file(args.out)
+
+
 def describe_as_csv():
     parser = argparse.ArgumentParser()
     parser.add_argument("--folder", "-f", type=str, help="Input File")
diff --git a/energyml-utils/pyproject.toml b/energyml-utils/pyproject.toml
index 288ff72..88cae1d 100644
--- a/energyml-utils/pyproject.toml
+++ b/energyml-utils/pyproject.toml
@@ -128,4 +128,5 @@ csv_to_dataset = "example.tools:csv_to_dataset"
 generate_data = "example.tools:generate_data"
 xml_to_json = "example.tools:xml_to_json"
 json_to_xml = "example.tools:json_to_xml"
+json_to_epc = "example.tools:json_to_epc"
 describe_as_csv = "example.tools:describe_as_csv"
\ No newline at end of file
diff --git a/energyml-utils/src/energyml/utils/constants.py b/energyml-utils/src/energyml/utils/constants.py
index e134381..5a3928b 100644
--- a/energyml-utils/src/energyml/utils/constants.py
+++ b/energyml-utils/src/energyml/utils/constants.py
@@ -305,6 +305,23 @@ def parse_content_or_qualified_type(cqt: str) -> Optional[re.Match[str]]:
     return parsed
 
 
+def content_type_to_qualified_type(ct: str):
+    parsed = parse_content_or_qualified_type(ct)
+    return parsed.group("domain") + parsed.group("domainVersion").replace(".", "") + "." + parsed.group("type")
+
+
+def qualified_type_to_content_type(qt: str):
+    parsed = parse_content_or_qualified_type(qt)
+    return (
+        "application/x-"
+        + parsed.group("domain")
+        + "+xml;version="
+        + re.sub(r"(\d)(\d)", r"\1.\2", parsed.group("domainVersion"))
+        + ";type="
+        + parsed.group("type")
+    )
+
+
 def get_domain_version_from_content_or_qualified_type(cqt: str) -> Optional[str]:
     """
     return a version number like "2.2" or "2.0"
diff --git a/energyml-utils/src/energyml/utils/epc.py b/energyml-utils/src/energyml/utils/epc.py
index f0899ec..ea95775 100644
--- a/energyml-utils/src/energyml/utils/epc.py
+++ b/energyml-utils/src/energyml/utils/epc.py
@@ -29,6 +29,7 @@
     Keywords1,
     TargetMode,
 )
+from .uri import parse_uri
 from xsdata.formats.dataclass.models.generics import DerivedElement
 
