19. The integration server system of claim 18 wherein, in response to a request for creation of one or more new data objects from a client application, the application programming interface coordinates a response to the request including creating an instance of the data object in the database schema and returning a reference to the data object instance to the requesting client application thereby allowing the integration server to change database schemas without changing the model application programming interface.
19. The integration server system of claim 18 wherein, in response to a request for creation of one or more new data objects from a client application, the application programming interface coordinates a response to the request including creating an instance of the data object in the database schema and returning a reference to the data object instance to the requesting client application thereby allowing the integration server to change database schemas without changing the model application programming interface. 20. The integration server system of claim 19 wherein data objects can be associated with one or more other data objects in the model description and wherein the associations between data objects are stored in the database, each association being an attribute of a data object represented by a column of a table in the database schema and wherein each instance of a data object is assigned an ID number in the database table, wherein the ID number of a first instance of a database object is stored in an association column of a second instance of a data object to define an association between two data objects.