cr-connect-workflow/crc/services/workflow_processor.py

356 lines
16 KiB
Python

import json
import re
import xml.etree.ElementTree as ElementTree
from SpiffWorkflow import Task as SpiffTask, Workflow
from SpiffWorkflow.bpmn.BpmnScriptEngine import BpmnScriptEngine
from SpiffWorkflow.bpmn.parser.ValidationException import ValidationException
from SpiffWorkflow.bpmn.serializer.BpmnSerializer import BpmnSerializer
from SpiffWorkflow.bpmn.specs.EndEvent import EndEvent
from SpiffWorkflow.bpmn.workflow import BpmnWorkflow
from SpiffWorkflow.camunda.parser.CamundaParser import CamundaParser
from SpiffWorkflow.dmn.parser.BpmnDmnParser import BpmnDmnParser
from SpiffWorkflow.operators import Operator
from crc import session, db
from crc.api.common import ApiError
from crc.models.file import FileDataModel, FileModel, FileType
from crc.models.workflow import WorkflowStatus, WorkflowModel
from crc.scripts.script import Script
class CustomBpmnScriptEngine(BpmnScriptEngine):
"""This is a custom script processor that can be easily injected into Spiff Workflow.
Rather than execute arbitrary code, this assumes the script references a fully qualified python class
such as myapp.RandomFact. """
def execute(self, task:SpiffTask, script, **kwargs):
"""
Assume that the script read in from the BPMN file is a fully qualified python class. Instantiate
that class, pass in any data available to the current task so that it might act on it.
Assume that the class implements the "do_task" method.
This allows us to reference custom code from the BPMN diagram.
"""
commands = script.split(" ")
path_and_command = commands[0].rsplit(".", 1)
if len(path_and_command) == 1:
module_name = "crc.scripts." + self.camel_to_snake(path_and_command[0])
class_name = path_and_command[0]
else:
module_name = "crc.scripts." + path_and_command[0] + "." + self.camel_to_snake(path_and_command[1])
class_name = path_and_command[1]
try:
mod = __import__(module_name, fromlist=[class_name])
klass = getattr(mod, class_name)
study_id = task.workflow.data[WorkflowProcessor.STUDY_ID_KEY]
if not isinstance(klass(), Script):
raise ApiError("invalid_script",
"This is an internal error. The script '%s:%s' you called "
"does not properly implement the CRC Script class." %
(module_name, class_name))
klass().do_task(task, study_id, *commands[1:])
except ModuleNotFoundError as mnfe:
raise ApiError("invalid_script",
"Unable to locate Script: '%s:%s'" % (module_name, class_name), 400)
@staticmethod
def camel_to_snake(camel):
camel = camel.strip()
return re.sub(r'(?<!^)(?=[A-Z])', '_', camel).lower()
def evaluate(self, task, expression):
"""
Evaluate the given expression, within the context of the given task and
return the result.
"""
if isinstance(expression, Operator):
return expression._matches(task)
else:
return self._eval(task, expression, **task.data)
def _eval(self, task, expression, **kwargs):
locals().update(kwargs)
try :
return eval(expression)
except NameError as ne:
raise ApiError('invalid_expression',
'The expression you provided does not exist:' + expression)
class MyCustomParser(BpmnDmnParser):
"""
A BPMN and DMN parser that can also parse Camunda forms.
"""
OVERRIDE_PARSER_CLASSES = BpmnDmnParser.OVERRIDE_PARSER_CLASSES
OVERRIDE_PARSER_CLASSES.update(CamundaParser.OVERRIDE_PARSER_CLASSES)
class WorkflowProcessor(object):
_script_engine = CustomBpmnScriptEngine()
_serializer = BpmnSerializer()
WORKFLOW_ID_KEY = "workflow_id"
STUDY_ID_KEY = "study_id"
def __init__(self, workflow_model: WorkflowModel, soft_reset=False, hard_reset=False):
"""Create a Workflow Processor based on the serialized information available in the workflow model.
If soft_reset is set to true, it will try to use the latest version of the workflow specification.
If hard_reset is set to true, it will create a new Workflow, but embed the data from the last
completed task in the previous workflow.
