1. A computer-implemented method of providing a canonical hierarchical schema (CHS) based on a plurality of source hierarchical schemas, the method being executed using one or more processors and comprising: receiving the plurality of source hierarchical schemas, each source hierarchical schema being stored as a computer-readable document in computer-readable memory; processing, using the one or more processors, the source hierarchical schemas to generate a merged graph, the merged graph comprising a plurality of merged nodes, each merged node being provided based on one or more nodes from at least two of the source hierarchical schemas; determining, using the one or more processors, that the merged graph includes one or more conflicts and, in response, resolving each conflict of the one or more conflicts to generate a conflict-free merged graph, wherein resolving comprises splitting one or more merged nodes into respective sub-sets of merged nodes; defining a constraints satisfaction problem (CSP) that includes a plurality of constraints associated therewith based on the conflict-free merged graph; processing, using the one or more processors, the CSP to generate a plurality of mediated hierarchical schemas (MHSs), each MHS being a solution to the CSP; identifying an MHS of the plurality of MHSs as an optimum MHS, wherein the CHS is provided as the optimum MHS; and storing the CHS as a computer-readable document in the computer-readable memory.
2. The method of claim 1 , further comprising receiving a plurality of field mappings and a plurality of semantic correspondences, each field mapping and semantic correspondence being associated with a set of source hierarchical schemas, wherein the merged graph is generated based on the plurality of field mappings and the plurality of semantic correspondences.