You are viewing a plain text version of this content. The canonical link for it is here.
Posted to dev@ariatosca.apache.org by mx...@apache.org on 2017/03/30 14:39:38 UTC

[2/5] incubator-ariatosca git commit: ARIA-132-Models-cascading-deletion-raises-constraint-errors

ARIA-132-Models-cascading-deletion-raises-constraint-errors

Additional fixes:
- The relationships are now defined on both sides. we no longer use backref, but back_populates.


Project: http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/commit/2de04972
Tree: http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/tree/2de04972
Diff: http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/diff/2de04972

Branch: refs/heads/ARIA-86-Create-a-basic-Hello-World-blueprint-example
Commit: 2de049729f5d0fff50297d25a88f5eecdcf266f9
Parents: 07cbfcd
Author: max-orlov <ma...@gigaspaces.com>
Authored: Sun Mar 26 14:13:47 2017 +0300
Committer: max-orlov <ma...@gigaspaces.com>
Committed: Tue Mar 28 15:01:15 2017 +0300

----------------------------------------------------------------------
 aria/.pylintrc                                  |   2 +-
 aria/modeling/orchestration.py                  |  16 +
 aria/modeling/relationship.py                   | 222 +++--
 aria/modeling/service_changes.py                |  86 +-
 aria/modeling/service_common.py                 |   4 +
 aria/modeling/service_instance.py               | 813 +++++++++++-------
 aria/modeling/service_template.py               | 823 +++++++++++++------
 tests/orchestrator/context/test_operation.py    |   4 +-
 .../node-cellar/node-cellar.yaml                |   1 -
 9 files changed, 1299 insertions(+), 672 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/2de04972/aria/.pylintrc
----------------------------------------------------------------------
diff --git a/aria/.pylintrc b/aria/.pylintrc
index 589402f..7222605 100644
--- a/aria/.pylintrc
+++ b/aria/.pylintrc
@@ -375,7 +375,7 @@ max-attributes=20
 min-public-methods=0
 
 # Maximum number of public methods for a class (see R0904).
-max-public-methods=20
+max-public-methods=50
 
 # Maximum number of boolean expressions in a if statement
 max-bool-expr=5

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/2de04972/aria/modeling/orchestration.py
----------------------------------------------------------------------
diff --git a/aria/modeling/orchestration.py b/aria/modeling/orchestration.py
index 2d58671..a13ae87 100644
--- a/aria/modeling/orchestration.py
+++ b/aria/modeling/orchestration.py
@@ -103,9 +103,17 @@ class ExecutionBase(ModelMixin):
     workflow_name = Column(Text)
 
     @declared_attr
+    def logs(cls):
+        return relationship.one_to_many(cls, 'log')
+
+    @declared_attr
     def service(cls):
         return relationship.many_to_one(cls, 'service')
 
+    @declared_attr
+    def tasks(cls):
+        return relationship.one_to_many(cls, 'task')
+
     # region foreign keys
 
     @declared_attr
@@ -185,6 +193,10 @@ class PluginBase(ModelMixin):
 
     __tablename__ = 'plugin'
 
+    @declared_attr
+    def tasks(cls):
+        return relationship.one_to_many(cls, 'task')
+
     archive_name = Column(Text, nullable=False, index=True)
     distribution = Column(Text)
     distribution_release = Column(Text)
@@ -239,6 +251,10 @@ class TaskBase(ModelMixin):
     INFINITE_RETRIES = -1
 
     @declared_attr
+    def logs(cls):
+        return relationship.one_to_many(cls, 'log')
+
+    @declared_attr
     def node(cls):
         return relationship.many_to_one(cls, 'node')
 

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/2de04972/aria/modeling/relationship.py
----------------------------------------------------------------------
diff --git a/aria/modeling/relationship.py b/aria/modeling/relationship.py
index 70691b3..ac1de28 100644
--- a/aria/modeling/relationship.py
+++ b/aria/modeling/relationship.py
@@ -26,9 +26,10 @@ from sqlalchemy import (
 
 from ..utils import formatting
 
+NO_BACK_POP = 'NO_BACK_POP'
 
-def foreign_key(other_table,
-                nullable=False):
+
+def foreign_key(other_table, nullable=False):
     """
     Declare a foreign key property, which will also create a foreign key column in the table with
     the name of the property. By convention the property name should end in "_fk".
@@ -54,9 +55,7 @@ def foreign_key(other_table,
                   nullable=nullable)
 
 
-def one_to_one_self(model_class,
-                    fk,
-                    relationship_kwargs=None):
+def one_to_one_self(model_class, fk):
     """
     Declare a one-to-one relationship property. The property value would be an instance of the same
     model.
@@ -69,12 +68,8 @@ def one_to_one_self(model_class,
     :type model_class: type
     :param fk: Foreign key name
     :type fk: basestring
-    :param relationship_kwargs: Extra kwargs for SQLAlchemy ``relationship``
-    :type relationship_kwargs: {}
     """
 
-    relationship_kwargs = relationship_kwargs or {}
-
     remote_side = '{model_class}.{remote_column}'.format(
         model_class=model_class.__name__,
         remote_column=model_class.id_column_name()
@@ -85,20 +80,18 @@ def one_to_one_self(model_class,
         model_class=model_class.__name__,
         column=fk
     )
-
-    return relationship(
-        _get_class_for_table(model_class, model_class.__tablename__).__name__,
-        primaryjoin=primaryjoin,
-        remote_side=remote_side,
-        post_update=True,
-        **relationship_kwargs
+    return _relationship(
+        model_class,
+        model_class.__tablename__,
+        relationship_kwargs={
+            'primaryjoin': primaryjoin,
+            'remote_side': remote_side,
+            'post_update': True
+        }
     )
 
