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Posted to dev@ariatosca.apache.org by da...@apache.org on 2016/12/11 11:37:22 UTC

[3/5] incubator-ariatosca git commit: ARIA-30 SQL based storage implementation

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/aria/storage/models.py
----------------------------------------------------------------------
diff --git a/aria/storage/models.py b/aria/storage/models.py
index d24ad75..6302e66 100644
--- a/aria/storage/models.py
+++ b/aria/storage/models.py
@@ -36,16 +36,30 @@ classes:
     * ProviderContext - provider context implementation model.
     * Plugin - plugin implementation model.
 """
-
+from collections import namedtuple
 from datetime import datetime
-from types import NoneType
 
-from .structures import Field, IterPointerField, Model, uuid_generator, PointerField
+from sqlalchemy.ext.declarative.base import declared_attr
+
+from .structures import (
+    SQLModelBase,
+    Column,
+    Integer,
+    Text,
+    DateTime,
+    Boolean,
+    Enum,
+    String,
+    Float,
+    List,
+    Dict,
+    foreign_key,
+    one_to_many_relationship,
+    relationship_to_self,
+    orm)
 
 __all__ = (
-    'Model',
     'Blueprint',
-    'Snapshot',
     'Deployment',
     'DeploymentUpdateStep',
     'DeploymentUpdate',
@@ -59,66 +73,192 @@ __all__ = (
     'Plugin',
 )
 
-# todo: sort this, maybe move from mgr or move from aria???
-ACTION_TYPES = ()
-ENTITY_TYPES = ()
+
+#pylint: disable=no-self-argument
 
 
-class Blueprint(Model):
+class Blueprint(SQLModelBase):
     """
-    A Model which represents a blueprint
+    Blueprint model representation.
     """
-    plan = Field(type=dict)
-    id = Field(type=basestring, default=uuid_generator)
-    description = Field(type=(basestring, NoneType))
-    created_at = Field(type=datetime)
-    updated_at = Field(type=datetime)
-    main_file_name = Field(type=basestring)
+    __tablename__ = 'blueprints'
 
+    name = Column(Text, index=True)
+    created_at = Column(DateTime, nullable=False, index=True)
+    main_file_name = Column(Text, nullable=False)
+    plan = Column(Dict, nullable=False)
+    updated_at = Column(DateTime)
+    description = Column(Text)
 
-class Snapshot(Model):
+
+class Deployment(SQLModelBase):
     """
-    A Model which represents a snapshot
+    Deployment model representation.
     """
-    CREATED = 'created'
+    __tablename__ = 'deployments'
+
+    _private_fields = ['blueprint_id']
+
+    blueprint_id = foreign_key(Blueprint.id)
+
+    name = Column(Text, index=True)
+    created_at = Column(DateTime, nullable=False, index=True)
+    description = Column(Text)
+    inputs = Column(Dict)
+    groups = Column(Dict)
+    permalink = Column(Text)
+    policy_triggers = Column(Dict)
+    policy_types = Column(Dict)
+    outputs = Column(Dict)
+    scaling_groups = Column(Dict)
+    updated_at = Column(DateTime)
+    workflows = Column(Dict)
+
+    @declared_attr
+    def blueprint(cls):
+        return one_to_many_relationship(cls, Blueprint, cls.blueprint_id)
+
+
+class Execution(SQLModelBase):
+    """
+    Execution model representation.
+    """
+    __tablename__ = 'executions'
+
+    TERMINATED = 'terminated'
     FAILED = 'failed'
-    CREATING = 'creating'
-    UPLOADED = 'uploaded'
-    END_STATES = [CREATED, FAILED, UPLOADED]
+    CANCELLED = 'cancelled'
+    PENDING = 'pending'
+    STARTED = 'started'
+    CANCELLING = 'cancelling'
+    FORCE_CANCELLING = 'force_cancelling'
 
-    id = Field(type=basestring, default=uuid_generator)
-    created_at = Field(type=datetime)
-    status = Field(type=basestring)
-    error = Field(type=basestring, default=None)
+    STATES = [TERMINATED, FAILED, CANCELLED, PENDING, STARTED, CANCELLING, FORCE_CANCELLING]
+    END_STATES = [TERMINATED, FAILED, CANCELLED]
+    ACTIVE_STATES = [state for state in STATES if state not in END_STATES]
 
+    VALID_TRANSITIONS = {
+        PENDING: [STARTED, CANCELLED],
+        STARTED: END_STATES + [CANCELLING],
+        CANCELLING: END_STATES
+    }
 
-class Deployment(Model):
+    @orm.validates('status')
+    def validate_status(self, key, value):
+        """Validation function that verifies execution status transitions are OK"""
+        try:
+            current_status = getattr(self, key)
+        except AttributeError:
+            return
+        valid_transitions = Execution.VALID_TRANSITIONS.get(current_status, [])
+        if all([current_status is not None,
+                current_status != value,
+                value not in valid_transitions]):
+            raise ValueError('Cannot change execution status from {current} to {new}'.format(
+                current=current_status,
+                new=value))
+        return value
+
+    deployment_id = foreign_key(Deployment.id)
+    blueprint_id = foreign_key(Blueprint.id)
+    _private_fields = ['deployment_id', 'blueprint_id']
+
+    created_at = Column(DateTime, index=True)
+    started_at = Column(DateTime, nullable=True, index=True)
+    ended_at = Column(DateTime, nullable=True, index=True)
+    error = Column(Text, nullable=True)
+    is_system_workflow = Column(Boolean, nullable=False, default=False)
+    parameters = Column(Dict)
+    status = Column(Enum(*STATES, name='execution_status'), default=PENDING)
+    workflow_name = Column(Text, nullable=False)
+
+    @declared_attr
+    def deployment(cls):
+        return one_to_many_relationship(cls, Deployment, cls.deployment_id)
+
+    @declared_attr
+    def blueprint(cls):
+        return one_to_many_relationship(cls, Blueprint, cls.blueprint_id)
+
+    def __str__(self):
+        return '<{0} id=`{1}` (status={2})>'.format(
+            self.__class__.__name__,
+            self.id,
+            self.status
+        )
+
+
+class DeploymentUpdate(SQLModelBase):
     """
-    A Model which represents a deployment
+    Deployment update model representation.
     """
-    id = Field(type=basestring, default=uuid_generator)
-    description = Field(type=(basestring, NoneType))
-    created_at = Field(type=datetime)
-    updated_at = Field(type=datetime)
-    blueprint_id = Field(type=basestring)
-    workflows = Field(type=dict)
-    inputs = Field(type=dict, default=lambda: {})
-    policy_types = Field(type=dict, default=lambda: {})
-    policy_triggers = Field(type=dict, default=lambda: {})
-    groups = Field(type=dict, default=lambda: {})
-    outputs = Field(type=dict, default=lambda: {})
-    scaling_groups = Field(type=dict, default=lambda: {})
-
-
-class DeploymentUpdateStep(Model):
+    __tablename__ = 'deployment_updates'
+
+    deployment_id = foreign_key(Deployment.id)
+    execution_id = foreign_key(Execution.id, nullable=True)
+    _private_fields = ['execution_id', 'deployment_id']
+
+    created_at = Column(DateTime, nullable=False, index=True)
+    deployment_plan = Column(Dict, nullable=False)
+    deployment_update_node_instances = Column(Dict)
+    deployment_update_deployment = Column(Dict)
+    deployment_update_nodes = Column(Dict)
+    modified_entity_ids = Column(Dict)
+    state = Column(Text)
+
+    @declared_attr
+    def execution(cls):
+        return one_to_many_relationship(cls, Execution, cls.execution_id)
+
+    @declared_attr
+    def deployment(cls):
+        return one_to_many_relationship(cls, Deployment, cls.deployment_id)
+
+    def to_dict(self, suppress_error=False, **kwargs):
+        dep_update_dict = super(DeploymentUpdate, self).to_dict(suppress_error)
+        # Taking care of the fact the DeploymentSteps are objects
+        dep_update_dict['steps'] = [step.to_dict() for step in self.steps]
+        return dep_update_dict
+
+
+class DeploymentUpdateStep(SQLModelBase):
     """
-    A Model which represents a deployment update step
+    Deployment update step model representation.
     """
-    id = Field(type=basestring, default=uuid_generator)
-    action = Field(type=basestring, choices=ACTION_TYPES)
-    entity_type = Field(type=basestring, choices=ENTITY_TYPES)
-    entity_id = Field(type=basestring)
-    supported = Field(type=bool, default=True)
+    __tablename__ = 'deployment_update_steps'
+    _action_types = namedtuple('ACTION_TYPES', 'ADD, REMOVE, MODIFY')
+    ACTION_TYPES = _action_types(ADD='add', REMOVE='remove', MODIFY='modify')
+    _entity_types = namedtuple(
+        'ENTITY_TYPES',
+        'NODE, RELATIONSHIP, PROPERTY, OPERATION, WORKFLOW, OUTPUT, DESCRIPTION, GROUP, '
+        'POLICY_TYPE, POLICY_TRIGGER, PLUGIN')
+    ENTITY_TYPES = _entity_types(
+        NODE='node',
+        RELATIONSHIP='relationship',
+        PROPERTY='property',
+        OPERATION='operation',
+        WORKFLOW='workflow',
+        OUTPUT='output',
+        DESCRIPTION='description',
+        GROUP='group',
+        POLICY_TYPE='policy_type',
+        POLICY_TRIGGER='policy_trigger',
+        PLUGIN='plugin'
+    )
+
+    deployment_update_id = foreign_key(DeploymentUpdate.id)
+    _private_fields = ['deployment_update_id']
+
+    action = Column(Enum(*ACTION_TYPES, name='action_type'), nullable=False)
+    entity_id = Column(Text, nullable=False)
+    entity_type = Column(Enum(*ENTITY_TYPES, name='entity_type'), nullable=False)
+
+    @declared_attr
+    def deployment_update(cls):
+        return one_to_many_relationship(cls,
+                                        DeploymentUpdate,
+                                        cls.deployment_update_id,
+                                        backreference='steps')
 
     def __hash__(self):
         return hash((self.id, self.entity_id))
@@ -148,265 +288,225 @@ class DeploymentUpdateStep(Model):
         return False
 
