Lost/Found Element Creation

In this section, you will learn the concept of lost/fountd element and see how to create lost/found element from the sequence diagram graphical interface.
This section includes the following contents:

1. Concept
   
2. Create lost/found element
   

1. Concept

• A found message is a message where the receiving event occurrence is known, but there is no (known) sending event occurrence. We interpret this to be because the origin of the message is outside the scope of the description. This may for example be noise or other activity that we do not want to describe in detail. The semantics is simply the trace (receiveEvent)
  
• A lost message is a message where the sending event occurrence is known, but there is no receiving event occurrence. We interpret this to be because the message never reached its destination. The semantics is simply the trace (sendEvent).
  

2. Create lost/found element

To create a lost/found element directly in your sequence diagram, click the icon in toolbar items.

Drag and drop the icon in the sequence diagram, it will appears a lost/found element

Then, a message creation dialog appears, select the operation/method name in Operation field and click the OK button

A found element has been created now

Also, you create a lost/found element on the other side of the object and connect the object to the second lost/found element

Then, a message creation dialog appears, you can select "Return" or "Throw exception" in Operation field

The Found element and Lost element have been created now