The image shows a diagram of third-party interactions. There are three BPEL processes: BPEL Process A, the Buyer; BPEL Process B, the Seller; and BPEL Process C, the Shipper. Each has an invoke activity and a receive activity. The following actions take place:

1. BPEL Process A uses its invoke activity to send a request to BPEL Process B, by way of a WSDL partner link.

2. BPEL Process B's receive activity receives this request, and has its invoke activity send a request to BPEL Process C, by way of a WSDL partner link.

3. BPEL Process C's receive activity receives B's request, processes it, and then sends a response to BPEL Process A using its own invoke activity.

4. BPEL Process A's receive activity receives the response from C (by way of the WSDL partner link).