 
-def one_to_many_self(model_class,
-                     fk,
-                     dict_key=None,
-                     relationship_kwargs=None):
+def one_to_many_self(model_class, fk, dict_key=None):
     """
     Declare a one-to-many relationship property. The property value would be a list or dict of
     instances of the same model.
@@ -114,28 +107,24 @@ def one_to_many_self(model_class,
     :param dict_key: If set the value will be a dict with this key as the dict key; otherwise will
                      be a list
     :type dict_key: basestring
-    :param relationship_kwargs: Extra kwargs for SQLAlchemy ``relationship``
-    :type relationship_kwargs: {}
     """
-
-    relationship_kwargs = relationship_kwargs or {}
-
-    relationship_kwargs.setdefault('remote_side', '{model_class}.{remote_column}'.format(
-        model_class=model_class.__name__,
-        remote_column=fk
-    ))
-
-    return _relationship(model_class, model_class.__tablename__, None, relationship_kwargs,
-                         other_property=False, dict_key=dict_key)
+    return _relationship(
+        model_class,
+        model_class.__tablename__,
+        relationship_kwargs={
+            'remote_side': '{model_class}.{remote_column}'.format(
+                model_class=model_class.__name__, remote_column=fk)
+        },
+        back_populates=False,
+        dict_key=dict_key
+    )
 
 
 def one_to_one(model_class,
                other_table,
                fk=None,
                other_fk=None,
-               other_property=None,
-               relationship_kwargs=None,
-               backref_kwargs=None):
+               back_populates=None):
     """
     Declare a one-to-one relationship property. The property value would be an instance of the other
     table's model.
@@ -154,26 +143,25 @@ def one_to_one(model_class,
     :type fk: basestring
     :param other_fk: Foreign key name at the other table (no need specify if there's no ambiguity)
     :type other_fk: basestring
-    :param relationship_kwargs: Extra kwargs for SQLAlchemy ``relationship``
-    :type relationship_kwargs: {}
-    :param backref_kwargs: Extra kwargs for SQLAlchemy ``backref``
-    :type backref_kwargs: {}
+    :param back_populates: Override name of matching many-to-many property at other table; set to
+                       false to disable
+    :type back_populates: basestring|bool
     """
+    if back_populates is None:
+        back_populates = model_class.__tablename__
 
-    backref_kwargs = backref_kwargs or {}
-    backref_kwargs.setdefault('uselist', False)
-
-    return _relationship(model_class, other_table, backref_kwargs, relationship_kwargs,
-                         other_property, fk=fk, other_fk=other_fk)
+    return _relationship(model_class,
+                         other_table,
+                         fk=fk,
+                         back_populates=back_populates,
+                         other_fk=other_fk)
 
 
 def one_to_many(model_class,
                 child_table,
                 child_fk=None,
                 dict_key=None,
-                child_property=None,
-                relationship_kwargs=None,
-                backref_kwargs=None):
+                back_populates=None):
     """
     Declare a one-to-many relationship property. The property value would be a list or dict of
     instances of the child table's model.
@@ -194,29 +182,25 @@ def one_to_many(model_class,
     :param dict_key: If set the value will be a dict with this key as the dict key; otherwise will
                      be a list
     :type dict_key: basestring
-    :param child_property: Override name of matching many-to-one property at child table; set to
+    :param back_populates: Override name of matching many-to-one property at child table; set to
                            false to disable
-    :type child_property: basestring|bool
-    :param relationship_kwargs: Extra kwargs for SQLAlchemy ``relationship``
-    :type relationship_kwargs: {}
-    :param backref_kwargs: Extra kwargs for SQLAlchemy ``backref``
-    :type backref_kwargs: {}
+    :type back_populates: basestring|bool
     """
-
-    backref_kwargs = backref_kwargs or {}
-    backref_kwargs.setdefault('uselist', False)
-
-    return _relationship(model_class, child_table, backref_kwargs, relationship_kwargs,
-                         child_property, other_fk=child_fk, dict_key=dict_key)
+    if back_populates is None:
+        back_populates = model_class.__tablename__
+    return _relationship(
+        model_class,
+        child_table,
+        back_populates=back_populates,
+        other_fk=child_fk,
+        dict_key=dict_key)
 
 
 def many_to_one(model_class,
                 parent_table,
                 fk=None,
                 parent_fk=None,
-                parent_property=None,
-                relationship_kwargs=None,
-                backref_kwargs=None):
+                back_populates=None):
     """
     Declare a many-to-one relationship property. The property value would be an instance of the
     parent table's model.
@@ -236,34 +220,25 @@ def many_to_one(model_class,
     :type parent_table: basestring
     :param fk: Foreign key name at our table (no need specify if there's no ambiguity)
     :type fk: basestring
-    :param parent_property: Override name of matching one-to-many property at parent table; set to
+    :param back_populates: Override name of matching one-to-many property at parent table; set to
                             false to disable
-    :type parent_property: basestring|bool
-    :param relationship_kwargs: Extra kwargs for SQLAlchemy ``relationship``
-    :type relationship_kwargs: {}
-    :param backref_kwargs: Extra kwargs for SQLAlchemy ``backref``
-    :type backref_kwargs: {}
+    :type back_populates: basestring|bool
     """
+    if back_populates is None:
+        back_populates = formatting.pluralize(model_class.__tablename__)
 
-    if parent_property is None:
-        parent_property = formatting.pluralize(model_class.__tablename__)
-
-    backref_kwargs = backref_kwargs or {}
-    backref_kwargs.setdefault('uselist', True)
-    backref_kwargs.setdefault('lazy', 'dynamic')
-    backref_kwargs.setdefault('cascade', 'all') # delete children when parent is deleted
-
-    return _relationship(model_class, parent_table, backref_kwargs, relationship_kwargs,
-                         parent_property, fk=fk, other_fk=parent_fk)
+    return _relationship(model_class,
+                         parent_table,
+                         back_populates=back_populates,
+                         fk=fk,
+                         other_fk=parent_fk)
 
 
 def many_to_many(model_class,
                  other_table,
                  prefix=None,
                  dict_key=None,
-                 other_property=None,
-                 relationship_kwargs=None,
-                 backref_kwargs=None):
+                 other_property=None):
     """
     Declare a many-to-many relationship property. The property value would be a list or dict of
     instances of the other table's model.
@@ -280,8 +255,8 @@ def many_to_many(model_class,
 
     :param model_class: The class in which this relationship will be declared
     :type model_class: type
-    :param parent_table: Parent table name
-    :type parent_table: basestring
+    :param other_table: Parent table name
+    :type other_table: basestring
     :param prefix: Optional prefix for extra table name as well as for ``other_property``
     :type prefix: basestring
     :param dict_key: If set the value will be a dict with this key as the dict key; otherwise will
@@ -290,10 +265,6 @@ def many_to_many(model_class,
     :param other_property: Override name of matching many-to-many property at other table; set to
                            false to disable
     :type other_property: basestring|bool
-    :param relationship_kwargs: Extra kwargs for SQLAlchemy ``relationship``
-    :type relationship_kwargs: {}
-    :param backref_kwargs: Extra kwargs for SQLAlchemy ``backref``
-    :type backref_kwargs: {}
     """
 
     this_table = model_class.__tablename__
@@ -303,69 +274,68 @@ def many_to_many(model_class,
     other_column_name = '{0}_id'.format(other_table)
     other_foreign_key = '{0}.id'.format(other_table)
 
