Fedora Repository Views

...

But the angle one views the repository might also affect the number of entries seen. The above, recursive approach will always lead to one entry per data object. The remedy for this is to mark some classes as Entries for a certain view angle. This means that to compute the records for a given view angle, the view of all objects of a class that is an Entry should be computed. This is the view of the repository.

Fedora Implementation 

This section describes how the above could be implemented in Fedora. 

...

We want to be able to return all Views in a given Collection for a given State that have been modified after a given Time. To do this, we maintain a database of Views that is updated on all changes of an object.

Maintaining state

Whenever one of the components of a View is changed, the whole View counts as updated. As such, any services that subscribe to the View in any way need to be notified. If there is a search index for the Views, and one is updated, its state in the index must be recomputed.

The problem arrives when trying to do this. The View system is designed to ease the computing of a View when knowing the Entry object. The reverse is finding the Views, ie. the Entry objects, that have this data object in their View. Rather than encoding this information in the model, we chose to keep an external record of all the views.

...