TaskFlow/Best practices

Summary

Why

Since taskflow creates a path toward stable, resumable, and trackable workflows it is helpful to have a small set of recommended best practices to make sure you as a user of taskflow (the library) maximize the benefit you receive from using taskflow. Certain common patterns and best practices will be listed below to show the what, why and how so that you can maximize your taskflow experience and minimize the pain associated with understanding some of the taskflow key primitives.

Note: this list will likely continue growing as new usages of taskflow emerge (and new features are introduced into taskflow), please feel free to add any of your own below.

Top 10

Create reuseable tasks that do one thing well; if that task has side-effects undo those side-effects in the revert method.
Clearly define what a task provides so that future (potentially not yet created) tasks can depend on those outputs.
Clearly define what a task requires so that engine/s can deduce the correct order to run your tasks in.
Link tasks that do one thing well together with the supplied patterns to create flows that do many things well together.
Be very careful about RPC boundaries (especially when the workflow spans this boundary) and choose how you deal with this in a thought out manner.
Always associate a (major, minor) version with your tasks so that on software upgrades the previously (potentially partially) completed tasks can be migrated & resumed/reverted.
Return serializable objects from tasks not resources (or other non-serializable objects); expect that all returned objects may be persisted indefinitely.
Clearly name your tasks with relevant names; names are how restarted flows are re-associated with there previously (potentially partially) completed tasks for resumption or reversion so choose carefully.
Raise meaningful exceptions to trigger task and flow reversion; the exception which triggered the flow reversion will be persistently stored (and can be referred to later), make sure it is as useful & meaningful as possible.
Associate accessible (not instance/module private) creation functions with a flow so that the surrounding application does not need to be as involved in the flow & task resumption process.