13. A data source modeling system for heterogeneous data sources, the data source modeling system comprising: a processor; and a memory coupled to the processor and comprising computer readable program code embodied in the memory and when executed by the processor causes the processor to perform operations comprising: defining a first interface for a first abstract sub-model of a first sub-model without defining a data source structure for the first sub-model responsive to user input through a user interface; defining a second interface for a second abstract sub-model of a second sub-model without defining a data source structure for the second sub-model responsive to user input through the user interface; defining a connection between the first interface of the first abstract sub-model and the second interface of the second abstract sub-model; defining a first data source structure for the first sub-model separately from the first abstract sub-model, wherein the first data source structure defines a coupling to the first interface of the first abstract sub-model; defining a second data source structure for the second sub-model separately from the second abstract sub-model, wherein the second data source structure defines a coupling to the second interface, wherein the first and second data source structures are heterogeneous data source structures having respective different data source structure types, and wherein at least one of the first and second data source structure types comprises a database structure; after defining the first and second data source structures for the first and second sub-models, generating a unified data source model including the first and second sub-models having the respective first and second data source structures and having the respective first and second interfaces of the first and second abstract sub-models, wherein the first and second sub-models are coupled through the connection defined between the respective first and second interfaces of the first and second abstract sub-models; and rendering the unified model including the first and second sub-models having the respective first and second data source structures and coupled through the connection between the first and second interfaces on a display.
13. A data source modeling system for heterogeneous data sources, the data source modeling system comprising: a processor; and a memory coupled to the processor and comprising computer readable program code embodied in the memory and when executed by the processor causes the processor to perform operations comprising: defining a first interface for a first abstract sub-model of a first sub-model without defining a data source structure for the first sub-model responsive to user input through a user interface; defining a second interface for a second abstract sub-model of a second sub-model without defining a data source structure for the second sub-model responsive to user input through the user interface; defining a connection between the first interface of the first abstract sub-model and the second interface of the second abstract sub-model; defining a first data source structure for the first sub-model separately from the first abstract sub-model, wherein the first data source structure defines a coupling to the first interface of the first abstract sub-model; defining a second data source structure for the second sub-model separately from the second abstract sub-model, wherein the second data source structure defines a coupling to the second interface, wherein the first and second data source structures are heterogeneous data source structures having respective different data source structure types, and wherein at least one of the first and second data source structure types comprises a database structure; after defining the first and second data source structures for the first and second sub-models, generating a unified data source model including the first and second sub-models having the respective first and second data source structures and having the respective first and second interfaces of the first and second abstract sub-models, wherein the first and second sub-models are coupled through the connection defined between the respective first and second interfaces of the first and second abstract sub-models; and rendering the unified model including the first and second sub-models having the respective first and second data source structures and coupled through the connection between the first and second interfaces on a display. 14. The data source modeling system of claim 13 wherein the first data source structure type of the first data source structure comprises a database structure, and wherein the second data source structure type of the second data source structure comprises non-database file structure.