-    secondary_table = '{0}_{1}'.format(this_table, other_table)
+    secondary_table_name = '{0}_{1}'.format(this_table, other_table)
 
     if prefix is not None:
-        secondary_table = '{0}_{1}'.format(prefix, secondary_table)
+        secondary_table_name = '{0}_{1}'.format(prefix, secondary_table_name)
         if other_property is None:
             other_property = '{0}_{1}'.format(prefix, formatting.pluralize(this_table))
 
-    backref_kwargs = backref_kwargs or {}
-    backref_kwargs.setdefault('uselist', True)
-
-    relationship_kwargs = relationship_kwargs or {}
-    relationship_kwargs.setdefault('secondary', _get_secondary_table(
+    secondary_table = _get_secondary_table(
         model_class.metadata,
-        secondary_table,
+        secondary_table_name,
         this_column_name,
         other_column_name,
         this_foreign_key,
         other_foreign_key
-    ))
+    )
 
-    return _relationship(model_class, other_table, backref_kwargs, relationship_kwargs,
-                         other_property, dict_key=dict_key)
+    return _relationship(
+        model_class,
+        other_table,
+        relationship_kwargs={'secondary': secondary_table},
+        backref_kwargs={'name': other_property, 'uselist': True} if other_property else None,
+        dict_key=dict_key
+    )
 
 
-def _relationship(model_class, other_table, backref_kwargs, relationship_kwargs, other_property,
-                  fk=None, other_fk=None, dict_key=None):
+def _relationship(model_class,
+                  other_table_name,
+                  back_populates=None,
+                  backref_kwargs=None,
+                  relationship_kwargs=None,
+                  fk=None,
+                  other_fk=None,
+                  dict_key=None):
     relationship_kwargs = relationship_kwargs or {}
 
     if fk:
-        relationship_kwargs.setdefault('foreign_keys',
-                                       lambda: getattr(
-                                           _get_class_for_table(
-                                               model_class,
-                                               model_class.__tablename__),
-                                           fk))
+        relationship_kwargs.setdefault(
+            'foreign_keys',
+            lambda: getattr(_get_class_for_table(model_class, model_class.__tablename__), fk)
+        )
 
     elif other_fk:
-        relationship_kwargs.setdefault('foreign_keys',
-                                       lambda: getattr(
-                                           _get_class_for_table(
-                                               model_class,
-                                               other_table),
-                                           other_fk))
+        relationship_kwargs.setdefault(
+            'foreign_keys',
+            lambda: getattr(_get_class_for_table(model_class, other_table_name), other_fk)
+        )
 
     if dict_key:
         relationship_kwargs.setdefault('collection_class',
                                        attribute_mapped_collection(dict_key))
 
-    if other_property is False:
-        # No backref
-        return relationship(
-            lambda: _get_class_for_table(model_class, other_table),
-            **relationship_kwargs
-        )
+    if backref_kwargs:
+        assert back_populates is None
+        return relationship(lambda: _get_class_for_table(model_class, other_table_name),
+                            backref=backref(**backref_kwargs),
+                            **relationship_kwargs
+                           )
     else:
-        if other_property is None:
-            other_property = model_class.__tablename__
-        backref_kwargs = backref_kwargs or {}
-        return relationship(
-            lambda: _get_class_for_table(model_class, other_table),
-            backref=backref(other_property, **backref_kwargs),
-            **relationship_kwargs
-        )
+        if back_populates is not NO_BACK_POP:
+            relationship_kwargs['back_populates'] = back_populates
+        return relationship(lambda: _get_class_for_table(model_class, other_table_name),
+                            **relationship_kwargs)
 
 
 def _get_class_for_table(model_class, tablename):

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/2de04972/aria/modeling/service_changes.py
----------------------------------------------------------------------
diff --git a/aria/modeling/service_changes.py b/aria/modeling/service_changes.py
index a33e6ae..b1a75a2 100644
--- a/aria/modeling/service_changes.py
+++ b/aria/modeling/service_changes.py
@@ -42,9 +42,6 @@ class ServiceUpdateBase(ModelMixin):
     """
     Deployment update model representation.
     """
-
-    steps = None
-
     __tablename__ = 'service_update'
 
     __private_fields__ = ['service_fk',
@@ -60,14 +57,6 @@ class ServiceUpdateBase(ModelMixin):
     modified_entity_ids = Column(Dict)
     state = Column(Text)
 
-    @declared_attr
-    def execution(cls):
-        return relationship.many_to_one(cls, 'execution')
-
-    @declared_attr
-    def service(cls):
-        return relationship.many_to_one(cls, 'service', parent_property='updates')
-
     # region foreign keys
 
     @declared_attr
@@ -94,6 +83,34 @@ class ServiceUpdateBase(ModelMixin):
 
     # endregion
 
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
+
+    @declared_attr
+    def steps(cls):
+        return relationship.one_to_many(cls, 'service_update_step')
+
+    # endregion
+
+    # region many_to_one relationships
+
+    @declared_attr
+    def execution(cls):
+        return relationship.one_to_one(cls, 'execution', back_populates=relationship.NO_BACK_POP)
+
+    @declared_attr
+    def service(cls):
+        return relationship.many_to_one(cls, 'service', back_populates='updates')
+
+    # endregion
+
+    # region many_to_many relationships
+
+    # endregion
+
     def to_dict(self, suppress_error=False, **kwargs):
         dep_update_dict = super(ServiceUpdateBase, self).to_dict(suppress_error)     #pylint: disable=no-member
         # Taking care of the fact the DeploymentSteps are _BaseModels
@@ -133,10 +150,6 @@ class ServiceUpdateStepBase(ModelMixin):
     entity_id = Column(Text, nullable=False)
     entity_type = Column(Enum(*ENTITY_TYPES, name='entity_type'), nullable=False)
 
-    @declared_attr
-    def service_update(cls):
-        return relationship.many_to_one(cls, 'service_update', parent_property='steps')
-
     # region foreign keys
 
     @declared_attr
@@ -154,6 +167,26 @@ class ServiceUpdateStepBase(ModelMixin):
 
     # endregion
 
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
+
+    # endregion
+
+    # region many_to_one relationships
+
+    @declared_attr
+    def service_update(cls):
+        return relationship.many_to_one(cls, 'service_update', back_populates='steps')
+
+    # endregion
+
+    # region many_to_many relationships
+
+    # endregion
+
     def __hash__(self):
         return hash((getattr(self, self.id_column_name()), self.entity_id))
 
@@ -206,10 +239,6 @@ class ServiceModificationBase(ModelMixin):
     nodes = Column(Dict)
     status = Column(Enum(*STATES, name='service_modification_status'))
 
-    @declared_attr
-    def service(cls):
-        return relationship.many_to_one(cls, 'service', parent_property='modifications')
-
     # region foreign keys
 
