我应该使用子工作流还是使用活动来启动新工作流

Question

Like the title. Seems like both ways should work but child workflow seems easier.

Answer 1

It's strongly recommended to always use activity to start new workflow and never use ChildWorkflow until the reset feature is working with Child Workflow https://github.com/uber/cadence/issues/3914

https://github.com/temporalio/temporal/issues/3141

To get result back to parent from child workflow, use signal. To link the two workflows, use search attributes when starting new workflows.

Answer 2

As Quanzheng said, if you need to use Reset, then Child Workflows are not currently an option.

Apart from that issue, the semantics of Child Workflows are quite different from starting a new workflow via an Activity.

The primary differences are that:

1. By default, Terminations and Cancellations are propagated to Child Workflows, although this can be overridden at Child Workflow creation time. This behavior is possible to implement with co-equal Workflows, but requires a careful Workflow implementation which never terminates without terminating its children.
2. Waiting for a Child Workflow to complete is directly supported in the Temporal API, whereas waiting for an arbitrary Workflow is not. See this issue .

Whether you need either of those capabilities, and whether you use Reset, should tell you if Child Workflows are appropriate to your use-case.