List of applications
Maybe we should also write about different types of applications, their purposes and types of users.
(We probably should distinguish different levels of SDDI integration for the applications. Maybe 3 LOIs are appropriate or sufficient. LOI 1 means that the application is just registered within the catalog service, but no further SDDI components are being involved. LOI 2 means everything from LOI 1 and that the application makes use of at least one SDDI service (or one conceptual data model and/or encoding?). LOI 3 could mean that all application data is coming from SDDI services. But it could also mean that all application data sources again are registered in the SDDI catalog. How do we incorporate security aspects, i.e. how should we express, if applications support authentication, authorization, and access control (AAA)? We need to check if there are already publications on some classification of "levels of integration" within SDIs.)
(Level of Integration could also relate to the question whether datasets are just visually integrated or they are semantically integrated)
(We should also consider "Levels of Security" or something similar)