Service-oriented architectures evolved rapidly as the solution to the latest requirements for loosely-coupled distributed computing. Into this broad context several approaches emerged towards the discovery and the systematic composition/orchestration of services. One of the next challenges in this field is the maintenance of service-oriented architectures towards accomplishing the ultimate goal of constructing eternal service-oriented systems out of loosely- coupled basic engineering elements. The particular problem we deal with in this paper is the dynamic maintenance of service orchestrations in the presence of unavailable services. Specifically, we focus on the dynamic substitution of stateful services that become unavailable during the execution of service orchestrations. As an answer to this problem, we propose the SIROCO middleware platform which is further detailed along with an experimental evaluation of our first prototype. Our findings show that SIROCO provides the necessary means for achieving dynamic maintenance with a reasonable expense on the execution of service orchestrations.