Advanced publishing: change workflow lang schema

* 'on-success', 'on-error' and 'on-complete' can now look like
  described in "Advanced Publishing" specification [1]
* Refactored all places related to the spec changes
* Added unit tests for advanced schema of 'on-xxx' clauses

[1] https://github.com/openstack/mistral-specs/blob/master/specs/pike/approved/advanced_publishing.rst

Change-Id: I190fcec0a40ca6f97d712168f4be7a418bd1f0e8
Partially implements: blueprint mistral-advanced-publishing-global-vars
This commit is contained in:
Renat Akhmerov 2017-03-30 13:12:50 +07:00
parent a772530af2
commit 6c6e212688
11 changed files with 615 additions and 108 deletions

View File

@ -102,7 +102,8 @@ class BaseSpec(object):
It represents a DSL entity such as workflow or task as a python object
providing more convenient API to analyse DSL than just working with raw
data in form of a dictionary. Specification classes also implement
all required validation logic by overriding instance method 'validate()'.
all required validation logic by overriding instance methods
'validate_schema()' and 'validate_semantics()'.
Note that the specification mechanism allows to have polymorphic entities
in DSL. For example, if we find it more convenient to have separate
@ -197,7 +198,7 @@ class BaseSpec(object):
def validate_expr(self, dsl_part):
if isinstance(dsl_part, six.string_types):
expr.validate(dsl_part)
elif isinstance(dsl_part, list):
elif isinstance(dsl_part, (list, tuple)):
for expression in dsl_part:
if isinstance(expression, six.string_types):
expr.validate(expression)
@ -250,21 +251,6 @@ class BaseSpec(object):
elif isinstance(prop_val, six.string_types):
return {prop_val: ''}
def _as_list_of_tuples(self, prop_name):
prop_val = self._data.get(prop_name)
if not prop_val:
return []
if isinstance(prop_val, six.string_types):
return [self._as_tuple(prop_val)]
return [self._as_tuple(item) for item in prop_val]
@staticmethod
def _as_tuple(val):
return list(val.items())[0] if isinstance(val, dict) else (val, '')
@staticmethod
def _parse_cmd_and_input(cmd_str):
# TODO(rakhmerov): Try to find a way with one expression.

View File

@ -0,0 +1,87 @@
# Copyright 2014 - Mirantis, Inc.
# Copyright 2015 - StackStorm, Inc.
#
# Licensed 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.
import six
from mistral.lang import types
from mistral.lang.v2 import base
from mistral.lang.v2 import publish
class OnClauseSpec(base.BaseSpec):
_simple_schema = {
"oneOf": [
types.NONEMPTY_STRING,
types.UNIQUE_STRING_OR_EXPRESSION_CONDITION_LIST
]
}
_advanced_schema = {
"type": "object",
"properties": {
"publish": publish.PublishSpec.get_schema(includes=None),
"next": _simple_schema,
},
"additionalProperties": False
}
_schema = {"oneOf": [_simple_schema, _advanced_schema]}
def __init__(self, data):
super(OnClauseSpec, self).__init__(data)
if not isinstance(data, dict):
# Old simple schema.
self._publish = None
self._next = prepare_next_clause(data)
else:
# New advanced schema.
self._publish = self._spec_property('publish', publish.PublishSpec)
self._next = prepare_next_clause(data.get('next'))
@classmethod
def get_schema(cls, includes=['definitions']):
return super(OnClauseSpec, cls).get_schema(includes)
def get_publish(self):
return self._publish
def get_next(self):
return self._next
def _as_list_of_tuples(data):
if not data:
return []
if isinstance(data, six.string_types):
return [_as_tuple(data)]
return [_as_tuple(item) for item in data]
def _as_tuple(val):
return list(val.items())[0] if isinstance(val, dict) else (val, '')
def prepare_next_clause(next_clause):
list_of_tuples = _as_list_of_tuples(next_clause)
for i, task in enumerate(list_of_tuples):
task_name, params = OnClauseSpec._parse_cmd_and_input(task[0])
list_of_tuples[i] = (task_name, task[1], params)
return list_of_tuples