 
-class DeploymentUpdate(Model):
+class DeploymentModification(SQLModelBase):
     """
-    A Model which represents a deployment update
+    Deployment modification model representation.
     """
-    INITIALIZING = 'initializing'
-    SUCCESSFUL = 'successful'
-    UPDATING = 'updating'
-    FINALIZING = 'finalizing'
-    EXECUTING_WORKFLOW = 'executing_workflow'
-    FAILED = 'failed'
+    __tablename__ = 'deployment_modifications'
 
-    STATES = [
-        INITIALIZING,
-        SUCCESSFUL,
-        UPDATING,
-        FINALIZING,
-        EXECUTING_WORKFLOW,
-        FAILED,
-    ]
-
-    # '{0}-{1}'.format(kwargs['deployment_id'], uuid4())
-    id = Field(type=basestring, default=uuid_generator)
-    deployment_id = Field(type=basestring)
-    state = Field(type=basestring, choices=STATES, default=INITIALIZING)
-    deployment_plan = Field()
-    deployment_update_nodes = Field(default=None)
-    deployment_update_node_instances = Field(default=None)
-    deployment_update_deployment = Field(default=None)
-    modified_entity_ids = Field(default=None)
-    execution_id = Field(type=basestring)
-    steps = IterPointerField(type=DeploymentUpdateStep, default=())
-
-
-class Execution(Model):
-    """
-    A Model which represents an execution
-    """
+    STARTED = 'started'
+    FINISHED = 'finished'
+    ROLLEDBACK = 'rolledback'
 
-    class _Validation(object):
-
-        @staticmethod
-        def execution_status_transition_validation(_, value, instance):
-            """Validation function that verifies execution status transitions are OK"""
-            try:
-                current_status = instance.status
-            except AttributeError:
-                return
-            valid_transitions = Execution.VALID_TRANSITIONS.get(current_status, [])
-            if current_status != value and value not in valid_transitions:
-                raise ValueError('Cannot change execution status from {current} to {new}'.format(
-                    current=current_status,
-                    new=value))
+    STATES = [STARTED, FINISHED, ROLLEDBACK]
+    END_STATES = [FINISHED, ROLLEDBACK]
 
-    TERMINATED = 'terminated'
-    FAILED = 'failed'
-    CANCELLED = 'cancelled'
-    PENDING = 'pending'
-    STARTED = 'started'
-    CANCELLING = 'cancelling'
-    STATES = (
-        TERMINATED,
-        FAILED,
-        CANCELLED,
-        PENDING,
-        STARTED,
-        CANCELLING,
-    )
-    END_STATES = [TERMINATED, FAILED, CANCELLED]
-    ACTIVE_STATES = [state for state in STATES if state not in END_STATES]
-    VALID_TRANSITIONS = {
-        PENDING: [STARTED, CANCELLED],
-        STARTED: END_STATES + [CANCELLING],
-        CANCELLING: END_STATES
-    }
+    deployment_id = foreign_key(Deployment.id)
+    _private_fields = ['deployment_id']
 
-    id = Field(type=basestring, default=uuid_generator)
-    status = Field(type=basestring, choices=STATES,
-                   validation_func=_Validation.execution_status_transition_validation)
-    deployment_id = Field(type=basestring)
-    workflow_id = Field(type=basestring)
-    blueprint_id = Field(type=basestring)
-    created_at = Field(type=datetime, default=datetime.utcnow)
-    started_at = Field(type=datetime, default=None)
-    ended_at = Field(type=datetime, default=None)
-    error = Field(type=basestring, default=None)
-    parameters = Field()
+    context = Column(Dict)
+    created_at = Column(DateTime, nullable=False, index=True)
+    ended_at = Column(DateTime, index=True)
+    modified_nodes = Column(Dict)
+    node_instances = Column(Dict)
+    status = Column(Enum(*STATES, name='deployment_modification_status'))
 
+    @declared_attr
+    def deployment(cls):
+        return one_to_many_relationship(cls,
+                                        Deployment,
+                                        cls.deployment_id,
+                                        backreference='modifications')
 
-class Relationship(Model):
+
+class Node(SQLModelBase):
     """
-    A Model which represents a relationship
+    Node model representation.
     """
-    id = Field(type=basestring, default=uuid_generator)
-    source_id = Field(type=basestring)
-    target_id = Field(type=basestring)
-    source_interfaces = Field(type=dict)
-    source_operations = Field(type=dict)
-    target_interfaces = Field(type=dict)
-    target_operations = Field(type=dict)
-    type = Field(type=basestring)
-    type_hierarchy = Field(type=list)
-    properties = Field(type=dict)
-
-
-class Node(Model):
+    __tablename__ = 'nodes'
+
+    # See base class for an explanation on these properties
+    is_id_unique = False
+
+    name = Column(Text, index=True)
+    _private_fields = ['deployment_id', 'host_id']
+    deployment_id = foreign_key(Deployment.id)
+    host_id = foreign_key('nodes.id', nullable=True)
+
+    @declared_attr
+    def deployment(cls):
+        return one_to_many_relationship(cls, Deployment, cls.deployment_id)
+
+    deploy_number_of_instances = Column(Integer, nullable=False)
+    # TODO: This probably should be a foreign key, but there's no guarantee
+    # in the code, currently, that the host will be created beforehand
+    max_number_of_instances = Column(Integer, nullable=False)
+    min_number_of_instances = Column(Integer, nullable=False)
+    number_of_instances = Column(Integer, nullable=False)
+    planned_number_of_instances = Column(Integer, nullable=False)
+    plugins = Column(Dict)
+    plugins_to_install = Column(Dict)
+    properties = Column(Dict)
+    operations = Column(Dict)
+    type = Column(Text, nullable=False, index=True)
+    type_hierarchy = Column(List)
+
+    @declared_attr
+    def host(cls):
+        return relationship_to_self(cls, cls.host_id, cls.id)
+
+
+class Relationship(SQLModelBase):
     """
-    A Model which represents a node
+    Relationship model representation.
     """
-    id = Field(type=basestring, default=uuid_generator)
-    blueprint_id = Field(type=basestring)
-    type = Field(type=basestring)
-    type_hierarchy = Field()
-    number_of_instances = Field(type=int)
-    planned_number_of_instances = Field(type=int)
-    deploy_number_of_instances = Field(type=int)
-    host_id = Field(type=basestring, default=None)
-    properties = Field(type=dict)
-    operations = Field(type=dict)
-    plugins = Field(type=list, default=())
-    relationships = IterPointerField(type=Relationship)
-    plugins_to_install = Field(type=list, default=())
-    min_number_of_instances = Field(type=int)
-    max_number_of_instances = Field(type=int)
-
-    def relationships_by_target(self, target_id):
-        """
-        Retreives all of the relationship by target.
-        :param target_id: the node id of the target  of the relationship
-        :yields: a relationship which target and node with the specified target_id
-        """
-        for relationship in self.relationships:
-            if relationship.target_id == target_id:
-                yield relationship
-        # todo: maybe add here Exception if isn't exists (didn't yield one's)
+    __tablename__ = 'relationships'
 
+    _private_fields = ['source_node_id', 'target_node_id']
 
-class RelationshipInstance(Model):
-    """
-    A Model which represents a relationship instance
-    """
-    id = Field(type=basestring, default=uuid_generator)
-    target_id = Field(type=basestring)
-    target_name = Field(type=basestring)
-    source_id = Field(type=basestring)
-    source_name = Field(type=basestring)
-    type = Field(type=basestring)
-    relationship = PointerField(type=Relationship)
+    source_node_id = foreign_key(Node.id)
+    target_node_id = foreign_key(Node.id)
+
+    @declared_attr
+    def source_node(cls):
+        return one_to_many_relationship(cls,
+                                        Node,
+                                        cls.source_node_id,
+                                        'outbound_relationships')
+
+    @declared_attr
+    def target_node(cls):
+        return one_to_many_relationship(cls,
+                                        Node,
+                                        cls.target_node_id,
+                                        'inbound_relationships')
 
+    source_interfaces = Column(Dict)
+    source_operations = Column(Dict, nullable=False)
+    target_interfaces = Column(Dict)
+    target_operations = Column(Dict, nullable=False)
+    type = Column(String, nullable=False)
+    type_hierarchy = Column(List)
+    properties = Column(Dict)
 
-class NodeInstance(Model):
+
+class NodeInstance(SQLModelBase):
     """
-    A Model which represents a node instance
+    Node instance model representation.
     """
-    # todo: add statuses
-    UNINITIALIZED = 'uninitialized'
-    INITIALIZING = 'initializing'
-    CREATING = 'creating'
-    CONFIGURING = 'configuring'
-    STARTING = 'starting'
-    DELETED = 'deleted'
-    STOPPING = 'stopping'
-    DELETING = 'deleting'
-    STATES = (
-        UNINITIALIZED,
-        INITIALIZING,
-        CREATING,
-        CONFIGURING,
-        STARTING,
-        DELETED,
-        STOPPING,
-        DELETING
-    )
+    __tablename__ = 'node_instances'
 
-    id = Field(type=basestring, default=uuid_generator)
-    deployment_id = Field(type=basestring)
-    runtime_properties = Field(type=dict)
-    state = Field(type=basestring, choices=STATES, default=UNINITIALIZED)
-    version = Field(type=(basestring, NoneType))
-    relationship_instances = IterPointerField(type=RelationshipInstance)
-    node = PointerField(type=Node)
-    host_id = Field(type=basestring, default=None)
-    scaling_groups = Field(default=())
-
-    def relationships_by_target(self, target_id):
-        """
-        Retreives all of the relationship by target.
-        :param target_id: the instance id of the target of the relationship
-        :yields: a relationship instance which target and node with the specified target_id
-        """
-        for relationship_instance in self.relationship_instances:
-            if relationship_instance.target_id == target_id:
-                yield relationship_instance
-        # todo: maybe add here Exception if isn't exists (didn't yield one's)
+    node_id = foreign_key(Node.id)
+    deployment_id = foreign_key(Deployment.id)
+    host_id = foreign_key('node_instances.id', nullable=True)
+
+    _private_fields = ['node_id', 'host_id']
+
+    name = Column(Text, index=True)
+    runtime_properties = Column(Dict)
+    scaling_groups = Column(Dict)
+    state = Column(Text, nullable=False)
+    version = Column(Integer, default=1)
+
+    @declared_attr
+    def deployment(cls):
+        return one_to_many_relationship(cls, Deployment, cls.deployment_id)
+
+    @declared_attr
+    def node(cls):
+        return one_to_many_relationship(cls, Node, cls.node_id)
 
