Object lifecycle — create, found, lost, destroy
The four UML interaction lifecycle markers in one short diagram — a create message draws its arrow to the new participant's box, a found message starts from a filled circle, a lost message ends at one, and destroy terminates a lifeline with an ✕.
For the software engineer
UML interactions model not just messages but the birth and death of participants — the part most text-to-diagram tools skip. This tiny diagram shows all four markers.
Create. Factory -> *Worker — the * prefix creates Worker; its arrow lands on the side of the new participant's box, which appears partway down rather than at the top, the UML convention for "instantiated here."
Found and lost. o-> Worker is a found message — it starts from a filled circle, meaning "from outside the modelled scope" (an external trigger). Worker -x is a lost message — it ends at a circle, a fire-and-forget whose receiver isn't shown.
Destroy. destroy Worker terminates the lifeline with the ✕ marker, so the diagram shows exactly when the object ceases to exist.