make OperationVariable a Namespace

This commit makes `OperationVariable` inherit from
`UniqueIdShortNamespace`, to implement Constraint AASd-134:

For an Operation, the idShort of all inputVariable/value,
outputVariable/value, and inoutputVariable/value shall be unique.

In the DotAAS spec, the attributes `inputVariable`, `outputVariable`
and `inoutputVariable` of `Operation` are defined to be a collection of
`OperationVariable` instances, which themselves just contain a single
`SubmodelElement`. Thus, the `OperationVariable` isn't really required
for `Operation`, as the `Operation` can just contain the
`SubmodelElements` directly, without an unnecessary wrapper. This makes
`Operation` less tedious to use and also allows us to use normal
`NamespaceSets` for the 3 attributes, which together with the
`UniqueIdShortNamespace` ensure, that the `idShort` of all contained
`SubmodelElements` is unique across all 3 attributes.

Aside this, the examples are updated since `SubmodelElements` as
children of an `Operation` are now linked to the parent. This prevents
us from reusing other `SubmodelElements` as `OperationVariables` as it
was done previously, since each `SubmodelElement` can only have one
parent.

Fix #146 #148

basyx/aas/adapter/json/json_deserialization.py

@@ -364,12 +364,14 @@ def _construct_administrative_information(
         return ret
 
     @classmethod
-    def _construct_operation_variable(
-            cls, dct: Dict[str, object], object_class=model.OperationVariable) -> model.OperationVariable:
+    def _construct_operation_variable(cls, dct: Dict[str, object]) -> model.SubmodelElement:
+        """
+        Since we don't implement `OperationVariable`, this constructor discards the wrapping `OperationVariable` object
+        and just returns the contained :class:`~aas.model.submodel.SubmodelElement`.
+        """
         # TODO: remove the following type: ignore comments when mypy supports abstract types for Type[T]
         # see https://github.com/python/mypy/issues/5374
-        ret = object_class(value=_get_ts(dct, 'value', model.SubmodelElement))  # type: ignore
-        return ret
+        return _get_ts(dct, 'value', model.SubmodelElement)  # type: ignore
 
     @classmethod
     def _construct_lang_string_set(cls, lst: List[Dict[str, object]], object_class: Type[LSS]) -> LSS:
@@ -590,7 +592,7 @@ def _construct_operation(cls, dct: Dict[str, object], object_class=model.Operati
             if json_name in dct:
                 for variable_data in _get_ts(dct, json_name, list):
                     try:
-                        target.append(cls._construct_operation_variable(variable_data))
+                        target.add(cls._construct_operation_variable(variable_data))
                     except (KeyError, TypeError) as e:
                         error_message = "Error while trying to convert JSON object into {} of {}: {}".format(
                             json_name, ret, pprint.pformat(variable_data, depth=2, width=2 ** 14, compact=True))

basyx/aas/adapter/json/json_serialization.py

@@ -79,7 +79,6 @@ def default(self, obj: object) -> object:
             model.LangStringSet: self._lang_string_set_to_json,
             model.MultiLanguageProperty: self._multi_language_property_to_json,
             model.Operation: self._operation_to_json,
-            model.OperationVariable: self._operation_variable_to_json,
             model.Property: self._property_to_json,
             model.Qualifier: self._qualifier_to_json,
             model.Range: self._range_to_json,
@@ -576,16 +575,17 @@ def _annotated_relationship_element_to_json(cls, obj: model.AnnotatedRelationshi
         return data
 
     @classmethod
-    def _operation_variable_to_json(cls, obj: model.OperationVariable) -> Dict[str, object]:
+    def _operation_variable_to_json(cls, obj: model.SubmodelElement) -> Dict[str, object]:
         """
-        serialization of an object from class OperationVariable to json
+        serialization of an object from class SubmodelElement to a json OperationVariable representation
+        Since we don't implement the `OperationVariable` class, which is just a wrapper for a single
+        :class:`~aas.model.submodel.SubmodelElement`, elements are serialized as the `value` attribute of an
+        `operationVariable` object.
 