+    @declared_attr
+    def host(cls):
+        return relationship_to_self(cls, cls.host_id, cls.id)
 
-class DeploymentModification(Model):
+
+class RelationshipInstance(SQLModelBase):
     """
-    A Model which represents a deployment modification
+    Relationship instance model representation.
     """
-    STARTED = 'started'
-    FINISHED = 'finished'
-    ROLLEDBACK = 'rolledback'
-    END_STATES = [FINISHED, ROLLEDBACK]
+    __tablename__ = 'relationship_instances'
+
+    relationship_id = foreign_key(Relationship.id)
+    source_node_instance_id = foreign_key(NodeInstance.id)
+    target_node_instance_id = foreign_key(NodeInstance.id)
+
+    _private_fields = ['relationship_storage_id',
+                       'source_node_instance_id',
+                       'target_node_instance_id']
 
-    id = Field(type=basestring, default=uuid_generator)
-    deployment_id = Field(type=basestring)
-    modified_nodes = Field(type=(dict, NoneType))
-    added_and_related = IterPointerField(type=NodeInstance)
-    removed_and_related = IterPointerField(type=NodeInstance)
-    extended_and_related = IterPointerField(type=NodeInstance)
-    reduced_and_related = IterPointerField(type=NodeInstance)
-    # before_modification = IterPointerField(type=NodeInstance)
-    status = Field(type=basestring, choices=(STARTED, FINISHED, ROLLEDBACK))
-    created_at = Field(type=datetime)
-    ended_at = Field(type=(datetime, NoneType))
-    context = Field()
-
-
-class ProviderContext(Model):
+    @declared_attr
+    def source_node_instance(cls):
+        return one_to_many_relationship(cls,
+                                        NodeInstance,
+                                        cls.source_node_instance_id,
+                                        'outbound_relationship_instances')
+
+    @declared_attr
+    def target_node_instance(cls):
+        return one_to_many_relationship(cls,
+                                        NodeInstance,
+                                        cls.target_node_instance_id,
+                                        'inbound_relationship_instances')
+
+    @declared_attr
+    def relationship(cls):
+        return one_to_many_relationship(cls, Relationship, cls.relationship_id)
+
+
+class ProviderContext(SQLModelBase):
     """
-    A Model which represents a provider context
+    Provider context model representation.
     """
-    id = Field(type=basestring, default=uuid_generator)
-    context = Field(type=dict)
-    name = Field(type=basestring)
+    __tablename__ = 'provider_context'
+
+    name = Column(Text, nullable=False)
+    context = Column(Dict, nullable=False)
 
 
-class Plugin(Model):
+class Plugin(SQLModelBase):
     """
-    A Model which represents a plugin
+    Plugin model representation.
     """
-    id = Field(type=basestring, default=uuid_generator)
-    package_name = Field(type=basestring)
-    archive_name = Field(type=basestring)
-    package_source = Field(type=dict)
-    package_version = Field(type=basestring)
-    supported_platform = Field(type=basestring)
-    distribution = Field(type=basestring)
-    distribution_version = Field(type=basestring)
-    distribution_release = Field(type=basestring)
-    wheels = Field()
-    excluded_wheels = Field()
-    supported_py_versions = Field(type=list)
-    uploaded_at = Field(type=datetime)
-
-
-class Task(Model):
+    __tablename__ = 'plugins'
+
+    archive_name = Column(Text, nullable=False, index=True)
+    distribution = Column(Text)
+    distribution_release = Column(Text)
+    distribution_version = Column(Text)
+    excluded_wheels = Column(Dict)
+    package_name = Column(Text, nullable=False, index=True)
+    package_source = Column(Text)
+    package_version = Column(Text)
+    supported_platform = Column(Dict)
+    supported_py_versions = Column(Dict)
+    uploaded_at = Column(DateTime, nullable=False, index=True)
+    wheels = Column(Dict, nullable=False)
+
+
+class Task(SQLModelBase):
     """
     A Model which represents an task
     """
 
-    class _Validation(object):
+    __tablename__ = 'task'
+    node_instance_id = foreign_key(NodeInstance.id, nullable=True)
+    relationship_instance_id = foreign_key(RelationshipInstance.id, nullable=True)
+    execution_id = foreign_key(Execution.id, nullable=True)
+
+    _private_fields = ['node_instance_id',
+                       'relationship_instance_id',
+                       'execution_id']
 
-        @staticmethod
-        def validate_max_attempts(_, value, *args):
-            """Validates that max attempts is either -1 or a positive number"""
-            if value < 1 and value != Task.INFINITE_RETRIES:
-                raise ValueError('Max attempts can be either -1 (infinite) or any positive number. '
-                                 'Got {value}'.format(value=value))
+    @declared_attr
+    def node_instance(cls):
+        return one_to_many_relationship(cls, NodeInstance, cls.node_instance_id)
+
+    @declared_attr
+    def relationship_instance(cls):
+        return one_to_many_relationship(cls,
+                                        RelationshipInstance,
+                                        cls.relationship_instance_id)
 
     PENDING = 'pending'
     RETRYING = 'retrying'
@@ -422,23 +522,51 @@ class Task(Model):
         SUCCESS,
         FAILED,
     )
+
     WAIT_STATES = [PENDING, RETRYING]
     END_STATES = [SUCCESS, FAILED]
+
+    @orm.validates('max_attempts')
+    def validate_max_attempts(self, _, value):                                  # pylint: disable=no-self-use
+        """Validates that max attempts is either -1 or a positive number"""
+        if value < 1 and value != Task.INFINITE_RETRIES:
+            raise ValueError('Max attempts can be either -1 (infinite) or any positive number. '
+                             'Got {value}'.format(value=value))
+        return value
+
     INFINITE_RETRIES = -1
 
-    id = Field(type=basestring, default=uuid_generator)
-    status = Field(type=basestring, choices=STATES, default=PENDING)
-    execution_id = Field(type=basestring)
-    due_at = Field(type=datetime, default=datetime.utcnow)
-    started_at = Field(type=datetime, default=None)
-    ended_at = Field(type=datetime, default=None)
-    max_attempts = Field(type=int, default=1, validation_func=_Validation.validate_max_attempts)
-    retry_count = Field(type=int, default=0)
-    retry_interval = Field(type=(int, float), default=0)
-    ignore_failure = Field(type=bool, default=False)
+    status = Column(Enum(*STATES), name='status', default=PENDING)
+
+    due_at = Column(DateTime, default=datetime.utcnow)
+    started_at = Column(DateTime, default=None)
+    ended_at = Column(DateTime, default=None)
+    max_attempts = Column(Integer, default=1)
+    retry_count = Column(Integer, default=0)
+    retry_interval = Column(Float, default=0)
+    ignore_failure = Column(Boolean, default=False)
 
     # Operation specific fields
-    name = Field(type=basestring)
-    operation_mapping = Field(type=basestring)
-    actor = Field()
-    inputs = Field(type=dict, default=lambda: {})
+    name = Column(String)
+    operation_mapping = Column(String)
+    inputs = Column(Dict)
+
+    @declared_attr
+    def execution(cls):
+        return one_to_many_relationship(cls, Execution, cls.execution_id)
+
+    @property
+    def actor(self):
+        """
+        Return the actor of the task
+        :return:
+        """
+        return self.node_instance or self.relationship_instance
+
+    @classmethod
+    def as_node_instance(cls, instance_id, **kwargs):
+        return cls(node_instance_id=instance_id, **kwargs)
+
+    @classmethod
+    def as_relationship_instance(cls, instance_id, **kwargs):
+        return cls(relationship_instance_id=instance_id, **kwargs)