     @declared_attr
@@ -226,3 +255,22 @@ class ServiceModificationBase(ModelMixin):
         return association_proxy('service', cls.name_column_name())
 
     # endregion
+
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
+
+    # endregion
+
+    # region many_to_one relationships
+    @declared_attr
+    def service(cls):
+        return relationship.many_to_one(cls, 'service', back_populates='modifications')
+
+    # endregion
+
+    # region many_to_many relationships
+
+    # endregion

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/2de04972/aria/modeling/service_common.py
----------------------------------------------------------------------
diff --git a/aria/modeling/service_common.py b/aria/modeling/service_common.py
index d6b1f33..48c3170 100644
--- a/aria/modeling/service_common.py
+++ b/aria/modeling/service_common.py
@@ -275,6 +275,10 @@ class PluginSpecificationBase(TemplateModelMixin):
 
     # endregion
 
+    @declared_attr
+    def service_template(cls):
+        return relationship.many_to_one(cls, 'service_template')
+
     @property
     def as_raw(self):
         return collections.OrderedDict((

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/2de04972/aria/modeling/service_instance.py
----------------------------------------------------------------------
diff --git a/aria/modeling/service_instance.py b/aria/modeling/service_instance.py
index 1e18db0..e2e5ae0 100644
--- a/aria/modeling/service_instance.py
+++ b/aria/modeling/service_instance.py
@@ -36,7 +36,7 @@ from . import (
 )
 
 
-class ServiceBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
+class ServiceBase(InstanceModelMixin):
     """
     A service is usually an instance of a :class:`ServiceTemplate`.
 
@@ -71,12 +71,10 @@ class ServiceBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
     :vartype created_at: :class:`datetime.datetime`
     :ivar updated_at: Update timestamp
     :vartype updated_at: :class:`datetime.datetime`
-
     :ivar permalink: ??
     :vartype permalink: basestring
     :ivar scaling_groups: ??
     :vartype scaling_groups: {}
-
     :ivar modifications: Modifications of this service
     :vartype modifications: [:class:`ServiceModification`]
     :ivar updates: Updates of this service
@@ -91,16 +89,53 @@ class ServiceBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
                           'service_template_fk',
                           'service_template_name']
 
+    # region foreign keys
+
     @declared_attr
-    def service_template(cls):
-        return relationship.many_to_one(cls, 'service_template')
+    def substitution_fk(cls):
+        """Service one-to-one to Substitution"""
+        return relationship.foreign_key('substitution', nullable=True)
 
-    description = Column(Text)
+    @declared_attr
+    def service_template_fk(cls):
+        """For Service many-to-one to ServiceTemplate"""
+        return relationship.foreign_key('service_template', nullable=True)
+
+    # endregion
+
+    # region association proxies
 
     @declared_attr
-    def meta_data(cls):
-        # Warning! We cannot use the attr name "metadata" because it's used by SQLAlchemy!
-        return relationship.many_to_many(cls, 'metadata', dict_key='name')
+    def service_template_name(cls):
+        """Required for use by SQLAlchemy queries"""
+        return association_proxy('service_template', 'name')
+
+    # endregion
+
+    # region one_to_one relationships
+
+    @declared_attr
+    def substitution(cls):
+        return relationship.one_to_one(cls, 'substitution', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region one_to_many relationships
+    @declared_attr
+    def updates(cls):
+        return relationship.one_to_many(cls, 'service_update')
+
+    @declared_attr
+    def modifications(cls):
+        return relationship.one_to_many(cls, 'service_modification')
+
+    @declared_attr
+    def executions(cls):
+        return relationship.one_to_many(cls, 'execution')
+
+    @declared_attr
+    def operations(cls):
+        return relationship.one_to_many(cls, 'operation')
 
     @declared_attr
     def nodes(cls):
@@ -115,8 +150,24 @@ class ServiceBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
         return relationship.one_to_many(cls, 'policy', dict_key='name')
 
     @declared_attr
-    def substitution(cls):
-        return relationship.one_to_one(cls, 'substitution')
+    def workflows(cls):
+        return relationship.one_to_many(cls, 'operation', dict_key='name')
+
+    # endregion
+
+    # region many_to_one relationships
+
+    @declared_attr
+    def service_template(cls):
+        return relationship.many_to_one(cls, 'service_template')
+
+    # endregion
+
+    # region many_to_many relationships
+    @declared_attr
+    def meta_data(cls):
+        # Warning! We cannot use the attr name "metadata" because it's used by SQLAlchemy!
+        return relationship.many_to_many(cls, 'metadata', dict_key='name')
 
     @declared_attr
     def inputs(cls):
@@ -127,13 +178,13 @@ class ServiceBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
         return relationship.many_to_many(cls, 'parameter', prefix='outputs', dict_key='name')
 
     @declared_attr
-    def workflows(cls):
-        return relationship.one_to_many(cls, 'operation', dict_key='name')
-
-    @declared_attr
     def plugin_specifications(cls):
         return relationship.many_to_many(cls, 'plugin_specification', dict_key='name')
 
+    # endregion
+
+    description = Column(Text)
+
     created_at = Column(DateTime, nullable=False, index=True)
     updated_at = Column(DateTime)
 
@@ -144,29 +195,6 @@ class ServiceBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
 
     # endregion
 
-    # region foreign keys
-
-    @declared_attr
-    def substitution_fk(cls):
-        """Service one-to-one to Substitution"""
-        return relationship.foreign_key('substitution', nullable=True)
-
-    @declared_attr
-    def service_template_fk(cls):
-        """For Service many-to-one to ServiceTemplate"""
-        return relationship.foreign_key('service_template', nullable=True)
-
-    # endregion
-
-    # region association proxies
-
-    @declared_attr
-    def service_template_name(cls):
-        """Required for use by SQLAlchemy queries"""
-        return association_proxy('service_template', 'name')
-
-    # endregion
-
     def satisfy_requirements(self):
         satisfied = True
         for node in self.nodes.itervalues():
@@ -290,7 +318,7 @@ class ServiceBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
                         self._dump_graph_node(target_node)
 
 
-class NodeBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
+class NodeBase(InstanceModelMixin):
     """
     Usually an instance of a :class:`NodeTemplate`.
 