 from .constants import (
@@ -39,6 +40,8 @@
     RawFile,
     EPCRelsRelationshipType,
     MimeType,
+    content_type_to_qualified_type,
+    qualified_type_to_content_type,
     split_identifier,
     get_property_kind_dict_path_as_dict,
 )
@@ -49,6 +52,7 @@
 from .introspection import (
     get_class_from_content_type,
     get_obj_type,
+    is_dor,
     search_attribute_matching_type,
     get_obj_version,
     get_obj_uuid,
@@ -65,7 +69,8 @@
     set_attribute_from_path,
     set_attribute_value,
     get_object_attribute,
-    get_qualified_type_from_class, get_class_fields,
+    get_qualified_type_from_class,
+    get_class_fields,
 )
 from .manager import get_class_pkg, get_class_pkg_version
 from .serialization import (
@@ -631,32 +636,74 @@ def as_dor(obj_or_identifier: Any, dor_qualified_type: str = "eml23.DataObjectRe
     """
     dor = None
     if obj_or_identifier is not None:
-        if isinstance(obj_or_identifier, str):  # is an identifier
-            cls = get_class_from_qualified_type(dor_qualified_type)
-            dor = cls()
-            if len(__CACHE_PROP_KIND_DICT__) == 0:
-                # update the cache to check if it is a
-                update_prop_kind_dict_cache()
-            try:
-                uuid, version = split_identifier(obj_or_identifier)
-                if uuid in __CACHE_PROP_KIND_DICT__:
-                    return as_dor(__CACHE_PROP_KIND_DICT__[uuid])
-                else:
-                    set_attribute_from_path(dor, "uuid", uuid)
-                    set_attribute_from_path(dor, "ObjectVersion", version)
-            except AttributeError:
-                logging.error(f"Failed to parse identifier {obj_or_identifier}. DOR will be empty")
+        cls = get_class_from_qualified_type(dor_qualified_type)
+        dor = cls()
+        if isinstance(obj_or_identifier, str):  # is an identifier or uri
+            parsed_uri = parse_uri(obj_or_identifier)
+            if parsed_uri is not None:
+                if hasattr(dor, "qualified_type"):
+                    set_attribute_from_path(dor, "qualified_type", parsed_uri.get_qualified_type())
+                if hasattr(dor, "content_type"):
+                    set_attribute_from_path(
+                        dor, "content_type", qualified_type_to_content_type(parsed_uri.get_qualified_type())
+                    )
+                set_attribute_from_path(dor, "uuid", parsed_uri.uuid)
+                if hasattr(dor, "object_version"):
+                    set_attribute_from_path(dor, "version_string", parsed_uri.version)
+                if hasattr(dor, "version_string"):
+                    set_attribute_from_path(dor, "version_string", parsed_uri.version)
+
+            else:  # identifier
+                if len(__CACHE_PROP_KIND_DICT__) == 0:
+                    # update the cache to check if it is a
+                    try:
+                        update_prop_kind_dict_cache()
+                    except FileNotFoundError as e:
+                        logging.error(f"Failed to parse propertykind dict {e}")
+                try:
+                    uuid, version = split_identifier(obj_or_identifier)
+                    if uuid in __CACHE_PROP_KIND_DICT__:
+                        return as_dor(__CACHE_PROP_KIND_DICT__[uuid])
+                    else:
+                        set_attribute_from_path(dor, "uuid", uuid)
+                        set_attribute_from_path(dor, "ObjectVersion", version)
+                except AttributeError:
+                    logging.error(f"Failed to parse identifier {obj_or_identifier}. DOR will be empty")
         else:
-            cls = get_class_from_qualified_type(dor_qualified_type)
-            dor = cls()
-            if hasattr(dor, "qualified_type"):
-                set_attribute_from_path(dor, "qualified_type", get_qualified_type_from_class(obj_or_identifier))
-            if hasattr(dor, "content_type"):
-                set_attribute_from_path(dor, "content_type", get_content_type_from_class(obj_or_identifier))
-
-            set_attribute_from_path(dor, "uuid", get_object_attribute(obj_or_identifier, "uuid"))
-            set_attribute_from_path(dor, "object_version", get_object_attribute(obj_or_identifier, "ObjectVersion"))
-            set_attribute_from_path(dor, "title", get_object_attribute(obj_or_identifier, "Citation.Title"))
+            if is_dor(obj_or_identifier):
+                # If it is a dor, we create a dor conversionif hasattr(dor, "qualified_type"):
+                if hasattr(dor, "qualified_type"):
+                    if hasattr(obj_or_identifier, "qualified_type"):
+                        dor.qualified_type = get_object_attribute(obj_or_identifier, "qualified_type")
+                    elif hasattr(obj_or_identifier, "content_type"):
+                        dor.qualified_type = content_type_to_qualified_type(
+                            get_object_attribute(obj_or_identifier, "content_type")
+                        )
+
+                if hasattr(dor, "content_type"):
+                    if hasattr(obj_or_identifier, "qualified_type"):
+                        dor.content_type = qualified_type_to_content_type(
+                            get_object_attribute(obj_or_identifier, "qualified_type")
+                        )
+                    elif hasattr(obj_or_identifier, "content_type"):
+                        dor.content_type = get_object_attribute(obj_or_identifier, "content_type")
+
+                set_attribute_from_path(dor, "title", get_object_attribute(obj_or_identifier, "Title"))
+
+            else:
+                if hasattr(dor, "qualified_type"):
+                    set_attribute_from_path(dor, "qualified_type", get_qualified_type_from_class(obj_or_identifier))
+                if hasattr(dor, "content_type"):
+                    set_attribute_from_path(dor, "content_type", get_content_type_from_class(obj_or_identifier))
+
+                set_attribute_from_path(dor, "title", get_object_attribute(obj_or_identifier, "Citation.Title"))
+
+            set_attribute_from_path(dor, "uuid", get_obj_uuid(obj_or_identifier))
+
+            if hasattr(dor, "object_version"):
+                set_attribute_from_path(dor, "object_version", get_obj_version(obj_or_identifier))
+            if hasattr(dor, "version_string"):
+                set_attribute_from_path(dor, "version_string", get_obj_version(obj_or_identifier))
 