-        :param obj: object of class OperationVariable
-        :return: dict with the serialized attributes of this object
+        :param obj: object of class `SubmodelElement`
+        :return: `OperationVariable` wrapper containing the serialized `SubmodelElement`
         """
-        data = cls._abstract_classes_to_json(obj)
-        data['value'] = obj.value
-        return data
+        return {'value': obj}
 
     @classmethod
     def _operation_to_json(cls, obj: model.Operation) -> Dict[str, object]:
@@ -596,12 +596,11 @@ def _operation_to_json(cls, obj: model.Operation) -> Dict[str, object]:
         :return: dict with the serialized attributes of this object
         """
         data = cls._abstract_classes_to_json(obj)
-        if obj.input_variable:
-            data['inputVariables'] = list(obj.input_variable)
-        if obj.output_variable:
-            data['outputVariables'] = list(obj.output_variable)
-        if obj.in_output_variable:
-            data['inoutputVariables'] = list(obj.in_output_variable)
+        for tag, nss in (('inputVariables', obj.input_variable),
+                         ('outputVariables', obj.output_variable),
+                         ('inoutputVariables', obj.in_output_variable)):
+            if nss:
+                data[tag] = [cls._operation_variable_to_json(obj) for obj in nss]
         return data
 
     @classmethod

basyx/aas/adapter/xml/xml_deserialization.py

@@ -533,6 +533,20 @@ def _construct_referable_reference(cls, element: etree.Element, **kwargs: Any) \
         # see https://github.com/python/mypy/issues/5374
         return cls.construct_model_reference_expect_type(element, model.Referable, **kwargs)  # type: ignore
 
+    @classmethod
+    def _construct_operation_variable(cls, element: etree.Element, **kwargs: Any) -> model.SubmodelElement:
+        """
+        Since we don't implement `OperationVariable`, this constructor discards the wrapping `aas:operationVariable`
+        and `aas:value` and just returns the contained :class:`~aas.model.submodel.SubmodelElement`.
+        """
+        value = _get_child_mandatory(element, NS_AAS + "value")
+        if len(value) == 0:
+            raise KeyError(f"{_element_pretty_identifier(value)} has no submodel element!")
+        if len(value) > 1:
+            logger.warning(f"{_element_pretty_identifier(value)} has more than one submodel element, "
+                           "using the first one...")
+        return cls.construct_submodel_element(value[0], **kwargs)
+
     @classmethod
     def construct_key(cls, element: etree.Element, object_class=model.Key, **_kwargs: Any) \
             -> model.Key:
@@ -722,19 +736,6 @@ def construct_data_element(cls, element: etree.Element, abstract_class_name: str
             raise KeyError(_element_pretty_identifier(element) + f" is not a valid {abstract_class_name}!")
         return data_elements[element.tag](element, **kwargs)
 