View File

@ -0,0 +1,61 @@
# Copyright 2014 - Mirantis, Inc.
# Copyright 2015 - StackStorm, Inc.
#
# Licensed 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.
from mistral import exceptions as exc
from mistral.lang import types
from mistral.lang.v2 import base
class PublishSpec(base.BaseSpec):
_schema = {
"type": "object",
"properties": {
"branch": types.NONEMPTY_DICT,
"global": types.NONEMPTY_DICT,
"atomic": types.NONEMPTY_DICT
},
"additionalProperties": False
}
def __init__(self, data):
super(PublishSpec, self).__init__(data)
self._branch = self._data.get('branch')
self._global = self._data.get('global')
self._atomic = self._data.get('atomic')
@classmethod
def get_schema(cls, includes=['definitions']):
return super(PublishSpec, cls).get_schema(includes)
def validate_semantics(self):
if not self._branch and not self._global and not self._atomic:
raise exc.InvalidModelException(
"Either 'branch', 'global' or 'atomic' must be specified: "
% self._data
)
self.validate_expr(self._branch)
self.validate_expr(self._global)
self.validate_expr(self._atomic)
def get_branch(self):
return self._branch
def get_global(self):
return self._global
def get_atomic(self):
return self._atomic

View File

@ -56,6 +56,7 @@ class RetrySpec(base.BaseSpec):
def __init__(self, data):
data = self._transform_retry_one_line(data)
super(RetrySpec, self).__init__(data)
self._break_on = data.get('break-on')

View File

@ -17,11 +17,13 @@ import six
from mistral.lang import types
from mistral.lang.v2 import base
from mistral.lang.v2 import on_clause
from mistral.lang.v2 import policies
from mistral.lang.v2 import tasks
direct_wf_ts = tasks.DirectWorkflowTaskSpec
# TODO(rakhmerov): This specification should be broken into two separate
# specs for direct and reverse workflows. It's weird to combine them into
# one because they address different use cases.
class TaskDefaultsSpec(base.BaseSpec):
@ -71,30 +73,31 @@ class TaskDefaultsSpec(base.BaseSpec):
'pause-before',
'concurrency'
)
self._on_complete = direct_wf_ts.prepare_on_clause(
self._as_list_of_tuples('on-complete')
)
self._on_success = direct_wf_ts.prepare_on_clause(
self._as_list_of_tuples('on-success')
)
self._on_error = direct_wf_ts.prepare_on_clause(
self._as_list_of_tuples('on-error')
)
on_spec_cls = on_clause.OnClauseSpec
self._on_complete = self._spec_property('on-complete', on_spec_cls)
self._on_success = self._spec_property('on-success', on_spec_cls)
self._on_error = self._spec_property('on-error', on_spec_cls)
# TODO(rakhmerov): 'requires' should reside in a different spec for
# reverse workflows.
self._requires = data.get('requires', [])
def validate_schema(self):
super(TaskDefaultsSpec, self).validate_schema()
def validate_semantics(self):
# Validate YAQL expressions.
self._validate_transitions('on-complete')
self._validate_transitions('on-success')
self._validate_transitions('on-error')
self._validate_transitions(self._on_complete)
self._validate_transitions(self._on_success)
self._validate_transitions(self._on_error)
def _validate_transitions(self, on_clause):
val = self._data.get(on_clause, [])
def _validate_transitions(self, on_clause_spec):
val = on_clause_spec.get_next() if on_clause_spec else []
if not val:
return
[self.validate_expr(t)
for t in ([val] if isinstance(val, six.string_types) else val)]
for t in ([val] if isinstance(val, six.string_types) else val)]
def get_policies(self):
return self._policies