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/aria/storage/sql_mapi.py
----------------------------------------------------------------------
diff --git a/aria/storage/sql_mapi.py b/aria/storage/sql_mapi.py
new file mode 100644
index 0000000..cde40c2
--- /dev/null
+++ b/aria/storage/sql_mapi.py
@@ -0,0 +1,382 @@
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+SQLAlchemy based MAPI
+"""
+
+from sqlalchemy.exc import SQLAlchemyError
+
+from aria.utils.collections import OrderedDict
+from aria.storage import (
+    api,
+    exceptions
+)
+
+
+class SQLAlchemyModelAPI(api.ModelAPI):
+    """
+    SQL based MAPI.
+    """
+
+    def __init__(self,
+                 engine,
+                 session,
+                 **kwargs):
+        super(SQLAlchemyModelAPI, self).__init__(**kwargs)
+        self._engine = engine
+        self._session = session
+
+    def get(self, entry_id, include=None, **kwargs):
+        """Return a single result based on the model class and element ID
+        """
+        query = self._get_query(include, {'id': entry_id})
+        result = query.first()
+
+        if not result:
+            raise exceptions.StorageError(
+                'Requested {0} with ID `{1}` was not found'
+                .format(self.model_cls.__name__, entry_id)
+            )
+        return result
+
+    def get_by_name(self, entry_name, include=None, **kwargs):
+        assert hasattr(self.model_cls, 'name')
+        result = self.list(include=include, filters={'name': entry_name})
+        if not result:
+            raise exceptions.StorageError(
+                'Requested {0} with NAME `{1}` was not found'
+                .format(self.model_cls.__name__, entry_name)
+            )
+        elif len(result) > 1:
+            raise exceptions.StorageError(
+                'Requested {0} with NAME `{1}` returned more than 1 value'
+                .format(self.model_cls.__name__, entry_name)
+            )
+        else:
+            return result[0]
+
+    def list(self,
+             include=None,
+             filters=None,
+             pagination=None,
+             sort=None,
+             **kwargs):
+        query = self._get_query(include, filters, sort)
+
+        results, total, size, offset = self._paginate(query, pagination)
+
+        return ListResult(
+            items=results,
+            metadata=dict(total=total,
+                          size=size,
+                          offset=offset)
+        )
+
+    def iter(self,
+             include=None,
+             filters=None,
+             sort=None,
+             **kwargs):
+        """Return a (possibly empty) list of `model_class` results
+        """
+        return iter(self._get_query(include, filters, sort))
+
+    def put(self, entry, **kwargs):
+        """Create a `model_class` instance from a serializable `model` object
+
+        :param entry: A dict with relevant kwargs, or an instance of a class
+        that has a `to_dict` method, and whose attributes match the columns
+        of `model_class` (might also my just an instance of `model_class`)
+        :return: An instance of `model_class`
+        """
+        self._session.add(entry)
+        self._safe_commit()
+        return entry
+
+    def delete(self, entry, **kwargs):
+        """Delete a single result based on the model class and element ID
+        """
+        self._load_relationships(entry)
+        self._session.delete(entry)
+        self._safe_commit()
+        return entry
+
+    def update(self, entry, **kwargs):
+        """Add `instance` to the DB session, and attempt to commit
+
+        :return: The updated instance
+        """
+        return self.put(entry)
+
+    def refresh(self, entry):
+        """Reload the instance with fresh information from the DB
+
+        :param entry: Instance to be re-loaded from the DB
+        :return: The refreshed instance
+        """
+        self._session.refresh(entry)
+        self._load_relationships(entry)
+        return entry
+
+    def _destroy_connection(self):
+        pass
+
+    def _establish_connection(self):
+        pass
+
+    def create(self, checkfirst=True, **kwargs):
+        self.model_cls.__table__.create(self._engine, checkfirst=checkfirst)
+
+    def drop(self):
+        """
+        Drop the table from the storage.
+        :return:
+        """
+        self.model_cls.__table__.drop(self._engine)
+
+    def _safe_commit(self):
+        """Try to commit changes in the session. Roll back if exception raised
+        Excepts SQLAlchemy errors and rollbacks if they're caught
+        """
+        try:
+            self._session.commit()
+        except (SQLAlchemyError, ValueError) as e:
+            self._session.rollback()
+            raise exceptions.StorageError('SQL Storage error: {0}'.format(str(e)))
+
+    def _get_base_query(self, include, joins):
+        """Create the initial query from the model class and included columns
+
+        :param include: A (possibly empty) list of columns to include in
+        the query
+        :return: An SQLAlchemy AppenderQuery object
+        """
+        # If only some columns are included, query through the session object
+        if include:
+            # Make sure that attributes come before association proxies
+            include.sort(key=lambda x: x.is_clause_element)
+            query = self._session.query(*include)
+        else:
+            # If all columns should be returned, query directly from the model
+            query = self._session.query(self.model_cls)
+
+        if not self._skip_joining(joins, include):
+            for join_table in joins:
+                query = query.join(join_table)
+
+        return query
+
+    @staticmethod
+    def _get_joins(model_class, columns):
+        """Get a list of all the tables on which we need to join
+
+        :param columns: A set of all columns involved in the query
+        """
+        joins = []  # Using a list instead of a set because order is important
+        for column_name in columns:
+            column = getattr(model_class, column_name)
+            while not column.is_attribute:
+                column = column.remote_attr
+                if column.is_attribute:
+                    join_class = column.class_
+                else:
+                    join_class = column.local_attr.class_
+
+                # Don't add the same class more than once
+                if join_class not in joins:
+                    joins.append(join_class)
+        return joins
+
+    @staticmethod
+    def _skip_joining(joins, include):
+        """Dealing with an edge case where the only included column comes from
+        an other table. In this case, we mustn't join on the same table again
+
+        :param joins: A list of tables on which we're trying to join
+        :param include: The list of
+        :return: True if we need to skip joining
+        """
+        if not joins:
+            return True
+        join_table_names = [t.__tablename__ for t in joins]
+
+        if len(include) != 1:
+            return False
+
+        column = include[0]
+        if column.is_clause_element:
+            table_name = column.element.table.name
+        else:
+            table_name = column.class_.__tablename__
+        return table_name in join_table_names
+
+    @staticmethod
+    def _sort_query(query, sort=None):
+        """Add sorting clauses to the query
+
+        :param query: Base SQL query
+        :param sort: An optional dictionary where keys are column names to
+        sort by, and values are the order (asc/desc)
+        :return: An SQLAlchemy AppenderQuery object
+        """
+        if sort:
+            for column, order in sort.items():
+                if order == 'desc':
+                    column = column.desc()
+                query = query.order_by(column)
+        return query
+
+    def _filter_query(self, query, filters):
+        """Add filter clauses to the query
+
+        :param query: Base SQL query
+        :param filters: An optional dictionary where keys are column names to
+        filter by, and values are values applicable for those columns (or lists
+        of such values)
+        :return: An SQLAlchemy AppenderQuery object
+        """
+        return self._add_value_filter(query, filters)
+
+    @staticmethod
+    def _add_value_filter(query, filters):
+        for column, value in filters.items():
+            if isinstance(value, (list, tuple)):
+                query = query.filter(column.in_(value))
+            else:
+                query = query.filter(column == value)
+
+        return query
+
+    def _get_query(self,
+                   include=None,
+                   filters=None,
+                   sort=None):
+        """Get an SQL query object based on the params passed
+
+        :param model_class: SQL DB table class
+        :param include: An optional list of columns to include in the query
+        :param filters: An optional dictionary where keys are column names to
+        filter by, and values are values applicable for those columns (or lists
+        of such values)
+        :param sort: An optional dictionary where keys are column names to
+        sort by, and values are the order (asc/desc)
+        :return: A sorted and filtered query with only the relevant
+        columns
+        """
+        include, filters, sort, joins = self._get_joins_and_converted_columns(
+            include, filters, sort
+        )
+
+        query = self._get_base_query(include, joins)
+        query = self._filter_query(query, filters)
+        query = self._sort_query(query, sort)
+        return query
+
+    def _get_joins_and_converted_columns(self,
+                                         include,
+                                         filters,
+                                         sort):
+        """Get a list of tables on which we need to join and the converted
+        `include`, `filters` and `sort` arguments (converted to actual SQLA
+        column/label objects instead of column names)
+        """
+        include = include or []
+        filters = filters or dict()
+        sort = sort or OrderedDict()
+
+        all_columns = set(include) | set(filters.keys()) | set(sort.keys())
+        joins = self._get_joins(self.model_cls, all_columns)
+
+        include, filters, sort = self._get_columns_from_field_names(
+            include, filters, sort
+        )
+        return include, filters, sort, joins
+
+    def _get_columns_from_field_names(self,
+                                      include,
+                                      filters,
+                                      sort):
+        """Go over the optional parameters (include, filters, sort), and
+        replace column names with actual SQLA column objects
+        """
+        include = [self._get_column(c) for c in include]
+        filters = dict((self._get_column(c), filters[c]) for c in filters)
+        sort = OrderedDict((self._get_column(c), sort[c]) for c in sort)
+
+        return include, filters, sort
+
+    def _get_column(self, column_name):
+        """Return the column on which an action (filtering, sorting, etc.)
+        would need to be performed. Can be either an attribute of the class,
+        or an association proxy linked to a relationship the class has
+        """
+        column = getattr(self.model_cls, column_name)
+        if column.is_attribute:
+            return column
+        else:
+            # We need to get to the underlying attribute, so we move on to the
+            # next remote_attr until we reach one
+            while not column.remote_attr.is_attribute:
+                column = column.remote_attr
+            # Put a label on the remote attribute with the name of the column
+            return column.remote_attr.label(column_name)
+
+    @staticmethod
+    def _paginate(query, pagination):
+        """Paginate the query by size and offset
+
+        :param query: Current SQLAlchemy query object
+        :param pagination: An optional dict with size and offset keys
+        :return: A tuple with four elements:
+        - res ults: `size` items starting from `offset`
+        - the total count of items
+        - `size` [default: 0]
+        - `offset` [default: 0]
+        """
+        if pagination:
+            size = pagination.get('size', 0)
+            offset = pagination.get('offset', 0)
+            total = query.order_by(None).count()  # Fastest way to count
+            results = query.limit(size).offset(offset).all()
+            return results, total, size, offset
+        else:
+            results = query.all()
+            return results, len(results), 0, 0
+
+    @staticmethod
+    def _load_relationships(instance):
+        """A helper method used to overcome a problem where the relationships
+        that rely on joins aren't being loaded automatically
+        """
+        for rel in instance.__mapper__.relationships:
+            getattr(instance, rel.key)
+
+
+class ListResult(object):
+    """
+    a ListResult contains results about the requested items.
+    """
+    def __init__(self, items, metadata):
+        self.items = items
+        self.metadata = metadata
+
+    def __len__(self):
+        return len(self.items)
+
+    def __iter__(self):
+        return iter(self.items)
+
+    def __getitem__(self, item):
+        return self.items[item]

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/aria/storage/structures.py
----------------------------------------------------------------------
diff --git a/aria/storage/structures.py b/aria/storage/structures.py
index b02366e..8dbd2a9 100644
--- a/aria/storage/structures.py
+++ b/aria/storage/structures.py
@@ -27,281 +27,218 @@ classes:
     * Model - abstract model implementation.
 """
 import json
-from itertools import count
-from uuid import uuid4
-
-from .exceptions import StorageError
-from ..logger import LoggerMixin
-from ..utils.validation import ValidatorMixin
-
-__all__ = (
-    'uuid_generator',
-    'Field',
-    'IterField',
-    'PointerField',
-    'IterPointerField',
-    'Model',
-    'Storage',
+
+from sqlalchemy.ext.mutable import Mutable
+from sqlalchemy.orm import relationship, backref
+from sqlalchemy.ext.declarative import declarative_base
+# pylint: disable=unused-import
+from sqlalchemy.ext.associationproxy import association_proxy
+from sqlalchemy import (
+    schema,
+    VARCHAR,
+    ARRAY,
+    Column,
+    Integer,
+    Text,
+    DateTime,
+    Boolean,
+    Enum,
+    String,
+    PickleType,
+    Float,
+    TypeDecorator,
+    ForeignKey,
+    orm,
 )
 
+from aria.storage import exceptions
+
+Model = declarative_base()
 
-def uuid_generator():
-    """
-    wrapper function which generates ids
-    """
-    return str(uuid4())
 