-    @classmethod
-    def construct_operation_variable(cls, element: etree.Element, object_class=model.OperationVariable,
-                                     **_kwargs: Any) -> model.OperationVariable:
-        value = _get_child_mandatory(element, NS_AAS + "value")
-        if len(value) == 0:
-            raise KeyError(f"{_element_pretty_identifier(value)} has no submodel element!")
-        if len(value) > 1:
-            logger.warning(f"{_element_pretty_identifier(value)} has more than one submodel element, "
-                           "using the first one...")
-        return object_class(
-            _failsafe_construct_mandatory(value[0], cls.construct_submodel_element)
-        )
-
     @classmethod
     def construct_annotated_relationship_element(cls, element: etree.Element,
                                                  object_class=model.AnnotatedRelationshipElement, **_kwargs: Any) \
@@ -856,21 +857,14 @@ def construct_multi_language_property(cls, element: etree.Element, object_class=
     def construct_operation(cls, element: etree.Element, object_class=model.Operation, **_kwargs: Any) \
             -> model.Operation:
         operation = object_class(None)
-        input_variables = element.find(NS_AAS + "inputVariables")
-        if input_variables is not None:
-            for input_variable in _child_construct_multiple(input_variables, NS_AAS + "operationVariable",
-                                                            cls.construct_operation_variable, cls.failsafe):
-                operation.input_variable.append(input_variable)
-        output_variables = element.find(NS_AAS + "outputVariables")
-        if output_variables is not None:
-            for output_variable in _child_construct_multiple(output_variables, NS_AAS + "operationVariable",
-                                                             cls.construct_operation_variable, cls.failsafe):
-                operation.output_variable.append(output_variable)
-        in_output_variables = element.find(NS_AAS + "inoutputVariables")
-        if in_output_variables is not None:
-            for in_output_variable in _child_construct_multiple(in_output_variables, NS_AAS + "operationVariable",
-                                                                cls.construct_operation_variable, cls.failsafe):
-                operation.in_output_variable.append(in_output_variable)
+        for tag, target in ((NS_AAS + "inputVariables", operation.input_variable),
+                            (NS_AAS + "outputVariables", operation.output_variable),
+                            (NS_AAS + "inoutputVariables", operation.in_output_variable)):
+            variables = element.find(tag)
+            if variables is not None:
+                for var in _child_construct_multiple(variables, NS_AAS + "operationVariable",
+                                                     cls._construct_operation_variable, cls.failsafe):
+                    target.add(var)
         cls._amend_abstract_attributes(operation, element)
         return operation
 
@@ -1236,7 +1230,6 @@ class XMLConstructables(enum.Enum):
     ADMINISTRATIVE_INFORMATION = enum.auto()
     QUALIFIER = enum.auto()
     SECURITY = enum.auto()
-    OPERATION_VARIABLE = enum.auto()
     ANNOTATED_RELATIONSHIP_ELEMENT = enum.auto()
     BASIC_EVENT_ELEMENT = enum.auto()
     BLOB = enum.auto()
@@ -1306,8 +1299,6 @@ def read_aas_xml_element(file: IO, construct: XMLConstructables, failsafe: bool
         constructor = decoder_.construct_administrative_information
     elif construct == XMLConstructables.QUALIFIER:
         constructor = decoder_.construct_qualifier
-    elif construct == XMLConstructables.OPERATION_VARIABLE:
-        constructor = decoder_.construct_operation_variable
     elif construct == XMLConstructables.ANNOTATED_RELATIONSHIP_ELEMENT:
         constructor = decoder_.construct_annotated_relationship_element
     elif construct == XMLConstructables.BASIC_EVENT_ELEMENT:

basyx/aas/adapter/xml/xml_serialization.py

@@ -726,18 +726,20 @@ def annotated_relationship_element_to_xml(obj: model.AnnotatedRelationshipElemen
     return et_annotated_relationship_element
 
 
-def operation_variable_to_xml(obj: model.OperationVariable,
-                              tag: str = NS_AAS+"operationVariable") -> etree.Element:
+def operation_variable_to_xml(obj: model.SubmodelElement, tag: str = NS_AAS+"operationVariable") -> etree.Element:
     """
-    Serialization of objects of class :class:`~aas.model.submodel.OperationVariable` to XML
+    Serialization of :class:`~aas.model.submodel.SubmodelElement` to the XML OperationVariable representation
+    Since we don't implement the `OperationVariable` class, which is just a wrapper for a single
+    :class:`~aas.model.submodel.SubmodelElement`, elements are serialized as the `aas:value` child of an
+    `aas:operationVariable` element.
 
