  The problem of identifying the k-shortest paths KSPs for short in a dynamic
road network is essential to many location-based services. Road networks are
dynamic in the sense that the weights of the edges in the corresponding graph
constantly change over time, representing evolving traffic conditions. Very
often such services have to process numerous KSP queries over large road
networks at the same time, thus there is a pressing need to identify
distributed solutions for this problem. However, most existing approaches are
designed to identify KSPs on a static graph in a sequential manner, restricting
their scalability and applicability in a distributed setting. We therefore
propose KSP-DG, a distributed algorithm for identifying k-shortest paths in a
dynamic graph. It is based on partitioning the entire graph into smaller
subgraphs, and reduces the problem of determining KSPs into the computation of
partial KSPs in relevant subgraphs, which can execute in parallel on a cluster
of servers. A distributed two-level index called DTLP is developed to
facilitate the efficient identification of relevant subgraphs. A salient
feature of DTLP is that it indexes a set of virtual paths that are insensitive
to varying traffic conditions in an efficient and compact fashion, leading to
very low maintenance cost in dynamic road networks. This is the first treatment
of the problem of processing KSP queries over dynamic road networks. Extensive
experiments conducted on real road networks confirm the superiority of our
proposal over baseline methods.