@@ -318,7 +346,6 @@ class NodeBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
     :vartype inbound_relationships: [:class:`Relationship`]
     :ivar host: Host node (can be self)
     :vartype host: :class:`Node`
-
     :ivar runtime_properties: TODO: should be replaced with attributes
     :vartype runtime_properties: {}
     :ivar scaling_groups: ??
@@ -327,7 +354,6 @@ class NodeBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
     :vartype state: string
     :ivar version: Used by `aria.storage.instrumentation`
     :vartype version: int
-
     :ivar service: Containing service
     :vartype service: :class:`Service`
     :ivar groups: We are a member of these groups
@@ -391,19 +417,52 @@ class NodeBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
         except KeyError:
             return None
 
+    # region foreign_keys
+
     @declared_attr
-    def node_template(cls):
-        return relationship.many_to_one(cls, 'node_template')
+    def type_fk(cls):
+        """For Node many-to-one to Type"""
+        return relationship.foreign_key('type')
 
     @declared_attr
-    def type(cls):
-        return relationship.many_to_one(cls, 'type')
+    def host_fk(cls):
+        """For Node one-to-one to Node"""
+        return relationship.foreign_key('node', nullable=True)
 
-    description = Column(Text)
+    @declared_attr
+    def service_fk(cls):
+        """For Service one-to-many to Node"""
+        return relationship.foreign_key('service')
 
     @declared_attr
-    def properties(cls):
-        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
+    def node_template_fk(cls):
+        """For Node many-to-one to NodeTemplate"""
+        return relationship.foreign_key('node_template')
+
+    # endregion
+
+    # region association proxies
+
+    @declared_attr
+    def service_name(cls):
+        """Required for use by SQLAlchemy queries"""
+        return association_proxy('service', 'name')
+
+    # endregion
+
+    # region one_to_one relationships
+
+    @declared_attr
+    def host(cls):
+        return relationship.one_to_one_self(cls, 'host_fk')
+
+    # endregion
+
+    # region one_to_many relationships
+
+    @declared_attr
+    def tasks(cls):
+        return relationship.one_to_many(cls, 'task')
 
     @declared_attr
     def interfaces(cls):
@@ -419,20 +478,40 @@ class NodeBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
 
     @declared_attr
     def outbound_relationships(cls):
-        return relationship.one_to_many(cls, 'relationship', child_fk='source_node_fk',
-                                        child_property='source_node')
+        return relationship.one_to_many(
+            cls, 'relationship', child_fk='source_node_fk', back_populates='source_node')
 
     @declared_attr
     def inbound_relationships(cls):
-        return relationship.one_to_many(cls, 'relationship', child_fk='target_node_fk',
-                                        child_property='target_node')
+        return relationship.one_to_many(
+            cls, 'relationship', child_fk='target_node_fk', back_populates='target_node')
+
+    # endregion
+
+    # region many_to_one relationships
 
     @declared_attr
-    def host(cls):
-        return relationship.one_to_one_self(cls, 'host_fk')
+    def service(cls):
+        return relationship.many_to_one(cls, 'service')
 
-    # region orchestration
+    @declared_attr
+    def node_template(cls):
+        return relationship.many_to_one(cls, 'node_template')
+
+    @declared_attr
+    def type(cls):
+        return relationship.many_to_one(cls, 'type', back_populates=relationship.NO_BACK_POP)
 
+    # endregion
+
+    # region many_to_many relationships
+    @declared_attr
+    def properties(cls):
+        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
+
+    # endregion
+
+    description = Column(Text)
     runtime_properties = Column(modeling_types.Dict)
     scaling_groups = Column(modeling_types.List)
     state = Column(Enum(*STATES, name='node_state'), nullable=False, default=INITIAL)
@@ -454,41 +533,6 @@ class NodeBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
             return host_ip_property.value
         return None
 
-    # endregion
-
-    # region foreign_keys
-
-    @declared_attr
-    def type_fk(cls):
-        """For Node many-to-one to Type"""
-        return relationship.foreign_key('type')
-
-    @declared_attr
-    def host_fk(cls):
-        """For Node one-to-one to Node"""
-        return relationship.foreign_key('node', nullable=True)
-
-    @declared_attr
-    def service_fk(cls):
-        """For Service one-to-many to Node"""
-        return relationship.foreign_key('service')
-
-    @declared_attr
-    def node_template_fk(cls):
-        """For Node many-to-one to NodeTemplate"""
-        return relationship.foreign_key('node_template', nullable=True)
-
-    # endregion
-
-    # region association proxies
-
-    @declared_attr
-    def service_name(cls):
-        """Required for use by SQLAlchemy queries"""
-        return association_proxy('service', 'name')
-
-    # endregion
-
     def satisfy_requirements(self):
         node_template = self.node_template
         satisfied = True
@@ -513,7 +557,7 @@ class NodeBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
         from . import models
         context = ConsumptionContext.get_thread_local()
         # Find target nodes
-        target_nodes = target_node_template.nodes.all()
+        target_nodes = target_node_template.nodes
         if target_nodes:
             target_node = None
             target_capability = None
@@ -621,6 +665,7 @@ class NodeBase(InstanceModelMixin): # pylint: disable=too-many-public-methods
             utils.dump_dict_values(self.capabilities, 'Capabilities')
             utils.dump_list_values(self.outbound_relationships, 'Relationships')
 
+
 class GroupBase(InstanceModelMixin):
     """
     Usually an instance of a :class:`GroupTemplate`.
@@ -639,7 +684,6 @@ class GroupBase(InstanceModelMixin):
     :vartype properties: {basestring: :class:`Parameter`}
     :ivar interfaces: Bundles of operations
     :vartype interfaces: {basestring: :class:`Interface`}
-
     :ivar service: Containing service
     :vartype service: :class:`Service`
     :ivar policies: Policies enacted on this group
@@ -648,51 +692,73 @@ class GroupBase(InstanceModelMixin):
 
     __tablename__ = 'group'
 
-    __private_fields__ = ['type_fk',
-                          'service_fk',
-                          'group_template_fk']
+    __private_fields__ = ['type_fk', 'service_fk', 'group_template_fk']
 
-    @declared_attr
-    def group_template(cls):
-        return relationship.many_to_one(cls, 'group_template')
+    # region foreign_keys
 
     @declared_attr
-    def type(cls):
-        return relationship.many_to_one(cls, 'type')
-
-    description = Column(Text)
+    def type_fk(cls):
+        """For Group many-to-one to Type"""
+        return relationship.foreign_key('type')
 
     @declared_attr
-    def nodes(cls):
-        return relationship.many_to_many(cls, 'node')
+    def service_fk(cls):
+        """For Service one-to-many to Group"""
+        return relationship.foreign_key('service')
 
     @declared_attr
-    def properties(cls):
-        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
+    def group_template_fk(cls):
+        """For Group many-to-one to GroupTemplate"""
+        return relationship.foreign_key('group_template', nullable=True)
+
+    # endregion
+
+    # region association proxies
+
+    # endregion
+
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
 