+def foreign_key(foreign_key_column, nullable=False):
+    """Return a ForeignKey object with the relevant
 
-class Field(ValidatorMixin):
+    :param foreign_key_column: Unique id column in the parent table
+    :param nullable: Should the column be allowed to remain empty
     """
-    A single field implementation
+    return Column(
+        ForeignKey(foreign_key_column, ondelete='CASCADE'),
+        nullable=nullable
+    )
+
+
+def one_to_many_relationship(child_class,
+                             parent_class,
+                             foreign_key_column,
+                             backreference=None):
+    """Return a one-to-many SQL relationship object
+    Meant to be used from inside the *child* object
+
+    :param parent_class: Class of the parent table
+    :param child_class: Class of the child table
+    :param foreign_key_column: The column of the foreign key
+    :param backreference: The name to give to the reference to the child
     """
-    NO_DEFAULT = 'NO_DEFAULT'
-
-    try:
-        # python 3 syntax
-        _next_id = count().__next__
-    except AttributeError:
-        # python 2 syntax
-        _next_id = count().next
-    _ATTRIBUTE_NAME = '_cache_{0}'.format
-
-    def __init__(
-            self,
-            type=None,
-            choices=(),
-            validation_func=None,
-            default=NO_DEFAULT,
-            **kwargs):
-        """
-        Simple field manager.
+    backreference = backreference or child_class.__tablename__
+    return relationship(
+        parent_class,
+        primaryjoin=lambda: parent_class.id == foreign_key_column,
+        # The following line make sure that when the *parent* is
+        # deleted, all its connected children are deleted as well
+        backref=backref(backreference, cascade='all')
+    )
 
-        :param type: possible type of the field.
-        :param choices: a set of possible field values.
-        :param default: default field value.
-        :param kwargs: kwargs to be passed to next in line classes.
-        """
-        self.type = type
-        self.choices = choices
-        self.default = default
-        self.validation_func = validation_func
-        super(Field, self).__init__(**kwargs)
-
-    def __get__(self, instance, owner):
-        if instance is None:
-            return self
-        field_name = self._field_name(instance)
-        try:
-            return getattr(instance, self._ATTRIBUTE_NAME(field_name))
-        except AttributeError as exc:
-            if self.default == self.NO_DEFAULT:
-                raise AttributeError(
-                    str(exc).replace(self._ATTRIBUTE_NAME(field_name), field_name))
-
-        default_value = self.default() if callable(self.default) else self.default
-        setattr(instance, self._ATTRIBUTE_NAME(field_name), default_value)
-        return default_value
-
-    def __set__(self, instance, value):
-        field_name = self._field_name(instance)
-        self.validate_value(field_name, value, instance)
-        setattr(instance, self._ATTRIBUTE_NAME(field_name), value)
-
-    def validate_value(self, name, value, instance):
-        """
-        Validates the value of the field.
 
-        :param name: the name of the field.
-        :param value: the value of the field.
-        :param instance: the instance containing the field.
-        """
-        if self.default != self.NO_DEFAULT and value == self.default:
-            return
-        if self.type:
-            self.validate_instance(name, value, self.type)
-        if self.choices:
-            self.validate_in_choice(name, value, self.choices)
-        if self.validation_func:
-            self.validation_func(name, value, instance)
-
-    def _field_name(self, instance):
-        """
-        retrieves the field name from the instance.
-
-        :param Field instance: the instance which holds the field.
-        :return: name of the field
-        :rtype: basestring
-        """
-        for name, member in vars(instance.__class__).iteritems():
-            if member is self:
-                return name
+def relationship_to_self(self_cls, parent_key, self_key):
+    return relationship(
+        self_cls,
+        foreign_keys=parent_key,
+        remote_side=self_key
+    )
 
 
-class IterField(Field):
+class _MutableType(TypeDecorator):
     """
-    Represents an iterable field.
+    Dict representation of type.
     """
-    def __init__(self, **kwargs):
-        """
-        Simple iterable field manager.
-        This field type don't have choices option.
-
-        :param kwargs: kwargs to be passed to next in line classes.
-        """
-        super(IterField, self).__init__(choices=(), **kwargs)
+    @property
+    def python_type(self):
+        raise NotImplementedError
 
-    def validate_value(self, name, values, *args):
-        """
-        Validates the value of each iterable value.
+    def process_literal_param(self, value, dialect):
+        pass
 
-        :param name: the name of the field.
-        :param values: the values of the field.
-        """
-        for value in values:
-            self.validate_instance(name, value, self.type)
+    impl = VARCHAR
 
+    def process_bind_param(self, value, dialect):
+        if value is not None:
+            value = json.dumps(value)
+        return value
 
-class PointerField(Field):
-    """
-    A single pointer field implementation.
-
-    Any PointerField points via id to another document.
-    """
+    def process_result_value(self, value, dialect):
+        if value is not None:
+            value = json.loads(value)
+        return value
 
-    def __init__(self, type, **kwargs):
-        assert issubclass(type, Model)
-        super(PointerField, self).__init__(type=type, **kwargs)
 
+class _DictType(_MutableType):
+    @property
+    def python_type(self):
+        return dict
 
-class IterPointerField(IterField, PointerField):
-    """
-    An iterable pointers field.
 
-    Any IterPointerField points via id to other documents.
-    """
-    pass
+class _ListType(_MutableType):
+    @property
+    def python_type(self):
+        return list
 
 
-class Model(object):
+class _MutableDict(Mutable, dict):
     """
-    Base class for all of the storage models.
+    Enables tracking for dict values.
     """
-    id = None
+    @classmethod
+    def coerce(cls, key, value):
+        "Convert plain dictionaries to MutableDict."
 
-    def __init__(self, **fields):
-        """
-        Abstract class for any model in the storage.
-        The Initializer creates attributes according to the (keyword arguments) that given
-        Each value is validated according to the Field.
-        Each model has to have and ID Field.
+        if not isinstance(value, _MutableDict):
+            if isinstance(value, dict):
+                return _MutableDict(value)
 
-        :param fields: each item is validated and transformed into instance attributes.
-        """
-        self._assert_model_have_id_field(**fields)
-        missing_fields, unexpected_fields = self._setup_fields(fields)
+            # this call will raise ValueError
+            try:
+                return Mutable.coerce(key, value)
+            except ValueError as e:
+                raise exceptions.StorageError('SQL Storage error: {0}'.format(str(e)))
+        else:
+            return value
 
-        if missing_fields:
-            raise StorageError(
-                'Model {name} got missing keyword arguments: {fields}'.format(
-                    name=self.__class__.__name__, fields=missing_fields))
+    def __setitem__(self, key, value):
+        "Detect dictionary set events and emit change events."
 
-        if unexpected_fields:
-            raise StorageError(
-                'Model {name} got unexpected keyword arguments: {fields}'.format(
-                    name=self.__class__.__name__, fields=unexpected_fields))
+        dict.__setitem__(self, key, value)
+        self.changed()
 
-    def __repr__(self):
-        return '{name}(fields={0})'.format(sorted(self.fields), name=self.__class__.__name__)
+    def __delitem__(self, key):
+        "Detect dictionary del events and emit change events."
 
-    def __eq__(self, other):
-        return (
-            isinstance(other, self.__class__) and
-            self.fields_dict == other.fields_dict)
+        dict.__delitem__(self, key)
+        self.changed()
 
-    @property
-    def fields(self):
-        """
-        Iterates over the fields of the model.
-        :yields: the class's field name
-        """
-        for name, field in vars(self.__class__).items():
-            if isinstance(field, Field):
-                yield name
 
-    @property
-    def fields_dict(self):
-        """
-        Transforms the instance attributes into a dict.
+class _MutableList(Mutable, list):
 
-        :return: all fields in dict format.
-        :rtype dict
-        """
-        return dict((name, getattr(self, name)) for name in self.fields)
+    @classmethod
+    def coerce(cls, key, value):
+        "Convert plain dictionaries to MutableDict."
 
-    @property
-    def json(self):
-        """
-        Transform the dict of attributes into json
-        :return:
-        """
-        return json.dumps(self.fields_dict)
+        if not isinstance(value, _MutableList):
+            if isinstance(value, list):
+                return _MutableList(value)
 
-    @classmethod
-    def _assert_model_have_id_field(cls, **fields_initializer_values):
-        if not getattr(cls, 'id', None):
-            raise StorageError('Model {cls.__name__} must have id field'.format(cls=cls))
-
-        if cls.id.default == cls.id.NO_DEFAULT and 'id' not in fields_initializer_values:
-            raise StorageError(
-                'Model {cls.__name__} is missing required '
-                'keyword-only argument: "id"'.format(cls=cls))
-
-    def _setup_fields(self, input_fields):
-        missing = []
-        for field_name in self.fields:
+            # this call will raise ValueError
             try:
-                field_obj = input_fields.pop(field_name)
-                setattr(self, field_name, field_obj)
-            except KeyError:
-                field = getattr(self.__class__, field_name)
-                if field.default == field.NO_DEFAULT:
-                    missing.append(field_name)
+                return Mutable.coerce(key, value)
+            except ValueError as e:
+                raise exceptions.StorageError('SQL Storage error: {0}'.format(str(e)))
+        else:
+            return value
+
+    def __setitem__(self, key, value):
+        list.__setitem__(self, key, value)
+        self.changed()
+
+    def __delitem__(self, key):
+        list.__delitem__(self, key)
+
 
-        unexpected_fields = input_fields.keys()
-        return missing, unexpected_fields
+Dict = _MutableDict.as_mutable(_DictType)
+List = _MutableList.as_mutable(_ListType)
 
 
-class Storage(LoggerMixin):
+class SQLModelBase(Model):
     """
-    Represents the storage
+    Abstract base class for all SQL models that allows [de]serialization
     """
-    def __init__(self, driver, items=(), **kwargs):
-        super(Storage, self).__init__(**kwargs)
-        self.driver = driver
-        self.registered = {}
-        for item in items:
-            self.register(item)
-        self.logger.debug('{name} object is ready: {0!r}'.format(
-            self, name=self.__class__.__name__))
+    # SQLAlchemy syntax
+    __abstract__ = True
 
