George Spanoudakis Khaled Mahbub Requirements Monitoring for Service-Based Systems: Towards a framework based on Event Calculus. 379-384 2004 conf/kbse/2004 ASE http://csdl.computer.org/comp/proceedings/ase/2004/2131/00/21310379abs.htm db/conf/kbse/ase2004.html#SpanoudakisM04