1. A method for storing communication messages in a relational database, comprising: accepting an object model comprising data elements and associations between the data elements, derived from a hierarchically-structured HL7 specification; defining a relational database that represents the object model based on the data elements and the associations; receiving a communication message comprising data items corresponding to one or more of the data elements, the message conforming to the HL7 specification; and storing the data items in the relational database so as to preserve the associations between the data items, as defined in the object model.