1. A computer implemented method comprising: using a computing system having at least one processor to perform a process, the process comprising: receiving a graph of nodes and edges where the nodes represent locations and the edges represent travel between locations, wherein the edges are annotated with edge constraints describing parameters regarding travel between locations; receiving a set of orders; converting the set of orders into a set of graph items in a format suitable for processing by a mapping engine, the graph items including at least a source node and destination node, the graph items having one or more order constraints comprising a first type of constraints that are inherent in data corresponding to the set of orders and a second type of constraints that are derived from the data corresponding to the set of orders, the first type of constraints comprising at least one of, a time constraint, a consolidation constraint, and a packing constraint; mapping the graph items onto one or more transportation legs using the mapping engine, the one or more transportation legs comprising a plurality of locations represented by nodes and one or more edges, the graph items mapped to the one or more transportations legs satisfy the edge constraints for the one or more transportation legs and the order constraints for the graph items comprising inherent constraints and derived constraints; generating a set of candidate paths between respective source nodes and respective destination nodes for at least a subset of the set of graph items, wherein the generation of any one of the candidate paths of the set of candidate paths is made subject to honoring respective order constraints comprising inherent constraints, derived constraints, leg constraints, and constraints for combinations of candidate paths and subsets of the subset of the set of graph items; and assigning at least some orders of the set of orders to a selected one of the candidate paths using the graph items and the graph of nodes and edges of the selected one of the candidate paths.