Use cases, cont'd
- Conversation exchange in a procurement process: B requests
price quotation; S gives quote; B places purchase order; S accept; 
S offers delivery dates; B accepts; B acks delivery; S acks;
B pays; S sends receipt.
- Bank A buys Bank B.  Bank A has always used SAP for internal
processes; Bank B uses IBM dbms running PeopleSoft software.
You work for the IT department; you now have three weeks to
provide access to the customer records of Bank B to the Bank A
systems.  Oh, and your colleagues in Bank B don't trust you yet.
- Amalgamated Interkludge runs a Huge Mainframe Application
which handles queries submitted through a proprietary message
queueing system.  Your job: provide Web access to the HMA.