-    :param obj: Object of class :class:`~aas.model.submodel.OperationVariable`
+    :param obj: Object of class :class:`~aas.model.submodel.SubmodelElement`
     :param tag: Namespace+Tag of the serialized element (optional). Default is "aas:operationVariable"
     :return: Serialized ElementTree object
     """
     et_operation_variable = _generate_element(tag)
     et_value = _generate_element(NS_AAS+"value")
-    et_value.append(submodel_element_to_xml(obj.value))
+    et_value.append(submodel_element_to_xml(obj))
     et_operation_variable.append(et_value)
     return et_operation_variable
 
@@ -752,21 +754,14 @@ def operation_to_xml(obj: model.Operation,
     :return: Serialized ElementTree object
     """
     et_operation = abstract_classes_to_xml(tag, obj)
-    if obj.input_variable:
-        et_input_variables = _generate_element(NS_AAS+"inputVariables")
-        for input_ov in obj.input_variable:
-            et_input_variables.append(operation_variable_to_xml(input_ov, NS_AAS+"operationVariable"))
-        et_operation.append(et_input_variables)
-    if obj.output_variable:
-        et_output_variables = _generate_element(NS_AAS+"outputVariables")
-        for output_ov in obj.output_variable:
-            et_output_variables.append(operation_variable_to_xml(output_ov, NS_AAS+"operationVariable"))
-        et_operation.append(et_output_variables)
-    if obj.in_output_variable:
-        et_inoutput_variables = _generate_element(NS_AAS+"inoutputVariables")
-        for in_out_ov in obj.in_output_variable:
-            et_inoutput_variables.append(operation_variable_to_xml(in_out_ov, NS_AAS+"operationVariable"))
-        et_operation.append(et_inoutput_variables)
+    for tag, nss in ((NS_AAS+"inputVariables", obj.input_variable),
+                     (NS_AAS+"outputVariables", obj.output_variable),
+                     (NS_AAS+"inoutputVariables", obj.in_output_variable)):
+        if nss:
+            et_variables = _generate_element(tag)
+            for submodel_element in nss:
+                et_variables.append(operation_variable_to_xml(submodel_element))
+            et_operation.append(et_variables)
     return et_operation
 
 

basyx/aas/examples/data/_helper.py

@@ -550,17 +550,6 @@ def _find_extra_elements_by_id_short(self, object_list: model.NamespaceSet, sear
                 found_elements.add(object_list_element)
         return found_elements
 
-    def _check_operation_variable_equal(self, object_: model.OperationVariable,
-                                        expected_value: model.OperationVariable):
-        """
-        Checks if the given OperationVariable objects are equal
-
-        :param object_: Given OperationVariable object to check
-        :param expected_value: expected OperationVariable object
-        :return:
-        """
-        self._check_submodel_element(object_.value, expected_value.value)
-
     def check_operation_equal(self, object_: model.Operation, expected_value: model.Operation):
         """
         Checks if the given Operation objects are equal
@@ -570,18 +559,13 @@ def check_operation_equal(self, object_: model.Operation, expected_value: model.
         :return:
         """
         self._check_abstract_attributes_submodel_element_equal(object_, expected_value)
-        self.check_contained_element_length(object_, 'input_variable', model.OperationVariable,
-                                            len(expected_value.input_variable))
-        self.check_contained_element_length(object_, 'output_variable', model.OperationVariable,
-                                            len(expected_value.output_variable))
-        self.check_contained_element_length(object_, 'in_output_variable', model.OperationVariable,
-                                            len(expected_value.in_output_variable))
-        for iv1, iv2 in zip(object_.input_variable, expected_value.input_variable):
-            self._check_operation_variable_equal(iv1, iv2)
-        for ov1, ov2 in zip(object_.output_variable, expected_value.output_variable):
-            self._check_operation_variable_equal(ov1, ov2)
-        for iov1, iov2 in zip(object_.in_output_variable, expected_value.in_output_variable):
-            self._check_operation_variable_equal(iov1, iov2)
+        for input_nss, expected_nss, attr_name in (
+                (object_.input_variable, expected_value.input_variable, 'input_variable'),
+                (object_.output_variable, expected_value.output_variable, 'output_variable'),
+                (object_.in_output_variable, expected_value.in_output_variable, 'in_output_variable')):
+            self.check_contained_element_length(object_, attr_name, model.SubmodelElement, len(expected_nss))
+            for var1, var2 in zip(input_nss, expected_nss):
+                self._check_submodel_element(var1, var2)
 
     def check_capability_equal(self, object_: model.Capability, expected_value: model.Capability):
         """

basyx/aas/examples/data/example_aas.py

@@ -557,8 +557,8 @@ def create_example_submodel() -> model.Submodel:
         embedded_data_specifications=()
     )
 
