Abstract—Service composition schemes create high-level application services by combining several basic services. Service composition schemes for dynamic, open systems, such as those found in pervasive environments, must be cognizant of the possibility of failures and attacks. In open systems, it is seldom feasible to guarantee the reliability of each node prior to access; however, there may be several possible ways to compose the same high-level service, each having a different (though possibly overlapping) set of nodes that can satisfy the composition. We approach this problem with a Reliable Service Composition middleware component, ReSCo, to determine trustworthy compositions and nodes for service composition in dynamic, open systems. ReSCo is a modular, adaptive middleware component that selects from possible composition paths and nodes to enhance reliability of service compositions. ReSCo can work with a broad range of both service composition algorithms and trust establishment ...