Here we explain the composition activities
This activity lets you complete a workflow and lets you specify an outcome.
Set Workflow Output
If using a workflow as a subworkflow you can use this activity to set an output variable on the workflow.
Thit activity lets you dispatch an other workflow from this workflow which will create its own workflow instance. You can select a workflow, send correlation data, specify input and if you want to wait for the dispatched workflow to finish. Under the output tab you can map the output of the dispatched workflow to a variable in the main workflow.