This example illustrates a formal verification of service interactions.  The service communication models either a synchronous "invoke only", synchronous "invoke-reply" or an asychronous "invoke-receive" interaction.

To perform the verification:

1  In LTSA WS-Engineer switch to the Interactions tab 
2. Select both the buyer.bpel and buyer.wsdl files and drag-and-drop on to the "Processes and Interfaces" listbox on the tab page.
2. Select both the marketplace.bpel and marketplace.wsdl files and drag-and-drop on to the "Processes and Interfaces" listbox on the tab page.
4. Click Verify and note that a violation occurs at the marketplace_buyer_reply_requireproduct expected action.

The violation occurs because of an incomplete invocation sequence, where the buyer process invokes the marketplace operation "requireProduct" and does not eventually follow with a reply action for the operation.

Test 2 provides a solution to this violation.
 