-    def __repr__(self):
-        return '{name}(driver={self.driver})'.format(
-            name=self.__class__.__name__, self=self)
+    # This would be overridden once the models are created. Created for pylint.
+    __table__ = None
+
+    _private_fields = []
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
 
-    def __getattr__(self, item):
-        try:
-            return self.registered[item]
-        except KeyError:
-            return super(Storage, self).__getattribute__(item)
+    def to_dict(self, suppress_error=False):
+        """Return a dict representation of the model
 
-    def setup(self):
+        :param suppress_error: If set to True, sets `None` to attributes that
+        it's unable to retrieve (e.g., if a relationship wasn't established
+        yet, and so it's impossible to access a property through it)
         """
-        Setup and create all storage items
+        if suppress_error:
+            res = dict()
+            for field in self.fields():
+                try:
+                    field_value = getattr(self, field)
+                except AttributeError:
+                    field_value = None
+                res[field] = field_value
+        else:
+            # Can't simply call here `self.to_response()` because inheriting
+            # class might override it, but we always need the same code here
+            res = dict((f, getattr(self, f)) for f in self.fields())
+        return res
+
+    @classmethod
+    def fields(cls):
+        """Return the list of field names for this table
+
+        Mostly for backwards compatibility in the code (that uses `fields`)
         """
-        for name, api in self.registered.iteritems():
-            try:
-                api.create()
-                self.logger.debug(
-                    'setup {name} in storage {self!r}'.format(name=name, self=self))
-            except StorageError:
-                pass
+        return set(cls.__table__.columns.keys()) - set(cls._private_fields)
+
+    def __repr__(self):
+        return '<{0} id=`{1}`>'.format(self.__class__.__name__, self.id)

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/aria/utils/application.py
----------------------------------------------------------------------
diff --git a/aria/utils/application.py b/aria/utils/application.py
index b1a7fcc..113e054 100644
--- a/aria/utils/application.py
+++ b/aria/utils/application.py
@@ -117,7 +117,7 @@ class StorageManager(LoggerMixin):
             updated_at=now,
             main_file_name=main_file_name,
         )
-        self.model_storage.blueprint.store(blueprint)
+        self.model_storage.blueprint.put(blueprint)
         self.logger.debug('created blueprint model storage entry')
 
     def create_nodes_storage(self):
@@ -138,7 +138,7 @@ class StorageManager(LoggerMixin):
             scalable = node_copy.pop('capabilities')['scalable']['properties']
             for index, relationship in enumerate(node_copy['relationships']):
                 relationship = self.model_storage.relationship.model_cls(**relationship)
-                self.model_storage.relationship.store(relationship)
+                self.model_storage.relationship.put(relationship)
                 node_copy['relationships'][index] = relationship
 
             node_copy = self.model_storage.node.model_cls(
@@ -149,7 +149,7 @@ class StorageManager(LoggerMixin):
                 max_number_of_instances=scalable['max_instances'],
                 number_of_instances=scalable['current_instances'],
                 **node_copy)
-            self.model_storage.node.store(node_copy)
+            self.model_storage.node.put(node_copy)
 
     def create_deployment_storage(self):
         """
@@ -190,7 +190,7 @@ class StorageManager(LoggerMixin):
             created_at=now,
             updated_at=now
         )
-        self.model_storage.deployment.store(deployment)
+        self.model_storage.deployment.put(deployment)
         self.logger.debug('created deployment model storage entry')
 
     def create_node_instances_storage(self):
@@ -213,7 +213,7 @@ class StorageManager(LoggerMixin):
                     type=relationship_instance['type'],
                     target_id=relationship_instance['target_id'])
                 relationship_instances.append(relationship_instance_model)
-                self.model_storage.relationship_instance.store(relationship_instance_model)
+                self.model_storage.relationship_instance.put(relationship_instance_model)
 
             node_instance_model = self.model_storage.node_instance.model_cls(
                 node=node_model,
@@ -224,7 +224,7 @@ class StorageManager(LoggerMixin):
                 version='1.0',
                 relationship_instances=relationship_instances)
 
-            self.model_storage.node_instance.store(node_instance_model)
+            self.model_storage.node_instance.put(node_instance_model)
         self.logger.debug('created node-instances model storage entries')
 
     def create_plugin_storage(self, plugin_id, source):
@@ -258,7 +258,7 @@ class StorageManager(LoggerMixin):
             supported_py_versions=plugin.get('supported_python_versions'),
             uploaded_at=now
         )
-        self.model_storage.plugin.store(plugin)
+        self.model_storage.plugin.put(plugin)
         self.logger.debug('created plugin model storage entry')
 
 

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/requirements.txt
----------------------------------------------------------------------
diff --git a/requirements.txt b/requirements.txt
index e6d5393..7e87c67 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -23,3 +23,4 @@ Jinja2==2.8
 shortuuid==0.4.3
 CacheControl[filecache]==0.11.6
 clint==0.5.1
+SQLAlchemy==1.1.4
\ No newline at end of file

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/tests/mock/context.py
----------------------------------------------------------------------
diff --git a/tests/mock/context.py b/tests/mock/context.py
index 5fda07e..1904140 100644
--- a/tests/mock/context.py
+++ b/tests/mock/context.py
@@ -15,23 +15,53 @@
 
 from aria import application_model_storage
 from aria.orchestrator import context
+from aria.storage.sql_mapi import SQLAlchemyModelAPI
 
 from . import models
-from ..storage import InMemoryModelDriver
 
 
-def simple(**kwargs):
-    storage = application_model_storage(InMemoryModelDriver())
-    storage.setup()
-    storage.blueprint.store(models.get_blueprint())
-    storage.deployment.store(models.get_deployment())
+def simple(api_kwargs, **kwargs):
+    model_storage = application_model_storage(SQLAlchemyModelAPI, api_kwargs=api_kwargs)
+    blueprint = models.get_blueprint()
+    model_storage.blueprint.put(blueprint)
+    deployment = models.get_deployment(blueprint)
+    model_storage.deployment.put(deployment)
+
+    #################################################################################
+    # Creating a simple deployment with node -> node as a graph
+
+    dependency_node = models.get_dependency_node(deployment)
+    model_storage.node.put(dependency_node)
+    storage_dependency_node = model_storage.node.get(dependency_node.id)
+
+    dependency_node_instance = models.get_dependency_node_instance(storage_dependency_node)
+    model_storage.node_instance.put(dependency_node_instance)
+    storage_dependency_node_instance = model_storage.node_instance.get(dependency_node_instance.id)
+
+    dependent_node = models.get_dependent_node(deployment)
+    model_storage.node.put(dependent_node)
+    storage_dependent_node = model_storage.node.get(dependent_node.id)
+
+    dependent_node_instance = models.get_dependent_node_instance(storage_dependent_node)
+    model_storage.node_instance.put(dependent_node_instance)
+    storage_dependent_node_instance = model_storage.node_instance.get(dependent_node_instance.id)
+
+    relationship = models.get_relationship(storage_dependent_node, storage_dependency_node)
+    model_storage.relationship.put(relationship)
+    storage_relationship = model_storage.relationship.get(relationship.id)
+    relationship_instance = models.get_relationship_instance(
+        relationship=storage_relationship,
+        target_instance=storage_dependency_node_instance,
+        source_instance=storage_dependent_node_instance
+    )
+    model_storage.relationship_instance.put(relationship_instance)
+
     final_kwargs = dict(
         name='simple_context',
-        model_storage=storage,
+        model_storage=model_storage,
         resource_storage=None,
-        deployment_id=models.DEPLOYMENT_ID,
-        workflow_id=models.WORKFLOW_ID,
-        execution_id=models.EXECUTION_ID,
+        deployment_id=deployment.id,
+        workflow_name=models.WORKFLOW_NAME,
         task_max_attempts=models.TASK_MAX_ATTEMPTS,
         task_retry_interval=models.TASK_RETRY_INTERVAL
     )

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/tests/mock/models.py
----------------------------------------------------------------------
diff --git a/tests/mock/models.py b/tests/mock/models.py
index 327b0b9..e2e3d2f 100644
--- a/tests/mock/models.py
+++ b/tests/mock/models.py
@@ -19,24 +19,24 @@ from aria.storage import models
 
 from . import operations
 
-DEPLOYMENT_ID = 'test_deployment_id'
-BLUEPRINT_ID = 'test_blueprint_id'
-WORKFLOW_ID = 'test_workflow_id'
-EXECUTION_ID = 'test_execution_id'
+DEPLOYMENT_NAME = 'test_deployment_id'
+BLUEPRINT_NAME = 'test_blueprint_id'
+WORKFLOW_NAME = 'test_workflow_id'
+EXECUTION_NAME = 'test_execution_id'
 TASK_RETRY_INTERVAL = 1
 TASK_MAX_ATTEMPTS = 1
 
-DEPENDENCY_NODE_ID = 'dependency_node'
-DEPENDENCY_NODE_INSTANCE_ID = 'dependency_node_instance'
-DEPENDENT_NODE_ID = 'dependent_node'
-DEPENDENT_NODE_INSTANCE_ID = 'dependent_node_instance'
+DEPENDENCY_NODE_NAME = 'dependency_node'
+DEPENDENCY_NODE_INSTANCE_NAME = 'dependency_node_instance'
+DEPENDENT_NODE_NAME = 'dependent_node'
+DEPENDENT_NODE_INSTANCE_NAME = 'dependent_node_instance'
+RELATIONSHIP_NAME = 'relationship'
+RELATIONSHIP_INSTANCE_NAME = 'relationship_instance'
 
 
-def get_dependency_node():
+def get_dependency_node(deployment):
     return models.Node(
-        id=DEPENDENCY_NODE_ID,
-        host_id=DEPENDENCY_NODE_ID,
-        blueprint_id=BLUEPRINT_ID,
+        name=DEPENDENCY_NODE_NAME,
         type='test_node_type',
         type_hierarchy=[],
         number_of_instances=1,
@@ -44,28 +44,28 @@ def get_dependency_node():
         deploy_number_of_instances=1,
         properties={},
         operations=dict((key, {}) for key in operations.NODE_OPERATIONS),
-        relationships=[],
         min_number_of_instances=1,
         max_number_of_instances=1,
+        deployment_id=deployment.id
     )
 