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@ -22,8 +22,11 @@ from mistral import exceptions as exc
from mistral import expressions
from mistral.lang import types
from mistral.lang.v2 import base
from mistral.lang.v2 import on_clause
from mistral.lang.v2 import policies
from mistral.lang.v2 import publish
from mistral import utils
from mistral.workflow import states
_expr_ptrns = [expressions.patterns[name] for name in expressions.patterns]
WITH_ITEMS_PTRN = re.compile(
@ -141,8 +144,9 @@ class TaskSpec(base.BaseSpec):
for item in raw:
if not isinstance(item, six.string_types):
raise exc.InvalidModelException("'with-items' elements should"
" be strings: %s" % self._data)
raise exc.InvalidModelException(
"'with-items' elements should be strings: %s" % self._data
)
match = re.match(WITH_ITEMS_PTRN, item)
@ -209,11 +213,17 @@ class TaskSpec(base.BaseSpec):
def get_target(self):
return self._target
def get_publish(self):
return self._publish
def get_publish(self, state):
spec = None
def get_publish_on_error(self):
return self._publish_on_error
if state == states.SUCCESS and self._publish:
spec = publish.PublishSpec({'branch': self._publish})
elif state == states.ERROR and self._publish_on_error:
spec = publish.PublishSpec(
{'branch': self._publish_on_error}
)
return spec
def get_keep_result(self):
return self._keep_result
@ -222,20 +232,14 @@ class TaskSpec(base.BaseSpec):
return self._safe_rerun
def get_type(self):
if self._workflow:
return utils.WORKFLOW_TASK_TYPE
return utils.ACTION_TASK_TYPE
return (utils.WORKFLOW_TASK_TYPE if self._workflow
else utils.ACTION_TASK_TYPE)
class DirectWorkflowTaskSpec(TaskSpec):
_polymorphic_value = 'direct'
_on_clause_type = {
"oneOf": [
types.NONEMPTY_STRING,
types.UNIQUE_STRING_OR_EXPRESSION_CONDITION_LIST
]
}
_on_clause_schema = on_clause.OnClauseSpec._schema
_direct_workflow_schema = {
"type": "object",
@ -247,52 +251,62 @@ class DirectWorkflowTaskSpec(TaskSpec):
types.POSITIVE_INTEGER
]
},
"on-complete": _on_clause_type,
"on-success": _on_clause_type,
"on-error": _on_clause_type
"on-complete": _on_clause_schema,
"on-success": _on_clause_schema,
"on-error": _on_clause_schema
}
}
_schema = utils.merge_dicts(copy.deepcopy(TaskSpec._schema),
_direct_workflow_schema)
_schema = utils.merge_dicts(
copy.deepcopy(TaskSpec._schema),
_direct_workflow_schema
)
def __init__(self, data):
super(DirectWorkflowTaskSpec, self).__init__(data)
self._join = data.get('join')
self._on_complete = self.prepare_on_clause(
self._as_list_of_tuples('on-complete')
)
self._on_success = self.prepare_on_clause(
self._as_list_of_tuples('on-success')
)
self._on_error = self.prepare_on_clause(
self._as_list_of_tuples('on-error')
)
def validate_schema(self):
super(DirectWorkflowTaskSpec, self).validate_schema()
on_spec_cls = on_clause.OnClauseSpec
self._on_complete = self._spec_property('on-complete', on_spec_cls)
self._on_success = self._spec_property('on-success', on_spec_cls)
self._on_error = self._spec_property('on-error', on_spec_cls)
def validate_semantics(self):
# Validate YAQL expressions.
self._validate_transitions('on-complete')
self._validate_transitions('on-success')
self._validate_transitions('on-error')
self._validate_transitions(self._on_complete)
self._validate_transitions(self._on_success)
self._validate_transitions(self._on_error)
def _validate_transitions(self, on_clause):
val = self._data.get(on_clause, [])
def _validate_transitions(self, on_clause_spec):
val = on_clause_spec.get_next() if on_clause_spec else []
if not val:
return
[self.validate_expr(t)
for t in ([val] if isinstance(val, six.string_types) else val)]
for t in ([val] if isinstance(val, six.string_types) else val)]
@staticmethod
def prepare_on_clause(list_of_tuples):
for i, task in enumerate(list_of_tuples):
task_name, params = DirectWorkflowTaskSpec._parse_cmd_and_input(
task[0]
)
list_of_tuples[i] = (task_name, task[1], params)
def get_publish(self, state):
spec = super(DirectWorkflowTaskSpec, self).get_publish(state)
return list_of_tuples
# TODO(rakhmerov): How do we need to resolve a possible conflict
# between 'on-complete' and 'on-success/on-error' and
# 'publish/publish-on-error'? For now we assume that 'on-error'
# and 'on-success' take precedence over on-complete.
on_clause = self._on_complete
if state == states.SUCCESS:
on_clause = self._on_success
elif state == states.ERROR:
on_clause = self._on_error
if not on_clause:
return spec
return on_clause.get_publish() or spec
def get_join(self):
return self._join

