1. A computer-implemented method 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 a computer, 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 computer, that the merged graph includes one or more conflicts and, in response, resolving each conflict of the one or more conflicts to generate a computed -transitive-edge-free, conflict-free merged graph as a unified data model (UDM), wherein resolving comprises splitting one or more merged nodes into respective sub-sets of merged nodes; generating a canonical data model (CDM) by applying a relevance rating to the nodes of the UDM based on a received context in a user request, wherein the generated CDM is an excerpt from the UDM with nodes containing at least one value consistent with the received context, and wherein the CDM is used as a bridge language with consistent and semantically unambiguous meaning of data structures and data elements used by two or more interfacing software applications executing on different computing systems; and continuously maintaining the CDM based on guides and mappings received from one or more external data stores.