 
-def get_dependency_node_instance(dependency_node=None):
+def get_dependency_node_instance(dependency_node):
     return models.NodeInstance(
-        id=DEPENDENCY_NODE_INSTANCE_ID,
-        host_id=DEPENDENCY_NODE_INSTANCE_ID,
-        deployment_id=DEPLOYMENT_ID,
+        name=DEPENDENCY_NODE_INSTANCE_NAME,
         runtime_properties={'ip': '1.1.1.1'},
         version=None,
-        relationship_instances=[],
-        node=dependency_node or get_dependency_node()
+        node_id=dependency_node.id,
+        deployment_id=dependency_node.deployment.id,
+        state='',
+        scaling_groups={}
     )
 
 
 def get_relationship(source=None, target=None):
     return models.Relationship(
-        source_id=source.id if source is not None else DEPENDENT_NODE_ID,
-        target_id=target.id if target is not None else DEPENDENCY_NODE_ID,
+        source_node_id=source.id,
+        target_node_id=target.id,
         source_interfaces={},
         source_operations=dict((key, {}) for key in operations.RELATIONSHIP_OPERATIONS),
         target_interfaces={},
@@ -76,23 +76,18 @@ def get_relationship(source=None, target=None):
     )
 
 
-def get_relationship_instance(source_instance=None, target_instance=None, relationship=None):
+def get_relationship_instance(source_instance, target_instance, relationship):
     return models.RelationshipInstance(
-        target_id=target_instance.id if target_instance else DEPENDENCY_NODE_INSTANCE_ID,
-        target_name='test_target_name',
-        source_id=source_instance.id if source_instance else DEPENDENT_NODE_INSTANCE_ID,
-        source_name='test_source_name',
-        type='some_type',
-        relationship=relationship or get_relationship(target_instance.node
-                                                      if target_instance else None)
+        relationship_id=relationship.id,
+        target_node_instance_id=target_instance.id,
+        source_node_instance_id=source_instance.id,
     )
 
 
-def get_dependent_node(relationship=None):
+def get_dependent_node(deployment):
     return models.Node(
-        id=DEPENDENT_NODE_ID,
-        host_id=DEPENDENT_NODE_ID,
-        blueprint_id=BLUEPRINT_ID,
+        name=DEPENDENT_NODE_NAME,
+        deployment_id=deployment.id,
         type='test_node_type',
         type_hierarchy=[],
         number_of_instances=1,
@@ -100,21 +95,20 @@ def get_dependent_node(relationship=None):
         deploy_number_of_instances=1,
         properties={},
         operations=dict((key, {}) for key in operations.NODE_OPERATIONS),
-        relationships=[relationship or get_relationship()],
         min_number_of_instances=1,
         max_number_of_instances=1,
     )
 
 
-def get_dependent_node_instance(relationship_instance=None, dependent_node=None):
+def get_dependent_node_instance(dependent_node):
     return models.NodeInstance(
-        id=DEPENDENT_NODE_INSTANCE_ID,
-        host_id=DEPENDENT_NODE_INSTANCE_ID,
-        deployment_id=DEPLOYMENT_ID,
+        name=DEPENDENT_NODE_INSTANCE_NAME,
         runtime_properties={},
         version=None,
-        relationship_instances=[relationship_instance or get_relationship_instance()],
-        node=dependent_node or get_dependency_node()
+        node_id=dependent_node.id,
+        deployment_id=dependent_node.deployment.id,
+        state='',
+        scaling_groups={}
     )
 
 
@@ -122,7 +116,7 @@ def get_blueprint():
     now = datetime.now()
     return models.Blueprint(
         plan={},
-        id=BLUEPRINT_ID,
+        name=BLUEPRINT_NAME,
         description=None,
         created_at=now,
         updated_at=now,
@@ -130,25 +124,31 @@ def get_blueprint():
     )
 
 
-def get_execution():
+def get_execution(deployment):
     return models.Execution(
-        id=EXECUTION_ID,
+        deployment_id=deployment.id,
+        blueprint_id=deployment.blueprint.id,
         status=models.Execution.STARTED,
-        deployment_id=DEPLOYMENT_ID,
-        workflow_id=WORKFLOW_ID,
-        blueprint_id=BLUEPRINT_ID,
+        workflow_name=WORKFLOW_NAME,
         started_at=datetime.utcnow(),
         parameters=None
     )
 
 
-def get_deployment():
+def get_deployment(blueprint):
     now = datetime.utcnow()
     return models.Deployment(
-        id=DEPLOYMENT_ID,
-        description=None,
+        name=DEPLOYMENT_NAME,
+        blueprint_id=blueprint.id,
+        description='',
         created_at=now,
         updated_at=now,
-        blueprint_id=BLUEPRINT_ID,
-        workflows={}
+        workflows={},
+        inputs={},
+        groups={},
+        permalink='',
+        policy_triggers={},
+        policy_types={},
+        outputs={},
+        scaling_groups={},
     )

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/tests/orchestrator/context/test_operation.py
----------------------------------------------------------------------
diff --git a/tests/orchestrator/context/test_operation.py b/tests/orchestrator/context/test_operation.py
index 6b3e28d..b5f52a3 100644
--- a/tests/orchestrator/context/test_operation.py
+++ b/tests/orchestrator/context/test_operation.py
@@ -23,7 +23,7 @@ from aria.orchestrator import context
 from aria.orchestrator.workflows import api
 from aria.orchestrator.workflows.executor import thread
 
-from tests import mock
+from tests import mock, storage
 from . import (
     op_path,
     op_name,
@@ -34,8 +34,10 @@ global_test_holder = {}
 
 
 @pytest.fixture
-def ctx():
-    return mock.context.simple()
+def ctx(tmpdir):
+    context = mock.context.simple(storage.get_sqlite_api_kwargs(str(tmpdir)))
+    yield context
+    storage.release_sqlite_storage(context.model)
 
 
 @pytest.fixture
@@ -50,14 +52,13 @@ def executor():
 def test_node_operation_task_execution(ctx, executor):
     operation_name = 'aria.interfaces.lifecycle.create'
 
-    node = mock.models.get_dependency_node()
+    node = ctx.model.node.get_by_name(mock.models.DEPENDENCY_NODE_NAME)
     node.operations[operation_name] = {
         'operation': op_path(my_operation, module_path=__name__)
 
     }
-    node_instance = mock.models.get_dependency_node_instance(node)
-    ctx.model.node.store(node)
-    ctx.model.node_instance.store(node_instance)
+    ctx.model.node.update(node)
+    node_instance = ctx.model.node_instance.get_by_name(mock.models.DEPENDENCY_NODE_INSTANCE_NAME)
 
     inputs = {'putput': True}
 
@@ -90,26 +91,19 @@ def test_node_operation_task_execution(ctx, executor):
 
 def test_relationship_operation_task_execution(ctx, executor):
     operation_name = 'aria.interfaces.relationship_lifecycle.postconfigure'
-
-    dependency_node = mock.models.get_dependency_node()
-    dependency_node_instance = mock.models.get_dependency_node_instance()
-    relationship = mock.models.get_relationship(target=dependency_node)
+    relationship = ctx.model.relationship.list()[0]
     relationship.source_operations[operation_name] = {
         'operation': op_path(my_operation, module_path=__name__)
     }
-    relationship_instance = mock.models.get_relationship_instance(
-        target_instance=dependency_node_instance,
-        relationship=relationship)
-    dependent_node = mock.models.get_dependent_node()
-    dependent_node_instance = mock.models.get_dependent_node_instance(
-        relationship_instance=relationship_instance,
-        dependent_node=dependency_node)
-    ctx.model.node.store(dependency_node)
-    ctx.model.node_instance.store(dependency_node_instance)
-    ctx.model.relationship.store(relationship)
-    ctx.model.relationship_instance.store(relationship_instance)
-    ctx.model.node.store(dependent_node)
-    ctx.model.node_instance.store(dependent_node_instance)
+    ctx.model.relationship.update(relationship)
+    relationship_instance = ctx.model.relationship_instance.list()[0]
+
+    dependency_node = ctx.model.node.get_by_name(mock.models.DEPENDENCY_NODE_NAME)
+    dependency_node_instance = \
+        ctx.model.node_instance.get_by_name(mock.models.DEPENDENCY_NODE_INSTANCE_NAME)
+    dependent_node = ctx.model.node.get_by_name(mock.models.DEPENDENT_NODE_NAME)
+    dependent_node_instance = \
+        ctx.model.node_instance.get_by_name(mock.models.DEPENDENT_NODE_INSTANCE_NAME)
 
     inputs = {'putput': True}
 
@@ -146,11 +140,49 @@ def test_relationship_operation_task_execution(ctx, executor):
     assert operation_context.source_node_instance == dependent_node_instance
 
 
+def test_invalid_task_operation_id(ctx, executor):
+    """
+    Checks that the right id is used. The task created with id == 1, thus running the task on
+    node_instance with id == 2. will check that indeed the node_instance uses the correct id.
+    :param ctx:
+    :param executor:
+    :return:
+    """
+    operation_name = 'aria.interfaces.lifecycle.create'
+    other_node_instance, node_instance = ctx.model.node_instance.list()
+    assert other_node_instance.id == 1
+    assert node_instance.id == 2
+
+    node = node_instance.node
+    node.operations[operation_name] = {
+        'operation': op_path(get_node_instance_id, module_path=__name__)
+
+    }
+    ctx.model.node.update(node)
+
+    @workflow
+    def basic_workflow(graph, **_):
+        graph.add_tasks(
+            api.task.OperationTask.node_instance(name=operation_name, instance=node_instance)
+        )
+
+    execute(workflow_func=basic_workflow, workflow_context=ctx, executor=executor)
+
+    op_node_instance_id = global_test_holder[op_name(node_instance, operation_name)]
+    assert op_node_instance_id == node_instance.id
+    assert op_node_instance_id != other_node_instance.id
+
+
 @operation
 def my_operation(ctx, **_):
     global_test_holder[ctx.name] = ctx
 
 
+@operation
+def get_node_instance_id(ctx, **_):
+    global_test_holder[ctx.name] = ctx.node_instance.id
+
+
 @pytest.fixture(autouse=True)
 def cleanup():
     global_test_holder.clear()