     @declared_attr
     def interfaces(cls):
         return relationship.one_to_many(cls, 'interface', dict_key='name')
 
-    # region foreign_keys
+    # endregion
+
+    # region many_to_one relationships
 
     @declared_attr
-    def type_fk(cls):
-        """For Group many-to-one to Type"""
-        return relationship.foreign_key('type')
+    def service(cls):
+        return relationship.many_to_one(cls, 'service')
 
     @declared_attr
-    def service_fk(cls):
-        """For Service one-to-many to Group"""
-        return relationship.foreign_key('service')
+    def group_template(cls):
+        return relationship.many_to_one(cls, 'group_template')
 
     @declared_attr
-    def group_template_fk(cls):
-        """For Group many-to-one to GroupTemplate"""
-        return relationship.foreign_key('group_template', nullable=True)
+    def type(cls):
+        return relationship.many_to_one(cls, 'type', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region many_to_many relationships
+
+    @declared_attr
+    def nodes(cls):
+        return relationship.many_to_many(cls, 'node')
+
+    @declared_attr
+    def properties(cls):
+        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
 
     # endregion
 
+    description = Column(Text)
+
     @property
     def as_raw(self):
         return collections.OrderedDict((
@@ -740,58 +806,79 @@ class PolicyBase(InstanceModelMixin):
     :vartype groups: [:class:`Group`]
     :ivar properties: Associated parameters
     :vartype properties: {basestring: :class:`Parameter`}
-
     :ivar service: Containing service
     :vartype service: :class:`Service`
     """
 
     __tablename__ = 'policy'
 
-    __private_fields__ = ['type_fk',
-                          'service_fk',
-                          'policy_template_fk']
+    __private_fields__ = ['type_fk', 'service_fk', 'policy_template_fk']
 
-    @declared_attr
-    def policy_template(cls):
-        return relationship.many_to_one(cls, 'policy_template')
+    # region foreign_keys
 
     @declared_attr
-    def type(cls):
-        return relationship.many_to_one(cls, 'type')
+    def type_fk(cls):
+        """For Policy many-to-one to Type"""
+        return relationship.foreign_key('type')
 
-    description = Column(Text)
+    @declared_attr
+    def service_fk(cls):
+        """For Service one-to-many to Policy"""
+        return relationship.foreign_key('service')
 
     @declared_attr
-    def properties(cls):
-        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
+    def policy_template_fk(cls):
+        """For Policy many-to-one to PolicyTemplate"""
+        return relationship.foreign_key('policy_template', nullable=True)
+
+    # endregion
+
+    # region association proxies
+
+    # endregion
+
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
+
+    # endregion
+
+    # region many_to_one relationships
 
     @declared_attr
-    def nodes(cls):
-        return relationship.many_to_many(cls, 'node')
+    def service(cls):
+        return relationship.many_to_one(cls, 'service')
 
     @declared_attr
-    def groups(cls):
-        return relationship.many_to_many(cls, 'group')
+    def policy_template(cls):
+        return relationship.many_to_one(cls, 'policy_template')
 
-    # region foreign_keys
+    @declared_attr
+    def type(cls):
+        return relationship.many_to_one(cls, 'type', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region many_to_many relationships
 
     @declared_attr
-    def type_fk(cls):
-        """For Policy many-to-one to Type"""
-        return relationship.foreign_key('type')
+    def properties(cls):
+        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
 
     @declared_attr
-    def service_fk(cls):
-        """For Service one-to-many to Policy"""
-        return relationship.foreign_key('service')
+    def nodes(cls):
+        return relationship.many_to_many(cls, 'node')
 
     @declared_attr
-    def policy_template_fk(cls):
-        """For Policy many-to-one to PolicyTemplate"""
-        return relationship.foreign_key('policy_template', nullable=True)
+    def groups(cls):
+        return relationship.many_to_many(cls, 'group')
 
     # endregion
 
+    description = Column(Text)
+
     @property
     def as_raw(self):
         return collections.OrderedDict((
@@ -835,7 +922,6 @@ class SubstitutionBase(InstanceModelMixin):
     :vartype node_type: :class:`Type`
     :ivar mappings: Requirement and capability mappings
     :vartype mappings: {basestring: :class:`SubstitutionTemplate`}
-
     :ivar service: Containing service
     :vartype service: :class:`Service`
     """
@@ -845,29 +931,53 @@ class SubstitutionBase(InstanceModelMixin):
     __private_fields__ = ['node_type_fk',
                           'substitution_template_fk']
 
+    # region foreign_keys
+
     @declared_attr
-    def substitution_template(cls):
-        return relationship.many_to_one(cls, 'substitution_template')
+    def node_type_fk(cls):
+        """For Substitution many-to-one to Type"""
+        return relationship.foreign_key('type')
 
     @declared_attr
-    def node_type(cls):
-        return relationship.many_to_one(cls, 'type')
+    def substitution_template_fk(cls):
+        """For Substitution many-to-one to SubstitutionTemplate"""
+        return relationship.foreign_key('substitution_template', nullable=True)
+
+    # endregion
+
+    # region association proxies
+
+    # endregion
+
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
 
     @declared_attr
     def mappings(cls):
         return relationship.one_to_many(cls, 'substitution_mapping', dict_key='name')
 
-    # region foreign_keys
+    # endregion
+
+    # region many_to_one relationships
 
     @declared_attr
-    def node_type_fk(cls):
-        """For Substitution many-to-one to Type"""
-        return relationship.foreign_key('type')
+    def service(cls):
+        return relationship.one_to_one(cls, 'service', back_populates=relationship.NO_BACK_POP)
 
     @declared_attr
-    def substitution_template_fk(cls):
-        """For Substitution many-to-one to SubstitutionTemplate"""
-        return relationship.foreign_key('substitution_template', nullable=True)
+    def substitution_template(cls):
+        return relationship.many_to_one(cls, 'substitution_template')
+
+    @declared_attr
+    def node_type(cls):
+        return relationship.many_to_one(cls, 'type', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region many_to_many relationships
 
     # endregion
 
@@ -907,7 +1017,6 @@ class SubstitutionMappingBase(InstanceModelMixin):
     :vartype capability: :class:`Capability`
     :ivar requirement_template: Requirement template in the node template
     :vartype requirement_template: :class:`RequirementTemplate`
-
     :ivar substitution: Containing substitution
     :vartype substitution: :class:`Substitution`
     """
@@ -919,18 +1028,6 @@ class SubstitutionMappingBase(InstanceModelMixin):
                           'capability_fk',
                           'requirement_template_fk']
 
