srned / workflowsvc

Python Workflow Service

workflowsvc

The Python Clone of Amazon Simple Workflow Service (http://aws.amazon.com/swf/).

Introduction

workflowsvc implements minimal set of the APIs supported by Simple Workflow Service. It is partly intended as a learning experience.

Dependencies

• tornado pip install tornado
• redis.py pip install redis
• mongodb pip install pymongo

API Reference

Amazon Simple Workflow Service helps coordinate work across distributed components. A task is a logical unit of work that is accomplished by a worker. A decider component arrives at decisions that determines the state of the execution and creates activity tasks that will be queued on tasklist which will be then be assigned to workers. API support for creation and deletion of activity and workflow types gives great flexibility. Inspired by the simplicity of the approach, In this project, I have tried to clone subset of features provided by SWF. Developer Guide and API Reference is great place to know more (http://aws.amazon.com/documentation/swf/)

Supported Actions

• RegisterWorkFlowType
• RegisterActivityType
• StartWorkflowExecution
• TerminateWorkflowExecution
• RequestCacnelWorkflowExecution
• PollForDecisionTask
• RespondDecisionTaskCompleted
• PollForActivityTask
• RespondActivityTaskCompleted

Timeouts

Timeouts for Workflow Execution, Decision Task Start to Close, Activity Task SchedToClose, SchedToStart, StartToClose are completely "honored"

Starting workflowsvc

Before starting the service, a redis server and mongodb has to be started. Start the workflow service, workflowsvc.py,

Sample clients

client/simpleclient.py: This client will cover complete the life cycle of a workflow execution by registering workflow, activity types and starting a workflow execution for which a decider will create a task that will be completed by a worker. Finally, the decider will mark the execution as completed

client/timeoutclient.py: This client will run workflow executions that tests different timeouts honored by the workflowsvc

client/terminateclient.py: This client covers terminating workflow execution abruptly

TODO

• Visibility Actions
• Child Workflow
• Timers
• Domains
• Task Cancellation
• Markers, Tags
• Signals
• Versioning