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/tests/orchestrator/context/test_toolbelt.py
----------------------------------------------------------------------
diff --git a/tests/orchestrator/context/test_toolbelt.py b/tests/orchestrator/context/test_toolbelt.py
index 547e62b..da46696 100644
--- a/tests/orchestrator/context/test_toolbelt.py
+++ b/tests/orchestrator/context/test_toolbelt.py
@@ -21,7 +21,7 @@ from aria.orchestrator.workflows import api
 from aria.orchestrator.workflows.executor import thread
 from aria.orchestrator.context.toolbelt import RelationshipToolBelt
 
-from tests import mock
+from tests import mock, storage
 from . import (
     op_path,
     op_name,
@@ -32,8 +32,10 @@ global_test_holder = {}
 
 
 @pytest.fixture
-def workflow_context():
-    return mock.context.simple()
+def workflow_context(tmpdir):
+    context = mock.context.simple(storage.get_sqlite_api_kwargs(str(tmpdir)))
+    yield context
+    storage.release_sqlite_storage(context.model)
 
 
 @pytest.fixture
@@ -45,63 +47,39 @@ def executor():
         result.close()
 
 
-def _create_simple_model_in_storage(workflow_context):
-    dependency_node = mock.models.get_dependency_node()
-    dependency_node_instance = mock.models.get_dependency_node_instance(
-        dependency_node=dependency_node)
-    relationship = mock.models.get_relationship(target=dependency_node)
-    relationship_instance = mock.models.get_relationship_instance(
-        target_instance=dependency_node_instance, relationship=relationship)
-    dependent_node = mock.models.get_dependent_node()
-    dependent_node_instance = mock.models.get_dependent_node_instance(
-        relationship_instance=relationship_instance, dependent_node=dependency_node)
-    workflow_context.model.node.store(dependency_node)
-    workflow_context.model.node_instance.store(dependency_node_instance)
-    workflow_context.model.relationship.store(relationship)
-    workflow_context.model.relationship_instance.store(relationship_instance)
-    workflow_context.model.node.store(dependent_node)
-    workflow_context.model.node_instance.store(dependent_node_instance)
-    return dependency_node, dependency_node_instance, \
-           dependent_node, dependent_node_instance, \
-           relationship, relationship_instance
+def _get_elements(workflow_context):
+    dependency_node = workflow_context.model.node.get_by_name(mock.models.DEPENDENCY_NODE_NAME)
+    dependency_node.host_id = dependency_node.id
+    workflow_context.model.node.update(dependency_node)
 
+    dependency_node_instance = workflow_context.model.node_instance.get_by_name(
+        mock.models.DEPENDENCY_NODE_INSTANCE_NAME)
+    dependency_node_instance.host_id = dependency_node_instance.id
+    workflow_context.model.node_instance.update(dependency_node_instance)
 
-def test_host_ip(workflow_context, executor):
-    operation_name = 'aria.interfaces.lifecycle.create'
-    dependency_node, dependency_node_instance, _, _, _, _ = \
-        _create_simple_model_in_storage(workflow_context)
-    dependency_node.operations[operation_name] = {
-        'operation': op_path(host_ip, module_path=__name__)
-
-    }
-    workflow_context.model.node.store(dependency_node)
-    inputs = {'putput': True}
-
-    @workflow
-    def basic_workflow(graph, **_):
-        graph.add_tasks(
-            api.task.OperationTask.node_instance(
-                instance=dependency_node_instance,
-                name=operation_name,
-                inputs=inputs
-            )
-        )
+    dependent_node = workflow_context.model.node.get_by_name(mock.models.DEPENDENT_NODE_NAME)
+    dependent_node.host_id = dependency_node.id
+    workflow_context.model.node.update(dependent_node)
 
-    execute(workflow_func=basic_workflow, workflow_context=workflow_context, executor=executor)
+    dependent_node_instance = workflow_context.model.node_instance.get_by_name(
+        mock.models.DEPENDENT_NODE_INSTANCE_NAME)
+    dependent_node_instance.host_id = dependent_node_instance.id
+    workflow_context.model.node_instance.update(dependent_node_instance)
 
-    assert global_test_holder.get('host_ip') == \
-           dependency_node_instance.runtime_properties.get('ip')
+    relationship = workflow_context.model.relationship.list()[0]
+    relationship_instance = workflow_context.model.relationship_instance.list()[0]
+    return dependency_node, dependency_node_instance, dependent_node, dependent_node_instance, \
+        relationship, relationship_instance
 
 
-def test_dependent_node_instances(workflow_context, executor):
+def test_host_ip(workflow_context, executor):
     operation_name = 'aria.interfaces.lifecycle.create'
-    dependency_node, dependency_node_instance, _, dependent_node_instance, _, _ = \
-        _create_simple_model_in_storage(workflow_context)
+    dependency_node, dependency_node_instance, _, _, _, _ = _get_elements(workflow_context)
     dependency_node.operations[operation_name] = {
-        'operation': op_path(dependent_nodes, module_path=__name__)
+        'operation': op_path(host_ip, module_path=__name__)
 
     }
-    workflow_context.model.node.store(dependency_node)
+    workflow_context.model.node.put(dependency_node)
     inputs = {'putput': True}
 
     @workflow
@@ -116,18 +94,18 @@ def test_dependent_node_instances(workflow_context, executor):
 
     execute(workflow_func=basic_workflow, workflow_context=workflow_context, executor=executor)
 
-    assert list(global_test_holder.get('dependent_node_instances', [])) == \
-           list([dependent_node_instance])
+    assert global_test_holder.get('host_ip') == \
+           dependency_node_instance.runtime_properties.get('ip')
 
 
 def test_relationship_tool_belt(workflow_context, executor):
     operation_name = 'aria.interfaces.relationship_lifecycle.postconfigure'
     _, _, _, _, relationship, relationship_instance = \
-        _create_simple_model_in_storage(workflow_context)
+        _get_elements(workflow_context)
     relationship.source_operations[operation_name] = {
         'operation': op_path(relationship_operation, module_path=__name__)
     }
-    workflow_context.model.relationship.store(relationship)
+    workflow_context.model.relationship.put(relationship)
 
     inputs = {'putput': True}
 
@@ -152,17 +130,13 @@ def test_wrong_model_toolbelt():
     with pytest.raises(RuntimeError):
         context.toolbelt(None)
 
+
 @operation(toolbelt=True)
 def host_ip(toolbelt, **_):
     global_test_holder['host_ip'] = toolbelt.host_ip
 
 
 @operation(toolbelt=True)
-def dependent_nodes(toolbelt, **_):
-    global_test_holder['dependent_node_instances'] = list(toolbelt.dependent_node_instances)
-
-
-@operation(toolbelt=True)
 def relationship_operation(ctx, toolbelt, **_):
     global_test_holder[ctx.name] = toolbelt
 

http://git-wip-us.apache.org/repos/asf/incubator-ariatosca/blob/c6c92ae5/tests/orchestrator/context/test_workflow.py
----------------------------------------------------------------------
diff --git a/tests/orchestrator/context/test_workflow.py b/tests/orchestrator/context/test_workflow.py
index 258f0c5..496c1ff 100644
--- a/tests/orchestrator/context/test_workflow.py
+++ b/tests/orchestrator/context/test_workflow.py
@@ -19,20 +19,19 @@ import pytest
 
 from aria import application_model_storage
 from aria.orchestrator import context
-
+from aria.storage.sql_mapi import SQLAlchemyModelAPI
+from tests import storage as test_storage
 from tests.mock import models
-from tests.storage import InMemoryModelDriver
 
 
 class TestWorkflowContext(object):
 
     def test_execution_creation_on_workflow_context_creation(self, storage):
-        self._create_ctx(storage)
-        execution = storage.execution.get(models.EXECUTION_ID)
-        assert execution.id == models.EXECUTION_ID
-        assert execution.deployment_id == models.DEPLOYMENT_ID
-        assert execution.workflow_id == models.WORKFLOW_ID
-        assert execution.blueprint_id == models.BLUEPRINT_ID
+        ctx = self._create_ctx(storage)
+        execution = storage.execution.get(ctx.execution.id)             # pylint: disable=no-member
+        assert execution.deployment == storage.deployment.get_by_name(models.DEPLOYMENT_NAME)
+        assert execution.workflow_name == models.WORKFLOW_NAME
+        assert execution.blueprint == storage.blueprint.get_by_name(models.BLUEPRINT_NAME)
         assert execution.status == storage.execution.model_cls.PENDING
         assert execution.parameters == {}
         assert execution.created_at <= datetime.utcnow()
@@ -43,13 +42,17 @@ class TestWorkflowContext(object):
 
     @staticmethod
     def _create_ctx(storage):
+        """
+
+        :param storage:
+        :return WorkflowContext:
+        """
         return context.workflow.WorkflowContext(
             name='simple_context',
             model_storage=storage,
             resource_storage=None,
-            deployment_id=models.DEPLOYMENT_ID,
-            workflow_id=models.WORKFLOW_ID,
-            execution_id=models.EXECUTION_ID,
+            deployment_id=storage.deployment.get_by_name(models.DEPLOYMENT_NAME).id,
+            workflow_name=models.WORKFLOW_NAME,
             task_max_attempts=models.TASK_MAX_ATTEMPTS,
             task_retry_interval=models.TASK_RETRY_INTERVAL
         )
@@ -57,8 +60,10 @@ class TestWorkflowContext(object):
 
 @pytest.fixture(scope='function')
 def storage():
-    result = application_model_storage(InMemoryModelDriver())
-    result.setup()
-    result.blueprint.store(models.get_blueprint())
-    result.deployment.store(models.get_deployment())
-    return result
+    api_kwargs = test_storage.get_sqlite_api_kwargs()
+    workflow_storage = application_model_storage(SQLAlchemyModelAPI, api_kwargs=api_kwargs)
+    workflow_storage.blueprint.put(models.get_blueprint())
+    blueprint = workflow_storage.blueprint.get_by_name(models.BLUEPRINT_NAME)
+    workflow_storage.deployment.put(models.get_deployment(blueprint))
+    yield workflow_storage
+    test_storage.release_sqlite_storage(workflow_storage)