Needs

The view will be broken up into components. A single component encomposes those data elements and arcs that are added by a single Import statement by the user. This might just be an implementation issue, eg: the user may or may not be aware of the existence of components.

We are given a graph corresponding to a database. In order to construct a view based on this graph what do we need to do?

1. Extract a node without its parent
2. Extract a node that includes only those children that are specified
3. Add virtual nodes and virtual edges

Given the above, a component will need to do one or more of the following basic operations:

1. Describe a path down to an object which will be in the view.
2. List those children - if any - of each object specified above who will also be in the view.
3. Denote some virtual name associated with all parentless objects that is within the current component.
4. Specify in some way the creation of new nodes and edges.

I am not convinced that we need to implicitly add all edges between objects Imported with all previous components of a view. It doesn't seem like we lose anything by not doing this and it will make the implementation easier and faster.