1. A method for representing and accessing related application data that is stored in memory of a server and is arranged in hierarchical relationships, the method being executed by the server and comprising: providing classes including: a hierarchy base class providing at least one hierarchical functionality related to the hierarchical relationships; at least one hierarchy subclass that is derived from the hierarchy base class; and at least one application class for the application data, wherein the at least one application class defines at least one of attributes and methods in a transportation optimization context; instantiating objects including: a first application object of the at least one application class; a second application object of the at least one application class, wherein the second application object is different from the first application object; a first hierarchy object of the at least one hierarchy subclass; and a second hierarchy object of the at least one hierarchy subclass, wherein the second hierarchy object is different from the first hierarchy object; linking, by using a processor of the server, the first application object to the first hierarchy object, and the second application object to the second hierarchy object; providing a first reference to the first hierarchy object for use by the at least one hierarchical functionality, the first reference referencing the second hierarchy object; providing a second reference to the second hierarchy object for use by the at least one hierarchical functionality, the second reference referencing the first hierarchy object; and relating the first application object and the second application object by using the first hierarchy object and the second hierarchy object, wherein the first application object accesses application data stored in the second application object by implementing the at least one hierarchical functionality using the first reference to link the first hierarchy object to the second hierarchy object to access the second application object via the second hierarchy object, and wherein the second application object accesses application data stored in the first application object by implementing the at least one hierarchical functionality using the second reference to link the second hierarchy object to the first hierarchy object to access the first application object via the first hierarchy object.