Abstract System ar hite tures that ross organisational boundaries are usually implemented based on Web servi e te hnologies due to their inher-

ent interoperability benets. With in reasing exibility requirements, su h

as on-demand servi e provision, a dynami approa h to servi e ar hite ture

fo ussing on omposition at runtime is needed. The possibility of te hni al

faults, but also violations of fun tional and semanti onstraints require a

omprehensive notion of ontext that aptures omposition-relevant aspe ts.

Context-aware te hniques are onsequently required to support onstraint val-

idation for dynami servi e omposition. We present te hniques to respond to

problems o urring during the exe ution of dynami ally omposed Web ser-

vi es implemented in WS-BPEL. A notion of ontext overing physi al and

ontra tual faults and violationsis used to safeguard omposed servi e exe-

utions dynami ally. Our aim is to present an ar hite tural framework from

an appli ation-oriented perspe tive, addressing pra ti al onsiderations of a

te hni al framework.