-    @declared_attr
-    def node(cls):
-        return relationship.one_to_one(cls, 'node')
-
-    @declared_attr
-    def capability(cls):
-        return relationship.one_to_one(cls, 'capability')
-
-    @declared_attr
-    def requirement_template(cls):
-        return relationship.one_to_one(cls, 'requirement_template')
-
     # region foreign keys
 
     @declared_attr
@@ -955,6 +1052,43 @@ class SubstitutionMappingBase(InstanceModelMixin):
 
     # endregion
 
+    # region association proxies
+
+    # endregion
+
+    # region one_to_one relationships
+
+    @declared_attr
+    def substitution(cls):
+        return relationship.many_to_one(cls, 'substitution', back_populates='mappings')
+
+    @declared_attr
+    def node(cls):
+        return relationship.one_to_one(cls, 'node', back_populates=relationship.NO_BACK_POP)
+
+    @declared_attr
+    def capability(cls):
+        return relationship.one_to_one(cls, 'capability', back_populates=relationship.NO_BACK_POP)
+
+    @declared_attr
+    def requirement_template(cls):
+        return relationship.one_to_one(
+            cls, 'requirement_template', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region one_to_many relationships
+
+    # endregion
+
+    # region many_to_one relationships
+
+    # endregion
+
+    # region many_to_many relationships
+
+    # endregion
+
     @property
     def as_raw(self):
         return collections.OrderedDict((
@@ -1002,12 +1136,10 @@ class RelationshipBase(InstanceModelMixin):
     :vartype properties: {basestring: :class:`Parameter`}
     :ivar interfaces: Bundles of operations
     :vartype interfaces: {basestring: :class:`Interfaces`}
-
     :ivar source_position: ??
     :vartype source_position: int
     :ivar target_position: ??
     :vartype target_position: int
-
     :ivar source_node: Source node
     :vartype source_node: :class:`Node`
     :ivar target_node: Target node
@@ -1027,37 +1159,6 @@ class RelationshipBase(InstanceModelMixin):
                           'source_node_name',
                           'target_node_name']
 
-    @declared_attr
-    def relationship_template(cls):
-        return relationship.many_to_one(cls, 'relationship_template')
-
-    @declared_attr
-    def requirement_template(cls):
-        return relationship.many_to_one(cls, 'requirement_template')
-
-    @declared_attr
-    def type(cls):
-        return relationship.many_to_one(cls, 'type')
-
-    @declared_attr
-    def target_capability(cls):
-        return relationship.one_to_one(cls, 'capability')
-
-    @declared_attr
-    def properties(cls):
-        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
-
-    @declared_attr
-    def interfaces(cls):
-        return relationship.one_to_many(cls, 'interface', dict_key='name')
-
-    # region orchestration
-
-    source_position = Column(Integer) # ???
-    target_position = Column(Integer) # ???
-
-    # endregion
-
     # region foreign keys
 
     @declared_attr
@@ -1106,6 +1207,63 @@ class RelationshipBase(InstanceModelMixin):
 
     # endregion
 
+    # region one_to_one relationships
+
+    @declared_attr
+    def target_capability(cls):
+        return relationship.one_to_one(cls, 'capability', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region one_to_many relationships
+
+    @declared_attr
+    def tasks(cls):
+        return relationship.one_to_many(cls, 'task')
+
+    @declared_attr
+    def interfaces(cls):
+        return relationship.one_to_many(cls, 'interface', dict_key='name')
+
+    # endregion
+
+    # region many_to_one relationships
+
+    @declared_attr
+    def source_node(cls):
+        return relationship.many_to_one(
+            cls, 'node', fk='source_node_fk', back_populates='outbound_relationships')
+
+    @declared_attr
+    def target_node(cls):
+        return relationship.many_to_one(
+            cls, 'node', fk='target_node_fk', back_populates='inbound_relationships')
+
+    @declared_attr
+    def relationship_template(cls):
+        return relationship.many_to_one(cls, 'relationship_template')
+
+    @declared_attr
+    def requirement_template(cls):
+        return relationship.many_to_one(cls, 'requirement_template')
+
+    @declared_attr
+    def type(cls):
+        return relationship.many_to_one(cls, 'type', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region many_to_many relationships
+
+    @declared_attr
+    def properties(cls):
+        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
+
+    # endregion
+
+    source_position = Column(Integer) # ???
+    target_position = Column(Integer) # ???
+
     @property
     def as_raw(self):
         return collections.OrderedDict((
@@ -1166,7 +1324,6 @@ class CapabilityBase(InstanceModelMixin):
     :vartype occurrences: int
     :ivar properties: Associated parameters
     :vartype properties: {basestring: :class:`Parameter`}
-
     :ivar node: Containing node
     :vartype node: :class:`Node`
     :ivar relationship: Available when we are the target of a relationship
@@ -1181,22 +1338,6 @@ class CapabilityBase(InstanceModelMixin):
                           'node_fk',
                           'capability_template_fk']
 
-    @declared_attr
-    def capability_template(cls):
-        return relationship.many_to_one(cls, 'capability_template')
-
-    @declared_attr
-    def type(cls):
-        return relationship.many_to_one(cls, 'type')
-
-    min_occurrences = Column(Integer, default=None)
-    max_occurrences = Column(Integer, default=None)
-    occurrences = Column(Integer, default=0)
-
-    @declared_attr
-    def properties(cls):
-        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
-
     # region foreign_keys
 
     @declared_attr
@@ -1216,6 +1357,46 @@ class CapabilityBase(InstanceModelMixin):
 
     # endregion
 
+    # region association proxies
+
+    # endregion
+
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
+
+    # endregion
+
+    # region many_to_one relationships
+
+    @declared_attr
+    def node(cls):
+        return relationship.many_to_one(cls, 'node')
+
+    @declared_attr
+    def capability_template(cls):
+        return relationship.many_to_one(cls, 'capability_template')
+
+    @declared_attr
+    def type(cls):
+        return relationship.many_to_one(cls, 'type', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region many_to_many relationships
+
+    @declared_attr
+    def properties(cls):
+        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
+
+    # endregion
+
+    min_occurrences = Column(Integer, default=None)
+    max_occurrences = Column(Integer, default=None)
+    occurrences = Column(Integer, default=0)
+
     @property
     def has_enough_relationships(self):
         if self.min_occurrences is not None:
@@ -1274,7 +1455,6 @@ class InterfaceBase(InstanceModelMixin):
     :vartype inputs: {basestring: :class:`Parameter`}
     :ivar operations: Operations
     :vartype operations: {basestring: :class:`Operation`}
-
     :ivar node: Containing node
     :vartype node: :class:`Node`
     :ivar group: Containing group
@@ -1291,24 +1471,6 @@ class InterfaceBase(InstanceModelMixin):
                           'relationship_fk',
                           'interface_template_fk']
 