View File

@ -292,42 +292,57 @@ class DirectWorkflowSpec(WorkflowSpec):
return to_task_name in t_names
def get_on_error_clause(self, t_name):
result = self.get_tasks()[t_name].get_on_error()
result = []
on_clause = self.get_tasks()[t_name].get_on_error()
if on_clause:
result = on_clause.get_next()
if not result:
t_defaults = self.get_task_defaults()
if t_defaults:
if t_defaults and t_defaults.get_on_error():
result = self._remove_task_from_clause(
t_defaults.get_on_error(),
t_defaults.get_on_error().get_next(),
t_name
)
return result
def get_on_success_clause(self, t_name):
result = self.get_tasks()[t_name].get_on_success()
result = []
on_clause = self.get_tasks()[t_name].get_on_success()
if on_clause:
result = on_clause.get_next()
if not result:
t_defaults = self.get_task_defaults()
if t_defaults:
if t_defaults and t_defaults.get_on_success():
result = self._remove_task_from_clause(
t_defaults.get_on_success(),
t_defaults.get_on_success().get_next(),
t_name
)
return result
def get_on_complete_clause(self, t_name):
result = self.get_tasks()[t_name].get_on_complete()
result = []
on_clause = self.get_tasks()[t_name].get_on_complete()
if on_clause:
result = on_clause.get_next()
if not result:
t_defaults = self.get_task_defaults()
if t_defaults:
if t_defaults and t_defaults.get_on_complete():
result = self._remove_task_from_clause(
t_defaults.get_on_complete(),
t_defaults.get_on_complete().get_next(),
t_name
)

View File

@ -713,6 +713,43 @@ class DataFlowEngineTest(engine_test_base.EngineTestCase):
self.assertDictEqual(wf_input['a'], task1.published['published_a'])
def test_advanced_publishing_branch(self):
wf_text = """---
version: 2.0
wf:
tasks:
task1:
action: std.noop
on-success:
publish:
branch:
my_var: my branch value
next: task2
task2:
action: std.echo output=<% $.my_var %>
"""
wf_service.create_workflows(wf_text)
# Start workflow.
wf_ex = self.engine.start_workflow('wf', {})
self.await_workflow_success(wf_ex.id)
with db_api.transaction():
# Note: We need to reread execution to access related tasks.
wf_ex = db_api.get_workflow_execution(wf_ex.id)
tasks = wf_ex.task_executions
task1 = self._assert_single_item(tasks, name='task1')
self._assert_single_item(tasks, name='task2')
self.assertDictEqual({"my_var": "my branch value"}, task1.published)
class DataFlowTest(test_base.BaseTest):
def test_get_task_execution_result(self):

View File

@ -334,6 +334,306 @@ class TaskSpecValidation(v2_base.WorkflowSpecValidationTestCase):
expect_error=expect_error
)
def test_direct_transition_advanced_schema(self):
tests = [
({'on-success': {'publish': {'var1': 1234}}}, True),
({'on-success': {'publish': {'branch': {'var1': 1234}}}}, False),
(
{
'on-success': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
}
}
},
False
),
(
{
'on-success': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': '<% * %>'},
'atomic': {'atomic_var1': '<% my_func() %>'}
}
}
},
True
),
(
{
'on-success': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': 'email'
}
},
False
),
(
{
'on-success': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': ['email']
}
},
False
),
(
{
'on-success': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% 1 %>'}]
}
},
False
),
(
{
'on-success': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% $.v1 and $.v2 %>'}]
}
},
False
),
(
{
'on-success': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% * %>'}]
}
},
True
),
({'on-success': {'next': [{'email': '<% $.v1 %>'}]}}, False),
({'on-success': {'next': 'email'}}, False),
({'on-success': {'next': ['email']}}, False),
({'on-success': {'next': [{'email': 'email'}]}}, True),
({'on-error': {'publish': {'var1': 1234}}}, True),
({'on-error': {'publish': {'branch': {'var1': 1234}}}}, False),
(
{
'on-error': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
}
}
},
False
),
(
{
'on-error': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': '<% * %>'},
'atomic': {'atomic_var1': '<% my_func() %>'}
}
}
},
True
),
(
{
'on-error': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': 'email'
}
},
False
),
(
{
'on-error': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': ['email']
}
},
False
),
(
{
'on-error': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% 1 %>'}]
}
},
False
),
(
{
'on-error': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% $.v1 and $.v2 %>'}]
}
},
False
),
(
{
'on-error': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% * %>'}]
}
},
True
),
({'on-error': {'next': [{'email': '<% $.v1 %>'}]}}, False),
({'on-error': {'next': 'email'}}, False),
({'on-error': {'next': ['email']}}, False),
({'on-error': {'next': [{'email': 'email'}]}}, True),
({'on-complete': {'publish': {'var1': 1234}}}, True),
({'on-complete': {'publish': {'branch': {'var1': 1234}}}}, False),
(
{
'on-complete': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
}
}
},
False
),
(
{
'on-complete': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': '<% * %>'},
'atomic': {'atomic_var1': '<% my_func() %>'}
}
}
},
True
),
(
{
'on-complete': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': 'email'
}
},
False
),
(
{
'on-complete': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': ['email']
}
},
False
),
(
{
'on-complete': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% 1 %>'}]
}
},
False
),
(
{
'on-complete': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% $.v1 and $.v2 %>'}]
}
},
False
),
(
{
'on-complete': {
'publish': {
'branch': {'var1': 1234},
'global': {'global_var1': 'val'},
'atomic': {'atomic_var1': '<% my_func() %>'}
},
'next': [{'email': '<% * %>'}]
}
},
True
),
({'on-complete': {'next': [{'email': '<% $.v1 %>'}]}}, False),
({'on-complete': {'next': 'email'}}, False),
({'on-complete': {'next': ['email']}}, False),
({'on-complete': {'next': [{'email': 'email'}]}}, True)
]
for transition, expect_error in tests:
overlay = {'test': {'tasks': {}}}
utils.merge_dicts(overlay['test']['tasks'], {'get': transition})
self._parse_dsl_spec(
add_tasks=True,
changes=overlay,
expect_error=expect_error
)
def test_join(self):
tests = [
({'join': ''}, True),

