class Driver(object):
"""
A driver provides an API for storing and loading workflows, receiving
information regarding running Jobs, and for driving the workflow
execution.
"""
def __init__(self, db):
"""
Instantiates a new Driver.
@type db: object
@param db: An sqlalchemy database connection.
@rtype: Driver
@return: The new instance.
"""
self.db = DB(db)
self.xmlreader = XmlReader()
def install(self):
"""
Installs (or upgrades) the workflow server.
@rtype: Boolean
@return: True on success, False otherwise.
"""
return self.db.install()
def uninstall(self):
"""
Uninstall the workflow engine. This also permanently removes all data,
history, and running jobs. Use with care.
@rtype: Boolean
@return: True on success, False otherwise.
"""
return self.db.uninstall()
def get_workflow_info(self, **filter):
"""
Returns the WorkflowInfo objects that match the given criteria.
@rtype: [WorkflowInfo]
@return: A list of WorkflowInfo objects from the database.
"""
return self.db.get_workflow_info(**filter)
def save_workflow_info(self, object):
"""
Store the WorkflowInfo in the database.
@rtype: Boolean
@return: True on success, False otherwise.
"""
return self.db.save(object)
def delete_workflow_info(self, object):
"""
Delete the WorkflowInfo from the database.
@rtype: Boolean
@return: True on success, False otherwise.
"""
return self.db.delete(object)
def create_job(self, workflow_info):
"""
Creates an instance of the given workflow.
@rtype: JobInfo
@return: The JobInfo for the newly created workflow instance.
"""
if workflow_info is None:
raise WorkflowServerException('workflow_info argument is None')
if workflow_info.id is None:
raise WorkflowServerException('workflow_info must be saved first')
workflow = self.xmlreader.parse_string(workflow_info.xml)
job = Job(workflow[0])
job_info = JobInfo(workflow_info.id, job)
self.__save_job_info(job_info)
return job_info
def get_job_info(self, **filter):
"""
Returns the workflow instances that matches the given criteria.
@rtype: [JobInfo]
@return: A list of JobInfo objects from the database.
"""
return self.db.get_job_info(**filter)
def __save_job_info(self, job_info):
self.db.save(job_info)
for node in job_info.instance.task_tree:
task_info = self.get_task_info(job_id = job_info.id,
node_id = node.id)
if len(task_info) == 1:
task_info = task_info[0]
elif len(task_info) == 0:
task_info = TaskInfo(job_info.id, node)
else:
raise WorkflowServerException('More than one task found')
task_info.status = node.state
self.db.save(task_info)
def delete_job_info(self, object):
"""
Delete the workflow instance from the database.
@rtype: Boolean
@return: True on success, False otherwise.
"""
return self.db.delete(object)
def get_task_info(self, **filter):
"""
Returns the tasks that match the given criteria.
@rtype: [TaskInfo]
@return: A list of TaskInfo objects from the database.
"""
return self.db.get_task_info(**filter)
def execute_task(self, task_info):
if task_info is None:
raise WorkflowServerException('task_info argument is None')
if task_info.id is None:
raise WorkflowServerException('task_info must be saved first')
if task_info.status & task_info.WAITING == 0:
raise WorkflowServerException('task is not in WAITING state')
if task_info.job_id is None:
raise WorkflowServerException('task_info must be associated with a job')
job_info_list = self.get_job_info(id = task_info.job_id)
if len(job_info_list) == 0:
raise WorkflowServerException('Job not found')
elif len(job_info_list) > 1:
raise WorkflowServerException('Fatal error: More than one Job found')
job_info = job_info_list[0]
if job_info.status is job_info.COMPLETED:
raise WorkflowServerException('Job is already completed')
result = job_info.instance.execute_task_from_id(task_info.node_id)
self.__save_job_info(job_info)
return result
