1. A computer-implemented system for facilitating communication between a plurality of building automation subsystems and a plurality of applications, comprising: a first database storing an ontological model of a building automation system (BAS), wherein the ontological model represents hierarchical relationships between BAS object types without storing data values for particular instances of BAS objects; a second database storing information for the plurality of building automation subsystems, wherein the second database comprises at least one record for each of a plurality of BAS objects, wherein the second database stores each record with a projected semantic type string comprising multiple levels of hierarchical type information for each BAS object and based on the ontological model stored in the first database; and a messaging engine configured to receive a message from one of the disparate building automation subsystems and for one of the plurality of applications, wherein the messaging engine is configured to use the information in the second database to transform the message into a standard format, to append the projected semantic type string to the transformed message, and to provide the transformed and appended message, including the projected semantic type string, to one of the plurality of applications.