-    @declared_attr
-    def interface_template(cls):
-        return relationship.many_to_one(cls, 'interface_template')
-
-    @declared_attr
-    def type(cls):
-        return relationship.many_to_one(cls, 'type')
-
-    description = Column(Text)
-
-    @declared_attr
-    def inputs(cls):
-        return relationship.many_to_many(cls, 'parameter', prefix='inputs', dict_key='name')
-
-    @declared_attr
-    def operations(cls):
-        return relationship.one_to_many(cls, 'operation', dict_key='name')
-
     # region foreign_keys
 
     @declared_attr
@@ -1338,6 +1500,56 @@ class InterfaceBase(InstanceModelMixin):
 
     # endregion
 
+    # region association proxies
+
+    # endregion
+
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
+
+    @declared_attr
+    def operations(cls):
+        return relationship.one_to_many(cls, 'operation', dict_key='name')
+
+    # endregion
+
+    # region many_to_one relationships
+
+    @declared_attr
+    def node(cls):
+        return relationship.many_to_one(cls, 'node')
+
+    @declared_attr
+    def relationship(cls):
+        return relationship.many_to_one(cls, 'relationship')
+
+    @declared_attr
+    def group(cls):
+        return relationship.many_to_one(cls, 'group')
+
+    @declared_attr
+    def interface_template(cls):
+        return relationship.many_to_one(cls, 'interface_template')
+
+    @declared_attr
+    def type(cls):
+        return relationship.many_to_one(cls, 'type', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region many_to_many relationships
+
+    @declared_attr
+    def inputs(cls):
+        return relationship.many_to_many(cls, 'parameter', prefix='inputs', dict_key='name')
+
+    # endregion
+
+    description = Column(Text)
+
     @property
     def as_raw(self):
         return collections.OrderedDict((
@@ -1392,7 +1604,6 @@ class OperationBase(InstanceModelMixin):
     :vartype max_retries: int
     :ivar retry_interval: Interval between retries (in seconds)
     :vartype retry_interval: int
-
     :ivar interface: Containing interface
     :vartype interface: :class:`Interface`
     :ivar service: Containing service
@@ -1406,27 +1617,6 @@ class OperationBase(InstanceModelMixin):
                           'plugin_fk',
                           'operation_template_fk']
 
-    @declared_attr
-    def operation_template(cls):
-        return relationship.many_to_one(cls, 'operation_template')
-
-    description = Column(Text)
-
-    @declared_attr
-    def plugin_specification(cls):
-        return relationship.one_to_one(cls, 'plugin_specification')
-
-    implementation = Column(Text)
-    dependencies = Column(modeling_types.StrictList(item_cls=basestring))
-
-    @declared_attr
-    def inputs(cls):
-        return relationship.many_to_many(cls, 'parameter', prefix='inputs', dict_key='name')
-
-    executor = Column(Text)
-    max_retries = Column(Integer)
-    retry_interval = Column(Integer)
-
     # region foreign_keys
 
     @declared_attr
@@ -1451,6 +1641,56 @@ class OperationBase(InstanceModelMixin):
 
     # endregion
 
+    # region association proxies
+
+    # endregion
+
+    # region one_to_one relationships
+
+    @declared_attr
+    def plugin_specification(cls):
+        return relationship.one_to_one(
+            cls, 'plugin_specification', back_populates=relationship.NO_BACK_POP)
+
+    # endregion
+
+    # region one_to_many relationships
+
+    # endregion
+
+    # region many_to_one relationships
+
+    @declared_attr
+    def service(cls):
+        return relationship.many_to_one(cls, 'service')
+
+    @declared_attr
+    def interface(cls):
+        return relationship.many_to_one(cls, 'interface')
+
+    @declared_attr
+    def operation_template(cls):
+        return relationship.many_to_one(cls, 'operation_template')
+
+    # endregion
+
+    # region many_to_many relationships
+
+    @declared_attr
+    def inputs(cls):
+        return relationship.many_to_many(cls, 'parameter', prefix='inputs', dict_key='name')
+
+    # endregion
+
+    description = Column(Text)
+    implementation = Column(Text)
+    dependencies = Column(modeling_types.StrictList(item_cls=basestring))
+    executor = Column(Text)
+    max_retries = Column(Integer)
+    retry_interval = Column(Integer)
+
+
+
     @property
     def as_raw(self):
         return collections.OrderedDict((
@@ -1517,7 +1757,6 @@ class ArtifactBase(InstanceModelMixin):
     :vartype repository_credential: {basestring: basestring}
     :ivar properties: Associated parameters
     :vartype properties: {basestring: :class:`Parameter`}
-
     :ivar node: Containing node
     :vartype node: :class:`Node`
     """
@@ -1528,24 +1767,6 @@ class ArtifactBase(InstanceModelMixin):
                           'node_fk',
                           'artifact_template_fk']
 
-    @declared_attr
-    def artifact_template(cls):
-        return relationship.many_to_one(cls, 'artifact_template')
-
-    @declared_attr
-    def type(cls):
-        return relationship.many_to_one(cls, 'type')
-
-    description = Column(Text)
-    source_path = Column(Text)
-    target_path = Column(Text)
-    repository_url = Column(Text)
-    repository_credential = Column(modeling_types.StrictDict(basestring, basestring))
-
-    @declared_attr
-    def properties(cls):
-        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
-
     # region foreign_keys
 
     @declared_attr
@@ -1565,6 +1786,44 @@ class ArtifactBase(InstanceModelMixin):
 
     # endregion
 
+    # region association proxies
+
+    # endregion
+
+    # region one_to_one relationships
+
+    # endregion
+
+    # region one_to_many relationships
+
+    # endregion
+
+    # region many_to_one relationships
+    @declared_attr
+    def node(cls):
+        return relationship.many_to_one(cls, 'node')
+
+    @declared_attr
+    def artifact_template(cls):
+        return relationship.many_to_one(cls, 'artifact_template')
+
+    @declared_attr
+    def type(cls):
+        return relationship.many_to_one(cls, 'type', back_populates=relationship.NO_BACK_POP)
+    # endregion
+
+    # region many_to_many relationships
+    @declared_attr
+    def properties(cls):
+        return relationship.many_to_many(cls, 'parameter', prefix='properties', dict_key='name')
+    # endregion
+
+    description = Column(Text)
+    source_path = Column(Text)
+    target_path = Column(Text)
+    repository_url = Column(Text)
+    repository_credential = Column(modeling_types.StrictDict(basestring, basestring))
+
     @property
     def as_raw(self):
         return collections.OrderedDict((