     return dor
 
diff --git a/energyml-utils/src/energyml/utils/introspection.py b/energyml-utils/src/energyml/utils/introspection.py
index 68cd505..0449145 100644
--- a/energyml-utils/src/energyml/utils/introspection.py
+++ b/energyml-utils/src/energyml/utils/introspection.py
@@ -7,7 +7,7 @@
 import re
 import sys
 import typing
-from dataclasses import Field
+from dataclasses import Field, field
 from enum import Enum
 from importlib import import_module
 from types import ModuleType
@@ -311,8 +311,18 @@ def get_class_fields(cls: Union[type, Any]) -> Dict[str, Field]:
     try:
         return cls.__dataclass_fields__
     except AttributeError:
-        # print(list_function_parameters_with_types(cls.__new__, True))
-        return list_function_parameters_with_types(cls.__new__, True)
+        try:
+            # print(list_function_parameters_with_types(cls.__new__, True))
+            return list_function_parameters_with_types(cls.__new__, True)
+        except AttributeError as e:
+            # For not working types like proxy type for C++ binding
+            res = {}
+            for a_name, a_type in inspect.getmembers(cls):
+                # print(f"{a_name} => {inspect.getmembers(a_type)}")
+                if not a_name.startswith("_") and not callable(getattr(cls, a_name, None)):
+                    res[a_name] = field()
+
+            return res
 
 
 def get_class_attributes(cls: Union[type, Any]) -> List[str]:
@@ -529,7 +539,7 @@ def get_object_attribute_advanced(obj: Any, attr_dot_path: str) -> Any:
         return value
 
 
-def get_object_attribute_no_verif(obj: Any, attr_name: str) -> Any:
+def get_object_attribute_no_verif(obj: Any, attr_name: str, default: Optional[Any] = None) -> Any:
     """
     Return the value of the attribute named after param :param:`attr_name` without verification (may raise an exception
     if it doesn't exists).
@@ -540,11 +550,19 @@ def get_object_attribute_no_verif(obj: Any, attr_name: str) -> Any:
     :return:
     """
     if isinstance(obj, list):
-        return obj[int(attr_name)]
+        if int(attr_name) < len(obj):
+            return obj[int(attr_name)] or default
+        else:
+            raise AttributeError(obj, name=attr_name)
     elif isinstance(obj, dict):
-        return obj[attr_name]
+        if attr_name in obj:
+            return obj.get(attr_name, default)
+        else:
+            raise AttributeError(obj, name=attr_name)
     else:
-        return getattr(obj, attr_name, None)
+        return (
+            getattr(obj, attr_name) or default
+        )  # we did not used the "default" of getattr to keep raising AttributeError
 
 
 def get_object_attribute_rgx(obj: Any, attr_dot_path_rgx: str) -> Any:
@@ -599,6 +617,14 @@ def class_match_rgx(
     return False
 
 
+def is_dor(obj: any) -> bool:
+    return (
+        "dataobjectreference" in get_obj_type(obj).lower()
+        or get_object_attribute(obj, "ContentType") is not None
+        or get_object_attribute(obj, "QualifiedType") is not None
+    )
+
+
 def search_attribute_matching_type_with_path(
     obj: Any,
     type_rgx: str,
@@ -1016,6 +1042,7 @@ def get_obj_version(obj: Any) -> str:
             return get_object_attribute_no_verif(obj, "version_string")
         except Exception:
             logging.error(f"Error with {type(obj)}")
+            return None
             # raise e
 
