The problem of service routing (or dynamic service composition) has recently emerged as a consequence of the distributed composable services model residing in middleware layer(s). However, existing solutions are mostly suitable for small- or medium-scale service overlay networks, as service routing is performed over flat overlay topologies such as a mesh. Due to their increasing routing information maintenance costs, these flat (single-level) topology solutions cannot cope with large-scale service overlay networking. For better scalability, in this paper, we provide a hierarchical service routing framework, which comprises three parts. In the first part, we organize the overlay network nodes into clusters based on their Internet distances. We then construct a hierarchically fully connected (HFC) topology based on the clustering result. In such a topology, nodes within a cluster are considered fully connected, and the clusters themselves are also fully connected by their border nodes. In the second part, a hierarchical state information distribution protocol will be provided so that each node in the system maintains full state of the nodes in its own cluster and aggregate state of other clusters in the system. In the third part, we present how service paths can be computed hierarchically in a divide-and-conquer fashion. Through simulation tests, we demonstrate that while achieving much better scalability, our framework provides also as good and efficient service paths as single-level mesh solutions.
['Jingwen Jin', 'Klara Nahrstedt']
Large-scale service overlay networking with distance-based clustering