If neither flag is set, it will use the same version of the specification that was used to originally
create the workflow model. """
orig_version = workflow_model.spec_version
if soft_reset:
spec = self.get_spec(workflow_model.workflow_spec_id)
workflow_model.spec_version = spec.description
else:
spec = self.get_spec(workflow_model.workflow_spec_id, workflow_model.spec_version)
self.workflow_spec_id = workflow_model.workflow_spec_id
try:
self.bpmn_workflow = self._serializer.deserialize_workflow(workflow_model.bpmn_workflow_json, workflow_spec=spec)
except KeyError as ke:
if soft_reset:
# Undo the soft-reset.
workflow_model.spec_version = orig_version
orig_version = workflow_model.spec_version
raise ApiError(code="unexpected_workflow_structure",
message="Failed to deserialize workflow '%s' version %s, due to a mis-placed or missing task '%s'" %
(self.workflow_spec_id, workflow_model.spec_version, str(ke)) +
" This is very likely due to a soft reset where there was a structural change.")
self.bpmn_workflow.script_engine = self._script_engine
if hard_reset:
# Now that the spec is loaded, get the data and rebuild the bpmn with the new details
workflow_model.spec_version = self.hard_reset()
@staticmethod
def get_parser():
parser = MyCustomParser()
return parser
@staticmethod
def get_latest_version_string(workflow_spec_id):
"""Version is in the format v[VERSION] (FILE_ID_LIST)
For example, a single bpmn file with only one version would be
v1 (12) Where 12 is the id of the file data model that is used to create the
specification. If multiple files exist, they are added on in
dot notation to both the version number and the file list. So
a Spec that includes a BPMN, DMN, an a Word file all on the first
version would be v1.1.1 (12.45.21)"""
# this could potentially become expensive to load all the data in the data models.
# in which case we might consider using a deferred loader for the actual data, but
# trying not to pre-optimize.
file_data_models = WorkflowProcessor.__get_latest_file_models(workflow_spec_id)
major_version = 0 # The version of the primary file.
minor_version = [] # The versions of the minor files if any.
file_ids = []
for file_data in file_data_models:
file_ids.append(file_data.id)
if file_data.file_model.primary:
major_version = file_data.version
else:
minor_version.append(file_data.version)
minor_version.insert(0, major_version) # Add major version to beginning.
version = ".".join(str(x) for x in minor_version)
files = ".".join(str(x) for x in file_ids)
full_version = "v%s (%s)" % (version, files)
return full_version
@staticmethod
def __get_file_models_for_version(workflow_spec_id, version):
file_id_strings = re.findall('\((.*)\)', version)[0].split(".")
file_ids = [int(i) for i in file_id_strings]
files = session.query(FileDataModel)\
.join(FileModel) \
.filter(FileModel.workflow_spec_id == workflow_spec_id)\
.filter(FileDataModel.id.in_(file_ids)).all()
if len(files) != len(file_ids):
raise ApiError("invalid_version",
"The version '%s' of workflow specification '%s' is invalid. Unable to locate the correct files to recreate it." %
(version, workflow_spec_id))
return files
@staticmethod
def __get_latest_file_models(workflow_spec_id):
"""Returns all the latest files related to a workflow specification"""
return session.query(FileDataModel) \
.join(FileModel) \
.filter(FileModel.workflow_spec_id == workflow_spec_id)\
.filter(FileDataModel.version == FileModel.latest_version)\
.order_by(FileModel.id)\
.all()
@staticmethod
def get_spec(workflow_spec_id, version=None):
"""Returns the requested version of the specification,
or the lastest version if none is specified."""
parser = WorkflowProcessor.get_parser()
process_id = None
if version is None:
file_data_models = WorkflowProcessor.__get_latest_file_models(workflow_spec_id)
version = WorkflowProcessor.get_latest_version_string(workflow_spec_id)
else:
file_data_models = WorkflowProcessor.__get_file_models_for_version(workflow_spec_id, version)
for file_data in file_data_models:
if file_data.file_model.type == FileType.bpmn:
bpmn: ElementTree.Element = ElementTree.fromstring(file_data.data)
if file_data.file_model.primary:
process_id = WorkflowProcessor.get_process_id(bpmn)
parser.add_bpmn_xml(bpmn, filename=file_data.file_model.name)
elif file_data.file_model.type == FileType.dmn:
dmn: ElementTree.Element = ElementTree.fromstring(file_data.data)
parser.add_dmn_xml(dmn, filename=file_data.file_model.name)
if process_id is None:
raise(ApiError(code="no_primary_bpmn_error",
message="There is no primary BPMN model defined for workflow %s" % workflow_spec_id))
try:
spec = parser.get_spec(process_id)
except ValidationException as ve:
raise ApiError(code="workflow_validation_error",
message="Failed to parse Workflow Specification '%s' %s." % (workflow_spec_id, version) +
"Error is %s" % str(ve))
spec.description = version
return spec
@staticmethod
def status_of(bpmn_workflow):
if bpmn_workflow.is_completed():
return WorkflowStatus.complete
user_tasks = bpmn_workflow.get_ready_user_tasks()
if len(user_tasks) > 0:
return WorkflowStatus.user_input_required
else:
return WorkflowStatus.waiting
@classmethod
def create(cls, study_id, workflow_spec_id):
spec = WorkflowProcessor.get_spec(workflow_spec_id)
bpmn_workflow = BpmnWorkflow(spec, script_engine=cls._script_engine)
bpmn_workflow.data[WorkflowProcessor.STUDY_ID_KEY] = study_id
bpmn_workflow.do_engine_steps()
workflow_model = WorkflowModel(status=WorkflowProcessor.status_of(bpmn_workflow),
study_id=study_id,
workflow_spec_id=workflow_spec_id,
spec_version=spec.description)
session.add(workflow_model)
session.commit()