 
diff --git a/energyml-utils/src/energyml/utils/serialization.py b/energyml-utils/src/energyml/utils/serialization.py
index c90323c..32e830e 100644
--- a/energyml-utils/src/energyml/utils/serialization.py
+++ b/energyml-utils/src/energyml/utils/serialization.py
@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: Apache-2.0
 import json
 import logging
+import numpy as np
 import traceback
 from enum import Enum
 from io import BytesIO
@@ -448,6 +449,9 @@ def _to_json_dict_fn(
     """
     if obj is None:
         return None
+    elif isinstance(obj, float) and np.isnan(obj):
+        print("NaN found")
+        return None
     elif is_enum(obj):
         return obj.value
         # return {
diff --git a/energyml-utils/tests/test_constants.py b/energyml-utils/tests/test_constants.py
new file mode 100644
index 0000000..e0a795c
--- /dev/null
+++ b/energyml-utils/tests/test_constants.py
@@ -0,0 +1,15 @@
+from src.energyml.utils.constants import content_type_to_qualified_type, qualified_type_to_content_type
+
+
+def test_content_type_to_qualified_type():
+    assert (
+        content_type_to_qualified_type("application/x-resqml+xml;version=2.0;type=obj_FaultInterpretation")
+        == "resqml20.obj_FaultInterpretation"
+    )
+
+
+def test_qualified_type_to_content_type():
+    assert (
+        qualified_type_to_content_type("resqml20.obj_FaultInterpretation")
+        == "application/x-resqml+xml;version=2.0;type=obj_FaultInterpretation"
+    )
diff --git a/energyml-utils/tests/test_epc.py b/energyml-utils/tests/test_epc.py
index b21cf0c..51dd635 100644
--- a/energyml-utils/tests/test_epc.py
+++ b/energyml-utils/tests/test_epc.py
@@ -10,6 +10,7 @@
 from energyml.resqml.v2_2.resqmlv2 import TriangulatedSetRepresentation
 
 from src.energyml.utils.epc import (
+    as_dor,
     get_obj_identifier,
     gen_energyml_object_path,
     EpcExportVersion,
@@ -18,8 +19,10 @@
     epoch_to_date,
     epoch,
     gen_uuid,
+    get_content_type_from_class,
     get_obj_pkg_pkgv_type_uuid_version,
     get_obj_uri,
+    get_qualified_type_from_class,
 )
 
 fi_cit = Citation20(
@@ -134,3 +137,46 @@ def test_gen_energyml_object_path():
         gen_energyml_object_path(tr, EpcExportVersion.EXPANDED)
         == f"namespace_resqml22/{tr.uuid}/TriangulatedSetRepresentation_{tr.uuid}.xml"
     )
+
+
+def test_as_dor_object():
+    dor_fi = as_dor(fi)
+
+    assert dor_fi.title == fi.citation.title
+    assert dor_fi.uuid == fi.uuid
+    assert dor_fi.qualified_type == get_qualified_type_from_class(fi)
+
+
+def test_as_dor_another_dor():
+    dor_dor20 = as_dor(dor_correct20, "eml20.DataObjectReference")
+    assert dor_dor20.title == dor_correct20.title
+    assert dor_dor20.uuid == fi.uuid
+    assert dor_dor20.content_type == get_content_type_from_class(fi)
+
+    dor_dor20_bis = as_dor(dor_correct23, "eml20.DataObjectReference")
+    assert dor_dor20_bis.title == dor_correct23.title
+    assert dor_dor20_bis.uuid == fi.uuid
+    assert dor_dor20_bis.content_type == get_content_type_from_class(fi)
+
+    dor_dor23 = as_dor(dor_correct20, "eml23.DataObjectReference")
+    assert dor_dor23.title == dor_correct20.title
+    assert dor_dor23.uuid == fi.uuid
+    assert dor_dor23.qualified_type == get_qualified_type_from_class(fi)
+
+
+def test_as_dor_uri():
+    dor_dor20 = as_dor(
+        "eml:///dataspace('test')/resqml22.TriangulatedSetRepresentation(0a2ba9e1-1018-4bfd-8fec-1c8cef13fa52)",
+        "eml20.DataObjectReference",
+    )
+    assert dor_dor20.title is None
+    assert dor_dor20.uuid == "0a2ba9e1-1018-4bfd-8fec-1c8cef13fa52"
+    assert dor_dor20.content_type == "application/x-resqml+xml;version=2.2;type=TriangulatedSetRepresentation"
+
+    dor_dor23 = as_dor(
+        "eml:///dataspace('test')/resqml22.TriangulatedSetRepresentation(0a2ba9e1-1018-4bfd-8fec-1c8cef13fa52)",
+        "eml23.DataObjectReference",
+    )
+    assert dor_dor23.title is None
+    assert dor_dor23.uuid == "0a2ba9e1-1018-4bfd-8fec-1c8cef13fa52"
+    assert dor_dor23.qualified_type == "resqml22.TriangulatedSetRepresentation"