WORKFLOW SERVICE USING STATE TRANSFER

摘要

A provider network for providing continuous workflow service for an open-ended number of workflows using non-persistent threads. In some cases, the provider network includes a workflow handling service and a workflow evaluation service. The workflow handling service may receive indications of task completion events related to respective workflows, and in turn may send non-blocking requests for workflow decisions from the workflow evaluation service. In generating a workflow decision, the workflow evaluation service may determine resources for executing a workflow evaluation thread for generating the workflow decision. Further, a given workflow evaluation thread may determine a workflow decision without relying on a previously stored state for a state machine corresponding to the workflow. In this way, a given workflow decision may be determined on different allocated resources at different points in time in maintaining the workflow.

主权项

1. A system, comprising:
a workflow data store configured to store workflow definitions registered with the workflow service by respective clients, wherein respective workflow definitions define states of a respective workflow indicating tasks to be performed for the respective workflow and transitions between the states; a workflow handling service implemented by one or more computing devices and configured to:
maintain workflow logs for respective workflows; andrequest a workflow decision for a particular workflow of the respective workflows to determine a task to schedule for the respective workflow; and a workflow evaluation service implemented by one or more computing devices and configured to:
receive a request for the workflow decision for the particular workflow, wherein the request includes a workflow log for the particular workflow;generate a state machine for the particular workflow according to a particular workflow definition for the particular workflow;apply the workflow log for the particular workflow to the state machine to transition the state machine to a current state for the particular workflow;evaluate the current state for the particular workflow to determine the workflow decision for the particular workflow; andsend the workflow decision for the particular workflow to the workflow handling service; wherein the workflow handling service is further configured to:
receive the workflow decision from the workflow evaluation service;log the workflow decision in the workflow log for the particular workflow; andschedule for execution a task corresponding to the workflow decision.