In Virtual DataPort Administration tool, an association represents a relationship between two views in a similar way a join view links one view with another one. It can be created either on the base view or derived view using the two endpoints and list of mapping.
On the other hand, it is also possible to traverse the association of a view at runtime using the RESTful Web service. An association can only be traversed if the view has a primary key defined in it.
For more information, you can have a look at the section [Creating an Association](https://community.denodo.com/docs/html/browse/6.0/vdp/administration/restful_architecture/associations/creating_an_association) of Virtual DataPort Administration Guide and the Knowledge Base article [Association in Denodo](https://community.denodo.com/kb/view/document/Associations%20in%20Denodo?category=Combining+Data).
Hope this helps!!