-    operation_variable_property = model.Property(
-        id_short='ExampleProperty',
+    input_variable_property = model.Property(
+        id_short='ExamplePropertyInput',
         value_type=model.datatypes.String,
         value='exampleValue',
         value_id=model.ExternalReference((model.Key(type_=model.KeyTypes.GLOBAL_REFERENCE,
@@ -570,27 +570,58 @@ def create_example_submodel() -> model.Submodel:
                                                  'de': 'Beispiel Property Element'}),
         parent=None,
         semantic_id=model.ExternalReference((model.Key(type_=model.KeyTypes.GLOBAL_REFERENCE,
-                                                       value='http://acplt.org/Properties/ExampleProperty'),)),
+                                                       value='http://acplt.org/Properties/ExamplePropertyInput'),)),
         qualifier=(),
         extension=(),
         supplemental_semantic_id=(),
         embedded_data_specifications=()
     )
 
-    submodel_element_operation_variable_input = model.OperationVariable(
-        value=operation_variable_property)
-
-    submodel_element_operation_variable_output = model.OperationVariable(
-        value=operation_variable_property)
+    output_variable_property = model.Property(
+        id_short='ExamplePropertyOutput',
+        value_type=model.datatypes.String,
+        value='exampleValue',
+        value_id=model.ExternalReference((model.Key(type_=model.KeyTypes.GLOBAL_REFERENCE,
+                                                    value='http://acplt.org/ValueId/ExampleValueId'),)),
+        display_name=model.MultiLanguageNameType({'en-US': 'ExampleProperty',
+                                                  'de': 'BeispielProperty'}),
+        category='CONSTANT',
+        description=model.MultiLanguageTextType({'en-US': 'Example Property object',
+                                                 'de': 'Beispiel Property Element'}),
+        parent=None,
+        semantic_id=model.ExternalReference((model.Key(type_=model.KeyTypes.GLOBAL_REFERENCE,
+                                                       value='http://acplt.org/Properties/ExamplePropertyOutput'),)),
+        qualifier=(),
+        extension=(),
+        supplemental_semantic_id=(),
+        embedded_data_specifications=()
+    )
 
-    submodel_element_operation_variable_in_output = model.OperationVariable(
-        value=operation_variable_property)
+    in_output_variable_property = model.Property(
+        id_short='ExamplePropertyInOutput',
+        value_type=model.datatypes.String,
+        value='exampleValue',
+        value_id=model.ExternalReference((model.Key(type_=model.KeyTypes.GLOBAL_REFERENCE,
+                                                    value='http://acplt.org/ValueId/ExampleValueId'),)),
+        display_name=model.MultiLanguageNameType({'en-US': 'ExampleProperty',
+                                                  'de': 'BeispielProperty'}),
+        category='CONSTANT',
+        description=model.MultiLanguageTextType({'en-US': 'Example Property object',
+                                                 'de': 'Beispiel Property Element'}),
+        parent=None,
+        semantic_id=model.ExternalReference((model.Key(type_=model.KeyTypes.GLOBAL_REFERENCE,
+                                                       value='http://acplt.org/Properties/ExamplePropertyInOutput'),)),
+        qualifier=(),
+        extension=(),
+        supplemental_semantic_id=(),
+        embedded_data_specifications=()
+    )
 
     submodel_element_operation = model.Operation(
         id_short='ExampleOperation',
-        input_variable=[submodel_element_operation_variable_input],
-        output_variable=[submodel_element_operation_variable_output],
-        in_output_variable=[submodel_element_operation_variable_in_output],
+        input_variable=[input_variable_property],
+        output_variable=[output_variable_property],
+        in_output_variable=[in_output_variable_property],
         category='PARAMETER',
         description=model.MultiLanguageTextType({'en-US': 'Example Operation object',
                                                  'de': 'Beispiel Operation Element'}),