View File

@ -121,15 +121,15 @@ class WorkbookSpecValidation(base.WorkbookSpecValidationTestCase):
self.assertListEqual(
[('fail', '<% $.my_val = 0 %>', {})],
task_defaults_spec.get_on_error()
task_defaults_spec.get_on_error().get_next()
)
self.assertListEqual(
[('pause', '', {})],
task_defaults_spec.get_on_success()
task_defaults_spec.get_on_success().get_next()
)
self.assertListEqual(
[('succeed', '', {})],
task_defaults_spec.get_on_complete()
task_defaults_spec.get_on_complete().get_next()
)
task3_spec = wf2_spec.get_tasks().get('task3')
@ -150,15 +150,15 @@ class WorkbookSpecValidation(base.WorkbookSpecValidationTestCase):
)
self.assertListEqual(
[('task4', '<% $.my_val = 1 %>', {})],
task3_spec.get_on_error()
task3_spec.get_on_error().get_next()
)
self.assertListEqual(
[('task5', '<% $.my_val = 2 %>', {})],
task3_spec.get_on_success()
task3_spec.get_on_success().get_next()
)
self.assertListEqual(
[('task6', '<% $.my_val = 3 %>', {})],
task3_spec.get_on_complete()
task3_spec.get_on_complete().get_next()
)
task7_spec = wf2_spec.get_tasks().get('task7')

View File

@ -190,11 +190,7 @@ def publish_variables(task_ex, task_spec):
wf_ex = task_ex.workflow_execution
expr_ctx = ContextView(
task_ex.in_context,
wf_ex.context,
wf_ex.input
)
expr_ctx = ContextView(task_ex.in_context, wf_ex.context, wf_ex.input)
if task_ex.name in expr_ctx:
LOG.warning(
@ -202,13 +198,20 @@ def publish_variables(task_ex, task_spec):
task_ex.name
)
data = (
task_spec.get_publish()
if task_ex.state == states.SUCCESS
else task_spec.get_publish_on_error()
)
publish_spec = task_spec.get_publish(task_ex.state)
task_ex.published = expr.evaluate_recursively(data, expr_ctx)
if not publish_spec:
return
branch_vars = publish_spec.get_branch()
task_ex.published = expr.evaluate_recursively(branch_vars, expr_ctx)
# TODO(rakhmerov):
# 1. Publish global and atomic variables.
# 2. Add the field "publish" in TaskExecution model similar to "published"
# but containing info as
# {'branch': {vars}, 'global': {vars}, 'atomic': {vars}}
def evaluate_task_outbound_context(task_ex):