# Need to commit twice, first to get a unique id for the workflow model, and
# a second time to store the serialization so we can maintain this link within
# the spiff-workflow process.
bpmn_workflow.data[WorkflowProcessor.WORKFLOW_ID_KEY] = workflow_model.id
workflow_model.bpmn_workflow_json = WorkflowProcessor._serializer.serialize_workflow(bpmn_workflow)
session.add(workflow_model)
session.commit()
processor = cls(workflow_model)
return processor
def hard_reset(self):
"""Recreate this workflow, but keep the data from the last completed task and add it back into the first task.
This may be useful when a workflow specification changes, and users need to review all the
prior steps, but don't need to reenter all the previous data.
Returns the new version.
"""
spec = WorkflowProcessor.get_spec(self.workflow_spec_id)
bpmn_workflow = BpmnWorkflow(spec, script_engine=self._script_engine)
bpmn_workflow.data = self.bpmn_workflow.data
for task in bpmn_workflow.get_tasks(SpiffTask.READY):
task.data = self.bpmn_workflow.last_task.data
bpmn_workflow.do_engine_steps()
self.bpmn_workflow = bpmn_workflow
return spec.description
def get_status(self):
return self.status_of(self.bpmn_workflow)
def get_spec_version(self):
"""We use the spec's descrption field to store the version information"""
return self.bpmn_workflow.spec.description
def do_engine_steps(self):
self.bpmn_workflow.do_engine_steps()
def serialize(self):
return self._serializer.serialize_workflow(self.bpmn_workflow)
def next_user_tasks(self):
return self.bpmn_workflow.get_ready_user_tasks()
def next_task(self):
"""Returns the next task that should be completed
even if there are parallel tasks and multiple options are
available.
If the workflow is complete
it will return the final end task.
"""
# If the whole blessed mess is done, return the end_event task in the tree
if self.bpmn_workflow.is_completed():
last_task = None
for task in SpiffTask.Iterator(self.bpmn_workflow.task_tree, SpiffTask.ANY_MASK):
if isinstance(task.task_spec, EndEvent):
return task
# If there are ready tasks to complete, return the next ready task, but return the one
# in the active parallel path if possible.
ready_tasks = self.bpmn_workflow.get_tasks(SpiffTask.READY)
if len(ready_tasks) > 0:
for task in ready_tasks:
if task.parent == self.bpmn_workflow.last_task:
return task
return ready_tasks[0]
# If there are no ready tasks, but the thing isn't complete yet, find the first non-complete task
# and return that
next_task = None
for task in SpiffTask.Iterator(self.bpmn_workflow.task_tree, SpiffTask.NOT_FINISHED_MASK):
next_task = task
return next_task
def complete_task(self, task):
self.bpmn_workflow.complete_task_from_id(task.id)
def get_data(self):
return self.bpmn_workflow.data
def get_workflow_id(self):
return self.bpmn_workflow.data[self.WORKFLOW_ID_KEY]
def get_study_id(self):
return self.bpmn_workflow.data[self.STUDY_ID_KEY]
def get_ready_user_tasks(self):
return self.bpmn_workflow.get_ready_user_tasks()
def get_all_user_tasks(self):
all_tasks = self.bpmn_workflow.get_tasks(SpiffTask.ANY_MASK)
return [t for t in all_tasks if not self.bpmn_workflow._is_engine_task(t.task_spec)]
@staticmethod
def get_process_id(et_root: ElementTree.Element):
process_elements = []
for child in et_root:
if child.tag.endswith('process') and child.attrib.get('isExecutable', False):
process_elements.append(child)
if len(process_elements) == 0:
raise ValidationException('No executable process tag found')
# There are multiple root elements
if len(process_elements) > 1:
# Look for the element that has the startEvent in it
for e in process_elements:
this_element: ElementTree.Element = e
for child_element in list(this_element):
if child_element.tag.endswith('startEvent'):
return this_element.attrib['id']
raise ValidationException('No start event found in %s' % et_root.attrib['id'])
return process_elements[0].attrib['id']