orchardcore-workflow-activity

Create a class inheriting TaskActivity<T> for actions or EventActivity for triggers, override DisplayText, Category, GetPossibleOutcomes, and ExecuteAsync. Then add an ActivityDisplayDriver, three Razor shape templates, and register with services.AddActivity in Startup.

A Task performs work and returns outcomes immediately, and cannot start a workflow. An Event halts the workflow via Halt(), waits for an external trigger, gates on CanExecuteAsync, and resumes through Resume, and it can serve as a workflow start point.

Use the GetProperty and SetProperty helpers from the Activity base class, which store values as JSON in the activity's Properties bag keyed by member name. Provide a default factory so unset properties do not return null, and the state survives halt and resume.

Yes, declare user-editable fields as WorkflowExpression<T> and evaluate them at runtime with IWorkflowExpressionEvaluator for Liquid or IWorkflowScriptEvaluator for JavaScript. The view model typically exposes the raw expression string for the editor.

Events must override Name to a stable value because external code references the event by name to resume it. Also verify CanExecuteAsync returns true for the triggering input and that outcome names in Resume match those declared in GetPossibleOutcomes.