Introduction to TRANSFER Delivery System

The Way Depots Work The TRANSFER Environment
2-12 109426—Introduction to TRANSFER Delivery System
The Way Depots Work
Although TRANSFER correspondents care only about the external representation of the
data in their depots, programmers and system managers who are concerned with the size
of their database need to understand the internal structure of a depot. What does it really
mean for a profile or folder to be in a depot or for a package to be in a folder?
A depot is not a single file. TRANSFER assigns unique IDs to depots, folders, and
items. The depot ID appears in records of various kinds, distributed over several files in
the TRANSFER database. The depot ID in profile and folder records shows that the
profile and folder are in that depot. The item ID appears in folder records and shows
that the item is in that folder.
Figure 2-4 illustrates the relationship of depots, folders, items, and packages in the
TRANSFER database. TRANSFER uses disk storage space efficiently by having no
duplication of data at a node. As the figure shows, items are stored only once in the
database, no matter how they are linked. The same item can be a component of several
packages; it can be stored in a folder and also be a component of a package; or it can be
in several folders, and the folders can be in different depots. Still, the item is kept only
once in the TRANSFER database.