UML 101

The diagram in this page shows the entities (classes in UML) that make up a SiteGlow website, as well as the ways in which the entities are associated. The diagram in fairly self-explanatory, but you should be the following in mind:

• The boxes represent classes.
• The lines connecting the boxes represent associations between classes.
• The arrows in the lines represent the navigability of the association. For example, while the Domain and Site objects are associated, the association can only be navigate from the Site to the Domain, and not the other way around. In object-oriented code this means that writting Site.Domain would work, but writting Domain.Site would not.
• The labels next to the arrow heads represent the property name that must be used to access the associated object or object collection. If the arrow heads have no labels then the associated class is accessed via its own name. For example, to access a Publication from a Unit, write Unit.Publication, but to access a Unit from a Publication write Publication.Units.
  
• The asterisk beside the arrow heads represent multiplicity of the association. In this case, it means the association is not to a single class object, but rather to a collection of objects. For examle, every Unit object is associated to a single Publication, and every Publication is associated to a collection of Unit objects. In object-oriented code this would be written as Unit.Publication and Publication.Units[x] respectively, where x is the index or key to the collection (more about this later).